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Identifying colorectal cancer patient populations responsive to chemotherapy or chemoradiation therapy before surgery remains a challenge. Recently validated mouse protocols for organoid irradiation employ the single hit multi-target (SHMT) algorithm, which yields a single value, the D0, as a measure of inherent tissue radiosensitivity. Here, we translate these protocols to human tissue to evaluate radioresponsiveness of patient-derived organoids (PDO) generated from normal human intestines and rectal tumors of patients undergoing neoadjuvant therapy. While PDOs from adenomas with a logarithmically expanded Lgr5+ intestinal stem cell population retain the radioresistant phenotype of normal colorectal PDOs, malignant transformation yields PDOs from a large patient subpopulation displaying marked radiosensitivity due to reduced homologous recombination–mediated DNA repair. A proof-of-principle pilot clinical trial demonstrated that rectal cancer patient responses to neoadjuvant chemoradiation, including complete response, correlate closely with their PDO D0 values. Overall, upon transformation to colorectal adenocarcinoma, broad radiation sensitivity occurs in a large subset of patients that can be identified using SHMT analysis of PDO radiation responses. Significance: Analysis of inherent tissue radiosensitivity of patient-derived organoids may provide a readout predictive of neoadjuvant therapy response to radiation in rectal cancer, potentially allowing pretreatment stratification of patients likely to benefit from this approach.

The present study explores PSA density (PSA-D) as predictor of biochemical and local failure in organ-confined prostate cancer at 3-6 months after hypofractionated stereotactic ablative radiotherapy (SABR).A cohort of 219, hormone-naïve, NCCN intermediate-risk prostate cancer patients were derived from a phase 2 study of 5 × 9 Gy prostate cancer SABR. PSA-D was calculated at 3 and 6 months by dividing serum PSA by the MR-derived prostate CTV, while the slope of the 3-6 months curve was used to express the kinetics of PSA-D decay.The median follow-up was 60.3 (range 46-76) months, and the actuarial 7-year bRFS was 98.0% for intermediate-risk favorable (FIR) patients versus 84.5% for the unfavorable (UIR) subgroup (P = 0.02). Fourteen patients developed a Phoenix-defined biochemical PSA relapse (bRFS) at a median of 34.2 months, 11 confirmed withEarly post-treatment PSA-D kinetics transcends pre-treatment risk stratification of tumor relapse and adds a nuance in the biological characterization of intermediate-risk prostate cancer phenotypes. The dual adverse PSA-D algorithm may serve as a tool to validate current search of classifiers of radioresistance in prostate cancer with therapeutic implications.

PURPOSE: Although 24 Gy single-dose radiation therapy (SDRT) renders >90% 5-year local relapse-free survival in human solid tumor lesions, SDRT delivery is not feasible in ~50% of oligometastatic lesions owing to interference by dose/volume constraints of a serial organ at risk (OAR). Conformal OAR avoidance is based on a hypothetical model positing that the recently described SDRT biology specifically permits volumetric subdivision of the SDRT dose, such that high-intensity vascular drivers of SDRT lethality, generated within a major tumor subvolume exposed to a high 24 Gy dose (high-dose planning target volume [PTV(HD])), would equilibrate SDRT signaling intensity throughout the tumor interstitial space, rendering bystander radiosensitization of a minor subvolume (perfusion-modulated dose sculpting PTV [PTV(PMDS)]), dose-sculpted to meet a serial OAR dose/volume constraint. An engineered PTV(PMDS) may thus yield tumor ablation despite PMDS dose reduction and conformally avoiding OAR exposure to a toxic dose. METHODS AND MATERIALS: Dose fall-off within the PTV(PMDS) penumbra of oligometastatic lesions was planned and delivered by intensity modulated inverse dose painting. SDRT- and SDRT-PMDS–treated lesions were followed with periodic positron emission tomography/computed tomography imaging to assess local tumor control. RESULTS: Cumulative baseline 5-year local relapse rates of oligometastases treated with 24 Gy SDRT alone (8% relapses, n = 292) were similar in moderate PTV(PMDS) dose-sculpted (23-18 Gy, n = 76, 11% relapses, P = .36) and extreme dose-sculpted (

Background/Aims: It is unknown whether cancer stem cells respond differentially to treatment compared with progeny, potentially providing therapeutic vulnerabilities. Our program pioneered use of ultra-high single dose radiotherapy, which cures diverse metastatic diseases at a higher rate (90-95%) than conventional fractionation (~65%). Single dose radiotherapy engages a distinct biology involving microvascular acid sphingomyelinase/ceramide signaling, which, via NADPH oxidase-2-dependent perfusion defects, initiates an adaptive tumor SUMO Stress Response that globally-inactivates homologous recombination repair of double stand breaks, conferring cure. Accumulating data show diverse stem cells display heightened-dependence on homologous recombination repair to repair resolve double stand breaks. Methods: Here we use colorectal cancer patient-derived xenografts containing logarithmically-increased Lgr5+ stem cells to explore whether optimizing engagement of this acid sphingomyelinase dependent biology enhances stem cell dependent tumor cure. Results: We show radioresistant colorectal cancer patient-derived xenograft CLR27-2 contains radioresistant microvasculature and stem cells, whereas radiosensitive colorectal cancer patient-derived xenograft CLR1-1 contains radiosensitive microvasculature and stem cells. Pharmacologic or gene therapy enhancement of single dose radiotherapy-induced acid sphingomyelinase/ceramide-mediated microvascular dysfunction dramatically sensitizes CLR27-2 homologous recombination repair inactivation, converting Lgr5+ cells from the most resistant to most sensitive patient-derived xenograft population, yielding tumor cure. Conclusion: We posit homologous recombination repair represents a vulnerability determining colorectal cancer stem cell fate, approachable therapeutically using single dose radiotherapy.

Tissue survival responses to ionizing radiation are nonlinear with dose, rather yielding tissue-specific descending curves that impede straightforward analysis of biologic effects. Apoptotic cell death often occurs at low doses, while at clinically relevant intermediate doses, double-strand break misrepair yields mitotic death that determines outcome. As researchers frequently use a single low dose for experimentation, such strategies may inaccurately depict inherent tissue responses. Cutting edge radiobiology has adopted full dose survival profiling and devised mathematical algorithms to fit curves to observed data to generate highly reproducible numerical data that accurately define clinically relevant inherent radiosensitivities. Here, we established a protocol for irradiating organoids that delivers radiation profiles simulating the organ of origin. This technique yielded highly similar dose–survival curves of small and large intestinal crypts in vivo and their cognate organoids analyzed by the single-hit multi-target (SHMT) algorithm, outcomes reflecting the inherent radiation profile of their respective Lgr5+ stem cell populations. As this technological advance is quantitative, it will be useful for accurate evaluation of intestinal (patho)physiology and drug screening. Significance: These findings establish standards for irradiating organoids that deliver radiation profiles that phenocopy the organ of origin. See related commentary by Muschel et al., p. 927

Recent data establish a logarithmic expansion of leucine rich repeat containing G protein coupled receptor 5-positive (Lgr5+) colonic epithelial stem cells (CESCs) in human colorectal cancer (CRC). Complementary studies using the murine 2-stage azoxymethane-dextran sulfate sodium (AOM-DSS) colitis-associated tumor model indicate early acquisition of Wnt pathway mutations drives CESC expansion during adenoma progression. Here, subdivision of the AOM-DSS model into in vivo and in vitro stages revealed DSS induced physical separation of CESCs from stem cell niche cells and basal lamina, a source of Wnt signals, within hours, disabling the stem cell program. While AOM delivery in vivo under non-adenoma-forming conditions yielded phenotypically normal mucosa and organoids derived thereof, niche injury ex vivo by progressive DSS dose escalation facilitated outgrowth of Wnt-independent dysplastic organoids. These organoids contained 10-fold increased Lgr5+ CESCs with gain-of-function Wnt mutations orthologous to human CRC driver mutations. We posit CRC originates by niche injury-induced outgrowth of normally suppressed mutated stem cells, consistent with models of adaptive oncogenesis.

Purpose This prospective phase 3 randomized trial was designed to test whether ultra high single-dose radiation therapy (24 Gy SDRT) improves local control of oligometastatic lesions compared to a standard hypofractionated stereotactic body radiation therapy regimen (3 × 9 Gy SBRT). The secondary endpoint was to assess the associated toxicity and the impact of ablation on clinical patterns of metastatic progression. Methods and Materials Between November 2010 and September 2015, 117 patients with 154 oligometastatic lesions (≤5/patient) were randomized in a 1:1 ratio to receive 24 Gy SDRT or 3 × 9 Gy SBRT. Local control within the irradiated field and the state of metastatic spread were assessed by periodic whole-body positron emission tomography/computed tomography and/or magnetic resonance imaging. Median follow-up was 52 months. Results A total of 59 patients with 77 lesions were randomized to 24 Gy SDRT and 58 patients with 77 lesions to 3 × 9 Gy SBRT. The cumulative incidence of local recurrence for SDRT-treated lesions was 2.7% (95% confidence interval [CI], 0%-6.5%) and 5.8% (95% CI, 0.2%-11.5%) at years 2 and 3, respectively, compared with 9.1% (95% CI, 2.6%-15.6%) and 22% (95% CI, 11.9%-32.1%) for SBRT-treated lesions (P = .0048). The 2- and 3-year cumulative incidences of distant metastatic progression in the SDRT patients were 5.3% (95% CI, 0%-11.1%), compared with 10.7% (95% CI, 2.5%-18.8%) and 22.5% (95% CI, 11.1%-33.9%), respectively, for the SBRT patients (P = .010). No differences in toxicity were observed. Conclusions The study confirms SDRT as a superior ablative treatment, indicating that effective ablation of oligometastatic lesions is associated with significant mitigation of distant metastatic progression.

Primary organ-confined prostate cancer is curable with external-beam radiotherapy. However, prostate cancer expresses a unique radiobiological phenotype, and its ablation requires doses at the high-end range of clinical radiotherapy. At this dose level, normal tissue radiosensitivity restricts the application of curative treatment, and mandates the use of the most advanced high-precision treatment delivery techniques to spare critical organs at risk. The efficacy and tolerance of dose-escalated conventional fractionated radiotherapy and of the biological equivalent doses of moderate and extreme hypofractionation are reviewed. Current studies indicate that novel risk-adapted techniques to spare normal organs at risk are still required to deploy high-biological equivalent dose extreme hypofractionation, while affording preservation of quality of life and cost-effectiveness.

Tumor cure with conventional fractionated radiotherapy is 65%, dependent on tumor cell-autonomous gradual buildup of DNA double-strand break (DSB) misrepair. Here we report that single-dose radiotherapy (SDRT), a disruptive technique that ablates more than 90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase-mediated (ASMase-mediated) microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction after SDRT conferred an ischemic stress response within parenchymal tumor cells, with ROS triggering the evolutionarily conserved SUMO stress response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensable for homology-directed repair (HDR) of DSBs, HDR loss of function after SDRT yielded DSB unrepair, chromosomal aberrations, and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging after SDRT using peroxiredoxin-6 overexpression or the SOD mimetic tempol, prevented chromatin SUMO3 depletion, HDR loss of function, and SDRT tumor ablation. We also provide evidence of mouse-to-human translation of this biology in a randomized clinical trial, showing that 24 Gy SDRT, but not 3×9 Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing of SDRT/ASMase signaling, as current studies indicate that this pathway is tractable to pharmacologic intervention.

After 9/11, threat of nuclear attack on American urban centers prompted government agencies to develop medical radiation countermeasures to mitigate hematopoietic acute radiation syndrome (H-ARS) and higher-dose gastrointestinal acute radiation syndrome (GI-ARS) lethality. While repurposing leukemia drugs that enhance bone marrow repopulation successfully treats H-ARS in preclinical models, no mitigator potentially deliverable under mass casualty conditions preserves GI tract. Here, we report generation of an anti-ceramide 6B5 single-chain variable fragment (scFv) and show that s.c. 6B5 scFv delivery at 24 hours after a 90% lethal GI-ARS dose of 15 Gy mitigated mouse lethality, despite administration after DNA repair was complete. We defined an alternate target to DNA repair, an evolving pattern of ceramide-mediated endothelial apoptosis after radiation, which when disrupted by 6B5 scFv, initiates a durable program of tissue repair, permitting crypt, organ, and mouse survival. We posit that successful preclinical development will render anti-ceramide 6B5 scFv a candidate for inclusion in the Strategic National Stockpile for distribution after a radiation catastrophe.

Background and purpose To quantitate the accuracy, reproducibility and prostate motion mitigation efficacy rendered by a target immobilization method used in an intermediate-risk prostate cancer dose-escalated 5×9Gy SBRT study. Material and methods An air-inflated (150 cm3) endorectal balloon and Foley catheter with three electromagnetic beacon transponders (EBT) were used to mitigate and track intra-fractional target motion. A 2 mm margin was used for PTV expansion, reduced to 0 mm at the interface with critical OARs. EBT-detected ≥ 2 mm/5 s motions mandated treatment interruption and target realignment prior to completion of planned dose delivery. Geometrical uncertainties were measured with an in-house ESAPI script. Results Quantitative data were obtained in 886 sessions from 189 patients. Mean PTV dose was 45.8 ± 0.4 Gy (D95 = 40.5 ± 0.4 Gy). A mean of 3.7 ± 1.7 CBCTs were acquired to reach reference position. Mean treatment time was 19.5 ± 12 min, 14.1 ± 11 and 5.4 ± 5.9 min for preparation and treatment delivery, respectively. Target motion of 0, 1–2 and >2 mm/10 min were observed in 59%, 30% and 11% of sessions, respectively. Temporary beam-on hold occurred in 7.4% of sessions, while in 6% a new reference CBCT was required to correct deviations. Hence, all sessions were completed with application of the planned dose. Treatment preparation time > 15 min was significantly associated with the need of a second reference CBCT. Overall systematic and random geometrical errors were in the order of 1 mm. Conclusion The prostate immobilization technique explored here affords excellent accuracy and reproducibility, enabling normal tissue dose sculpting with tight PTV margins.

Background and purpose While favourable long-term outcomes have been reported in organ-confined prostate cancer treated with 5 × 7–8 Gy extreme hypofractionation, dose escalation to 5 × 9–10 Gy improved local control but was associated with unacceptable rates of late rectal and urinary toxicities. The purpose of this study was to explore the feasibility of intra-fractional prostate immobilization in reducing toxicity, to promote dose escalation with extreme hypofractionated radiotherapy in prostate cancer. Material and methods 207 patients received 5 consecutive fractions of 9 Gy. An air-inflated (150 cm3) endorectal balloon and an intraurethral Foley catheter with 3 beacon transponders were used to immobilize the prostate and monitor intra-fractional target motion. VMAT-IGRT with inverse dose-painting was employed in delivering the PTV dose and in sculpting exposure of normal organs at risk to fulfil dose-volume constraints. Results Introduction of air-filled balloon induced repeatable rectum/prostate complex migration from its resting position to a specific retropubic niche, affording the same 3D anatomical configuration daily. Intra-fractional target deviations ≤1 mm occurred in 95% of sessions, while target realignment in ≥2 mm deviations enabled treatment completion as scheduled. Nadir PSA at median 54 months follow-up was 0.19 ng/mL, and bRFS was 100%, 92.4% and 71.4% in low-, intermediate- and high-risk categories, respectively. Late Grade 2 GU and GI toxicities were 2.9% and 2.4%, respectively. No adverse changes in patient-reported quality of life scores were observed. Conclusion The unique spatial configuration of this prostate motion mitigation protocol enabled precise treatment planning and delivery that optimized outcomes of ultra-high 5 × 9 Gy hypofractionated radiotherapy of organ-confined prostate cancer.

We determined the prognostic importance of a positive posttreatment biopsy after prostate radiotherapy.A total of 382 patients underwent a posttreatment biopsy after external beam radiotherapy for clinically localized prostate cancer. Posttreatment biopsies were classified as positive (prostatic adenocarcinoma without typical radiation induced changes), negative (no evidence of carcinoma) or adenocarcinoma with a severe treatment effect. Median followup in survivors was 9 years. Competing risks regression was used to assess relationships between prognostic predictors and cause specific mortality, distant metastasis and prostate specific antigen failure.The prevalence of positive biopsy, treatment effect and negative biopsy was 30%, 22% and 48%, respectively. Androgen deprivation therapy omission and high risk disease were associated with a 2.6 and 1.8-fold increase, respectively, in the odds of positive posttreatment biopsy. The 15-year PSA relapse rate associated with negative, severe treatment effect and positive posttreatment biopsies was 34%, 36% and 79%, respectively (p0.001). After controlling for known predictors the risk of distant metastasis was 2.6-fold higher in patients with a positive biopsy (p0.001) and cause specific mortality was twice as high in patients with a positive biopsy compared to those with negative and severe treatment effect biopsy outcomes (HR 2.00, p = 0.022).A positive posttreatment biopsy after external beam radiotherapy was associated with a higher risk of distant metastasis and prostate cancer related death. Patients with severe treatment effect classified biopsies have biological characteristics more like patients with a negative biopsy than a positive biopsy. Posttreatment biopsies were more often positive in the setting of external beam radiotherapy alone without androgen deprivation therapy or in the presence of high risk disease.

Importance Ultra-high single-dose radiotherapy (SDRT) represents a potential alternative to curative extreme hypofractionated stereotactic body radiotherapy (SBRT) in organ-confined prostate cancer. Objective To compare toxic effect profiles, prostate-specific antigen (PSA) responses, and quality-of-life end points of SDRT vs extreme hypofractionated SBRT. Design, setting, and participants The PROSINT single-institution phase 2 randomized clinical trial accrued, between September 2015 and January 2017, 30 participants with intermediate-risk prostate cancer to receive SDRT or extreme hypofractionated SBRT. Androgen deprivation therapy was not permitted. Data were analyzed from March to May 2020. Interventions Patients were randomized in a 1:1 ratio to receive 5 × 9 Gy SBRT (control arm) or 24 Gy SDRT (test arm). Main outcomes and measures The primary end point was toxic effects; the secondary end points were PSA response, PSA relapse-free survival, and patient-reported quality of life measured with the International Prostate Symptom Score (IPSS) and Expanded Prostate Cancer Index Composite (EPIC)-26 questionnaires. Results A total of 30 men were randomized; median (interquartile range) age was 66.3 (61.2-69.9) and 73.6 (64.7-75.9) years for the SBRT and SDRT arms, respectively. Time to appearance and duration of acute and late toxic effects were similar in the 2 trial arms. Cumulative late actuarial urinary toxic effects did not differ for grade 1 (hazard ratio [HR], 0.41; 90% CI, 0.13-1.27) and grade 2 or greater (HR, 1.07; 90% CI, 0.21-5.57). Actuarial grade 1 late gastrointestinal (GI) toxic effects were comparable (HR, 0.37; 90% CI, 0.07-1.94) and there were no grade 2 or greater late GI toxic effects. Declines in PSA level to less than 0.5 ng/mL occurred by 36 months in both study arms. No PSA relapses occurred in favorable intermediate-risk disease, while in the unfavorable category, the actuarial 4-year PSA relapse-free survival values were 75.0% vs 64.0% (HR, 0.76; 90% CI, 0.17-3.31) for SBRT vs SDRT, respectively. The EPIC-26 median summary scores for the genitourinary and GI domains dropped transiently at 1 month and returned to pretreatment scores by 3 months in both arms. The IPSS-derived transient late urinary flare symptoms occurred at 9 to 18 months in 20% (90% CI, 3%-37%) of patients receiving SDRT. Conclusions and relevance In this randomized clinical trial among patients with intermediate-risk prostate cancer, SDRT was safe and associated with low toxicity, and the tumor control and quality-of-life end points closely match the SBRT arm outcomes. Further studies are encouraged to explore indications for SDRT in the cure of prostate cancer. Trial registration ClinicalTrials.gov Identifier: NCT02570919.

Purpose The current oligometastatic (OM) model postulates that the disease evolves dynamically with sequential emergence of OM (SOM) lesions requiring successive rounds of SOM ablation to afford tumor cure. The present phase 2 study explores the ablative efficacy of 24 Gy single-dose radiation therapy (SDRT), its feasibility in diverse OM settings, and the impact of radioablation on polymetastatic (PM) dissemination. Methods and Materials One hundred seventy-five consecutive patients with 566 OM or SOM lesions underwent periodic positron emission tomography/computed tomography (PET/CT) imaging to stage the disease before treatment, determine tumor response, and monitor timing of PM conversion after SDRT. When 24 Gy SDRT was restricted by dose or volume constraints of serial normal organs, radioablation was diverted to a nontoxic 3×9 Gy SBRT schedule. Results SOM/SOMA occurred in 42% of the patients, and 24 Gy SDRT was feasible in 76% of the lesions. Despite 92% actuarial 5-year OM ablation by 24 Gy SDRT, respective PM-free survival (PMFS) was 26%, indicating PM conversion dominates over effective OM radioablation in many patients. Multivariate analysis of OM metrics derived from staging PET/CT scanning before first treatment predicted PMFS outcome after SDRT. Bivariate analysis of dichotomized high versus low baseline metric combinations of CT-derived tumor load (cutoff at 14.8 cm3) and PET-derived metabolic SUVmax (cutoff at 6.5) yielded a 3-tiered PMFS categorization of 89%, 58% and 17% actuarial 5-year PMFS in categories 1, 2, and 3, respectively (P Conclusion Long-term risk of PM dissemination, predicted by preablation PET/CT staging, provides guidelines for phenotype-oriented OM therapy. In categories 1 and 2, radioablation should be a primary therapeutic element when pursuing tumor cure, whereas in the PM-prone category 3, radioablation should be a component of multimodal trials addressing primarily the risk of PM dissemination. PET/CT baseline staging also provides a platform for discovery of pharmacologically accessible PM drivers as targets for new phenotype-oriented treatment protocols.

Stem cells of the small and large intestine are marked by expression of the Wnt target gene LGR5, a leucine-rich-repeat-containing G protein-coupled receptor. Previous studies reported increased expression of LGR5 in human colorectal cancer (CRC) compared to normal tissue either by immunohistochemistry or in situ hybridization (ISH). However, as these studies were semi-quantitative they did not provide a numerical estimate of the magnitude of this effect. While we confirm that LGR5+ cells are exclusively located at the base of normal human small and large intestinal crypts, representing approximately 6% of total crypt cells, we show this cell population is 10-fold expanded in all grades of CRC, representing as much as 70% of the cells of tumor crypt-like structures. This expansion of the LGR5 compartment coincides with maintenance of crypt-like glandular structure (adenomas, and well and moderately differentiated adenocarcinomas), and is reduced in poorly differentiated CRC, where crypt-like glandular architecture is lost, accompanied by reduced epithelial terminal differentiation. Altogether these results indicate that LGR5+ cell expansion is a hallmark of CRC tumorigenesis occurring during progression to adenoma, supporting CRC as a stem cell disease with implications for CRC therapy.

Despite great promise, combining anti-angiogenic and conventional anti-cancer drugs has produced limited therapeutic benefit in clinical trials, presumably because mechanisms of anti-angiogenic tissue response remain only partially understood. Here we define a new paradigm, in which anti-angiogenic drugs can be used to chemosensitize tumors by targeting the endothelial acid sphingomyelinase (ASMase) signal transduction pathway. We demonstrate that paclitaxel and etoposide, but not cisplatin, confer ASMase-mediated endothelial injury within minutes. This rapid reaction is required for human HCT-116 colon cancer xenograft complete response and growth delay. Whereas VEGF inhibits ASMase, anti-VEGFR2 antibodies de-repress ASMase, enhancing endothelial apoptosis and drug-induced tumor response in asmase+/+, but not in asmase−/−, hosts. Such chemosensitization occurs only if the anti-angiogenic drug is delivered 1–2 hours before chemotherapy, but at no other time prior to or post chemotherapy. Our studies suggest that precisely-timed administration of anti-angiogenic drugs in combination with ASMase-targeting anti-cancer drugs is likely to optimize anti-tumor effects of systemic chemotherapy. This strategy warrants evaluation in future clinical trials.

Mammalian NOTCH1-4 receptors are all associated with human malignancy, although exact roles remain enigmatic. Here we employ glp-1(ar202), a temperature-sensitive gain-of-function C. elegans NOTCH mutant, to delineate NOTCH-driven tumor responses to radiotherapy. At ≤20°C, glp-1(ar202) is wild-type, whereas at 25°C it forms a germline stem cell⁄progenitor cell tumor reminiscent of human cancer. We identify a NOTCH tumor phenotype in which all tumor cells traffic rapidly to G2⁄M post-irradiation, attempt to repair DNA strand breaks exclusively via homology-driven repair, and when this fails die by mitotic death. Homology-driven repair inactivation is dramatically radiosensitizing. We show that these concepts translate directly to human cancer models.

Radiation gastrointestinal (GI) syndrome is a major lethal toxicity that may occur after a radiation/nuclear incident. Currently, there are no prophylactic countermeasures against radiation GI syndrome lethality for first responders, military personnel, or remediation workers entering a contaminated area. The pathophysiology of this syndrome requires depletion of stem cell clonogens (SCCs) within the crypts of Lieberkühn, which are a subset of cells necessary for postinjury regeneration of gut epithelium. Recent evidence indicates that SCC depletion is not exclusively a result of DNA damage but is critically coupled to ceramide-induced endothelial cell apoptosis within the mucosal microvascular network. Here we show that ceramide generated on the surface of endothelium coalesces to form ceramide-rich platforms that transmit an apoptotic signal. Moreover, we report the generation of 2A2, an anti-ceramide monoclonal antibody that binds to ceramide to prevent platform formation on the surface of irradiated endothelial cells of the murine GI tract. Consequently, we found that 2A2 protected against endothelial apoptosis in the small intestinal lamina propria and facilitated recovery of crypt SCCs, preventing the death of mice from radiation GI syndrome after high radiation doses. As such, we suggest that 2A2 represents a prototype of a new class of anti-ceramide therapeutics and an effective countermeasure against radiation GI syndrome mortality.

To report tumor local control after treatment with single-dose image-guided intensity-modulated radiotherapy (SD-IGRT) to extracranial metastatic sites.A total of 126 metastases in 103 patients were treated with SD-IGRT to prescription doses of 18-24 Gy (median, 24 Gy) between 2004 and 2007.The overall actuarial local relapse-free survival (LRFS) rate was 64% at a median follow-up of 18 months (range, 2-45 months). The median time to failure was 9.6 months (range, 1-23 months). On univariate analysis, LRFS was significantly correlated with prescription dose (p = 0.029). Stratification by dose into high (23 to 24 Gy), intermediate (21 to 22 Gy), and low (18 to 20 Gy) dose levels revealed highly significant differences in LRFS between high (82%) and low doses (25%) (p0.0001). Overall, histology had no significant effect on LRFS (p = 0.16). Renal cell histology displayed a profound dose-response effect, with 80% LRFS at the high dose level (23 to 24 Gy) vs. 37% with low doses (≤22 Gy) (p = 0.04). However, for patients who received the high dose level, histology was not a statistically significant predictor of LRFS (p = 0.90). Target organ (bone vs. lymph node vs. soft tissues) (p = 0.5) and planning target volume size (p = 0.55) were not found to be associated with long-term LRFS probability. Multivariate Cox regression analysis confirmed prescription dose to be a significant predictor of LRFS (p = 0.003).High-dose SD-IGRT is a noninvasive procedure resulting in high probability of local tumor control. Single-dose IGRT may be effectively used to locally control metastatic deposits regardless of histology and target organ, provided sufficiently high doses (22 Gy) of radiation are delivered.

We previously demonstrated that treatment of human androgen-responsive prostate cancer cell lines LNCaP and CWR22-Rv1 with 12-O-tetradecanoylphorbol 13-acetate (TPA), a known protein kinase C (PKC) activator, decreases ATM protein levels, thus de-repressing the enzyme ceramide synthase (CS) and promoting apoptosis as well as radio-sensitizing these cells.(1) Here we show that PKCalpha mediates the TPA effect on ATM expression, since ATM suppression and apoptosis induced by either TPA or diacylglycerol-lactone (DAG-lactone), both inducing PKCalpha activation,(2) are abrogated in LNCaP cells following transfection of a kinase-dead PKCalpha mutant (KD-PKCalpha). Similarly, KD-PKCalpha blocks the apoptotic response elicited by combination of TPA and radiation, whereas expression of constitutively active PKCalpha is sufficient to sensitize cells to radiation alone, without a need to pre-treat the cells with TPA. These findings identify CS activation as a downstream event of PKCalpha activity in LNCaP cells. Similar results were obtained in CWR22-Rv1 cells with DAG-lactone treatment. Using the LNCaP orthotopic prostate model it is shown that treatment with TPA or DAG-lactone induces significant reduction in tumor ATM levels coupled with tumor growth delay. Furthermore, while fractionated radiation alone produces significant tumor growth delay, pretreatment with TPA or DAG-lactone significantly potentiates tumor cure. These findings support a model in which activation of PKCalpha downregulates ATM, thus relieving CS repression by ATM and enhancing apoptosis via ceramide generation. This model may provide a basis for the design of new therapies in prostate cancer.

While antisense oligonucleotide (AS-ODN) technology holds promise for the treatment of cancer, to date there have been no clinical successes. Unfortunately, current assays are not sufficiently sensitive to measure tissue ODN levels. Hence it has not been possible to ascertain whether treatment failures result from failure of drug delivery. To investigate the relationship between drug uptake and therapeutic effect, we developed an ultrasensitive noncompetitive hybridization-ligation enzyme-linked immunosorbent assay (NCHL-ELISA) to quantify Kinase Suppressor of Ras1 (KSR1) AS-ODN drug uptake in plasma and tumor tissues. In mice harboring PANC-1 pancreatic cancer xenografts and continuously infused with AS-ODN, our ELISA detects plasma and tumor KSR1 AS-ODN levels over an extended range, from 0.05 nM to 20 nM. Using this sensitive assay, we demonstrate that KSR1 repression in pancreatic cancer xenografts correlates highly with AS-ODN uptake into tumor tissues. In contrast, plasma drug levels do not correlate with tumor drug content or target downregulation. These studies indicate the efficacy of our ELISA, and suggest that tumor biopsy material will need to be procured to estimate the potential of this antisense technology.

Purpose To report tumor control and toxicity for patients treated with image-guided intensity-modulated radiotherapy (RT) for spinal metastases with high-dose single-fraction RT. Methods and Materials A total of 103 consecutive spinal metastases in 93 patients without high-grade epidural spinal cord compression were treated with image-guided intensity-modulated RT to doses of 18–24 Gy (median, 24 Gy) in a single fraction between 2003 and 2006. The spinal cord dose was limited to a 14-Gy maximal dose. The patients were prospectively examined every 3–4 months with clinical assessment and cross-sectional imaging. Results The overall actuarial local control rate was 90% (local failure developed in 7 patients) at a median follow-up of 15 months (range, 2–45 months). The median time to local failure was 9 months (range, 2–15 months) from the time of treatment. Of the 93 patients, 37 died. The median overall survival was 15 months. In all cases, death was from progression of systemic disease and not local failure. The histologic type was not a statistically significant predictor of survival or local control. The radiation dose was a significant predictor of local control (p = 0.03). All patients without local failure also reported durable symptom palliation. Acute toxicity was mild (Grade 1-2). No case of radiculopathy or myelopathy has developed. Conclusion High-dose, single-fraction image-guided intensity-modulated RT is a noninvasive intervention that appears to be safe and very effective palliation for patients with spinal metastases, with minimal negative effects on quality of life and a high probability of tumor control.

To report toxicity and preliminary biochemical outcomes with high-dose intensity-modulated radiation therapy (IMRT) to a dose of 86.4 Gy for localized prostate cancer.Between August 1997 and March 2004, 478 patients were treated with 86.4 Gy using a 5- to 7-field IMRT technique. To adhere to normal tissue constraints, the mean D95 and V100 for the planning target volume were 83 Gy and 87%, respectively. Toxicity data were scored according to the Common Terminology Criteria for Adverse Events Version 3.0. Freedom from biochemical relapse was calculated. The median follow-up was 53 months.Thirty-seven patients (8%) experienced acute Grade 2 gastrointestinal (GI) toxicity. There was no acute Grade 3 or 4 GI toxicity. One hundred and five patients (22%) experienced acute Grade 2 genitourinary (GU) toxicity and three patients (0.6%) had Grade 3 GU toxicity. There was no acute Grade 4 GU toxicity. Sixteen patients (3%) developed late Grade 2 GI toxicity and two patients (1%) developed late Grade 3 GI toxicity. Sixty patients (13%) had late Grade 2 GU toxicity and 12 (3%) experienced late Grade 3 GU toxicity. The 5-year actuarial PSA relapse-free survival according to the nadir plus 2 ng/mL definition was 98%, 85% and 70% for the low, intermediate, and high risk NCCN prognostic groups.This report represents the largest data set of patients treated to ultra-high radiation dose levels of 86.4 Gy using IMRT for localized prostate cancer. Our findings indicate that this treatment is well tolerated and the early excellent biochemical control rates are encouraging.

We report local control outcomes, as assessed by posttreatment biopsies in patients who underwent 3-dimensional conformal radiotherapy for clinically localized prostate cancer. In addition, we report the influence of local tumor control on long-term distant metastases and cause specific survival outcomes.Posttreatment prostate biopsies were performed in 339 patients who underwent 3-dimensional conformal radiotherapy for clinically localized prostate cancer. The histological outcome of prostate biopsy was classified as positive-prostatic adenocarcinoma without typical radiation induced changes or negative-no evidence of carcinoma or severe treatment effect. Median followup in this group of 339 patients was 10 years after the completion of treatment and 6.25 years after posttreatment biopsy.Overall biopsy outcomes in these patients were positive in 32%, severe treatment effect in 21% and negative in 47%. A higher radiation dose in the intermediate and high risk subgroups was associated with a lower incidence of positive biopsy. Of patients at intermediate risk who received a dose of 75.6 or greater 24% had a positive biopsy compared to 42% who received 70.2 Gy or less (p = 0.03). In the high risk group positive treatment biopsies were noted in 51% of patients who received 70.2 Gy or less, 33% of those who received 75.6 Gy and 15% of those who received 81 Gy or greater (70.2 or less vs 75.6 Gy p = 0.07 and 75.6 vs 81 Gy or greater p = 0.05). Short course neoadjuvant androgen deprivation therapy before 3-dimensional conformal radiotherapy had a significant impact on the posttreatment biopsy outcome. Of patients who did not receive androgen deprivation therapy 42% had a positive biopsy compared to 16% who received androgen deprivation therapy (p0.0001). Patients with negative and severe treatment effect biopsies had similar 10-year prostate specific antigen relapse-free survival outcomes that were markedly different from outcomes in those with positive treatment biopsies. Multivariate analysis indicated that the strongest predictor of biochemical failure was posttreatment biopsy status (positive vs severe treatment effect or negative p0.001), followed by pretreatment prostate specific antigen (p = 0.05) and clinical T stage (p = 0.09). Similarly multivariate analysis revealed that a positive posttreatment biopsy was one of the strongest predictors of distant metastasis and prostate cancer death in this cohort of patients.As assessed by posttreatment prostate biopsies, local control is improved with higher radiation doses. Long-term biochemical outcomes in patients with posttreatment biopsies demonstrating severe treatment effect changes were not different than those in patients with negative biopsies. We also noted that local tumor control was associated with a decrease in distant metastases and prostate cancer mortality, further highlighting the importance of achieving optimal tumor control in patients with clinically localized disease.

To investigate the correlations between observed clinical morbidity and dosimetric parameters for whole pelvic radiotherapy (WPRT) for prostate cancer using either three-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT).Between December 1996 and January 2002, 27 patients with prostate adenocarcinoma were treated with conformal WPRT as part of their definitive treatment. WPRT was delivered with 3D-CRT in 14 patients and with IMRT in 13 patients. For each of the patients treated with IMRT, optimized conventional two-dimensional (2D) and 3D-CRT plans were retrospectively generated for the whole pelvic phase of the treatment. Dose-volume histograms for the bowel, bladder, and rectum were compared for the three techniques. Acute toxicities were evaluated for all 27 patients, and late toxicities were evaluated for 25 patients with sufficient follow-up. Toxicities were scored according to the Radiation Therapy Oncology Group morbidity grading scales. Median follow-up was 30 months.Three-dimensional-CRT resulted in a 40% relative reduction (p0.001) in the volume of bowel receiving 45 Gy compared with 2D, and IMRT provided a further 60% reduction relative to 3D-CRT (p0.001). Compared with either 2D or 3D-CRT, IMRT reduced the volume of rectum receiving 45 Gy by 90% (p0.001). Overall, 9 patients (33%) experienced acute Grade 2 gastrointestinal (GI) toxicity, and only 1 of these patients was treated with IMRT. Antidiarrhea medication was required for 6 patients (22%). However, 5 of these 6 patients also received chemotherapy, and none were treated with IMRT. No Grade 3 or higher acute or late GI toxicities were observed. No cases of late radiation enteritis were observed. Acute and late genitourinary toxicity did not appear significantly increased by the addition of conformal WPRT.Compared to conventional 2D planning, conformal planning for WPRT resulted in significant reductions in the doses delivered to the bowel, rectum, and bladder. IMRT was superior to 3D-CRT in limiting the volume of bowel and rectum within high-dose regions. These dosimetric findings correlated with low rates of acute and late GI morbidity.

Recent evidence suggests clustering of plasma membrane rafts into ceramide-enriched platforms serves as a transmembrane signaling mechanism for a subset of cell surface receptors and environmental stresses (Grassme, H., Jekle, A., Riehle, A., Schwarz, H., Berger, J., Sandhoff, K., Kolesnick, R., and Gulbins, E. (2001) J. Biol. Chem. 276, 20589-20596; Cremesti, A., Paris, F., Grassme, H., Holler, N., Tschopp, J., Fuks, Z., Gulbins, E., and Kolesnick, R. (2001) J. Biol. Chem. 276, 23954-23961). Translocation of the secretory form of acid sphingomyelinase (ASMase) into microscopic rafts generates therein the ceramide that drives raft coalescence. This process serves to feed forward Fas activation, with approximately 2% of full caspase 8 activation sufficient for maximal ASMase translocation, leading to death-inducing signaling complex formation within ceramide-rich platforms, and apoptosis. Here we report that treatment of Jurkat T cells with UV-C also induces ASMase translocation into rafts within 1 min, catalyzing sphingomyelin hydrolysis to ceramide and raft clustering. In contrast to Fas, UV-induced ASMase translocation and activation were caspase-independent. Nonetheless, ceramide-rich platforms promoted UV-C-induced death signaling, because ASMase inhibition or raft disruption inhibited apoptosis, improving clonogenic cell survival. These studies thus define two distinct mechanisms for biologically relevant ASMase activation within rafts; a Fas-mediated mechanism dependent upon caspase 8 and FADD, and a UV-induced mechanism independent of caspase activation. Consistent with this notion, genetic depletion or pharmacologic inhibition of caspase 8 or FADD, which render Jurkat cells incapable of sphingolipid signaling and apoptosis upon Fas ligation, did not impair these events upon UV-C stimulation.

Treatment with the protein kinase C activator 12-O tetradecanoylphorbol 12-acetate (TPA) enables radiation-resistant LNCaP human prostate cancer cells to undergo radiation-induced apoptosis, mediated via activation of the enzyme ceramide synthase (CS) and de novo synthesis of the sphingolipid ceramide (Garzotto, M., Haimovitz-Friedman, A., Liao, W. C., White-Jones, M., Huryk, R., Heston, D. W. W., Cardon-Cardo, C., Kolesnick, R., and Fuks, Z. (1999) Cancer Res. 59, 5194-5201). Here, we show that TPA functions to decrease the cellular level of the ATM (ataxia telangiectasia mutated) protein, known to repress CS activation (Liao, W.-C., Haimovitz-Friedman, A., Persaud, R., McLoughlin, M., Ehleiter, D., Zhang, N., Gatei, M., Lavin, M., Kolesnick, R., and Fuks, Z. (1999) J. Biol. Chem. 274, 17908-17917). Gel shift analysis in LNCaP and CWR22-Rv1 cells demonstrated a significant reduction in DNA binding of the Sp1 transcription factor to the ATM promoter, and quantitative reverse transcription-PCR showed a 50% reduction of ATM mRNA between 8 and 16 h of TPA treatment, indicating that TPA inhibits ATM transcription. Furthermore, treatment of LNCaP, CWR22-Rv1, PC-3, and DU-145 human prostate cells with antisense-ATM oligonucleotides, which markedly reduced cellular ATM levels, significantly enhanced radiation-induced CS activation and apoptosis, leading to apoptosis at doses as a low as 1 gray. These data suggest that the CS pathway initiates a generic mode of radiation-induced apoptosis in human prostate cancer cells, regulated by a suppressive function of ATM, and that ATM might represent a potential target for pharmacologic inactivation with potential clinical applications in human prostate cancer.

Purpose To identify predictors of distant metastases (DM) among patients who develop an isolated prostate-specific antigen (PSA) relapse after definitive external-beam radiotherapy for clinically localized prostate cancer. Materials and Methods A total of 1,650 patients with clinical stage T1 to T3 prostate cancer were treated with high-dose three-dimensional conformal radiotherapy. Of these, 381 patients subsequently developed three consecutive increasing PSA values and were characterized as having a biochemical relapse. The median follow-up time was 92 months from the completion of radiotherapy. Results The 5-year incidence of DM after an established PSA relapse was 29%. In a multivariate analysis, PSA doubling time (PSA-DT; P < .001), the clinical T stage (P < .001), and Gleason score (P = .007) were independent variables predicting for DM after established biochemical failure. The PSA-DT for favorable-, intermediate-, and unfavorable-risk patients who developed a biochemical failure was 20.0, 13.2, and 8.2 months, respectively (P < .001). The 3-year incidence of DM for patients with PSA-DT of 0 to 3, 3 to 6, 6 to 12, and more than 12 months was 49%, 41%, 20%, and 7%, respectively (P < .001). Patients with PSA-DT of 0 to 3 and 3 to 6 months demonstrated a 7.0 and 6.6 increased hazard of developing DM or death, respectively, compared with patients with a DT more than 12 months. Conclusion In addition to clinical stage and Gleason score, PSA-DT was a powerful predictor of DM among patients who develop an isolated PSA relapse after external-beam radiotherapy for prostate cancer. Patients who develop biochemical relapse with PSA-DT ≤ 6 months should be considered for systemic therapy or experimental protocols because of the high propensity for rapid DM development.

The relative inability of conventional radiotherapy to control localized prostate cancer results from resistance of subpopulations of tumor clonogens to dose levels of 65 to 70 Gy, the maximum feasible with traditional two-dimensional (2D) treatment planning and delivery techniques. Several technological advances have enhanced the precision and improved the outcome of external-beam radiotherapy. The three-dimensional conformal radiotherapy (3D-CRT) approach has permitted significant increases in the tumor dose to levels beyond those feasible with conventional techniques. Intensity-modulated radiotherapy (IMRT), an advanced form of conformal radiotherapy, has resulted in reduced rectal toxicity, permitting tumor dose escalation to previously unattainable levels with a concomitant improvement in local tumor control and disease-free survival. The combination of androgen deprivation and conventional-dose radiotherapy, tested mainly in patients with locally advanced disease, has also produced significant outcome improvements. Whether androgen deprivation will preclude the need for dose escalation or whether high-dose radiotherapy will obviate the need for androgen deprivation remains unknown. In some patients, both approaches may be necessary to maximize the probability of cure. In view of the favorable benefit-risk ratio of high-dose IMRT, the design of clinical trials to resolve these critical questions is essential.

Background and purpose : To assess the effect of internal organ motion on the dose distributions and biological indices for the target and non-target organs for three different conformal prostate treatment techniques. Materials and methods : We examined three types of treatment plans in 20 patients: (1) a six field plan, with a prescribed dose of 75.6 Gy; (2) the same six field plan to 72 Gy followed by a boost to 81 Gy; and (3) a five field plan with intensity modulated beams delivering 81 Gy. Treatment plans were designed using an initial CT data set (planning) and applied to three subsequent CT scans (treatment). The treatment CT contours were used to represent patient specific organ displacement; in addition, the dose distribution was convolved with a Gaussian distribution to model random setup error. Dose–volume histograms were calculated using an organ deformation model in which the movement between scans of individual points interior to the organs was tracked and the dose accumulated. The tumor control probability (TCP) for the prostate and proximal half of seminal vesicles (clinical target volume, CTV), normal tissue complication probability (NTCP) for the rectum and the percent volume of bladder wall receiving at least 75 Gy were calculated. Results : The patient averaged increase in the planned TCP between plan types 2 and 1 and types 3 and 1 was 9.8% (range 4.9–12.5%) for both, whereas the corresponding increases in treatment TCP were 9.0% (1.3–16%) and 8.1% (−1.3–13.8%). In all patients, plans 2 and 3 (81 Gy) exhibited equal or higher treatment TCP than plan 1 (75.6 Gy). The maximum treatment NTCP for rectum never exceeded the planning constraint and percent volume of bladder wall receiving at least 75 Gy was similar in the planning and treatment scans for all three plans. Conclusion : For plans that deliver a uniform prescribed dose to the planning target volume (PTV) (plan 1), current margins are adequate. In plans that further escalate the dose to part of the PTV (plans 2 and 3), in a fraction of the cases the CTV dose increase is less than planned, yet in all cases the TCP values are higher relative to the uniform dose PTV (plan 1). Doses to critical organs remain within the planning criteria.

Background and purpose: We fit phenomenological tumor control probability (TCP) models to biopsy outcome after three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer patients to quantify the local dose–response of prostate cancer. Materials and methods: We analyzed the outcome after photon beam 3D-CRT of 103 patients with stage T1c-T3 prostate cancer treated at Memorial Sloan-Kettering Cancer Center (MSKCC) (prescribed target doses between 64.8 and 81 Gy) who had a prostate biopsy performed $2.5 years after end of treatment. A univariate logistic regression model based on Dmean (mean dose in the planning target volume of each patient) was fit to the whole data set and separately to subgroups characterized by low and high values of tumor-related prognostic factors Tstage (,T2c vs. $T2c), Gleason score (#6 vs. .6), and pre-treatment prostate-specific antigen (PSA) (#10 ng/ml vs. .10 ng/ml). In addition, we evaluated five different classifications of the patients into three risk groups, based on all possible combinations of two or three prognostic factors, and fit bivariate logistic regression models with Dmean and the risk group category to all patients. Dose–response curves were characterized by TCD50, the dose to control 50% of the tumors, and g50, the normalized slope of the dose–response curve at TCD50. Results: Dmean correlates significantly with biopsy outcome in all patient subgroups and larger values of TCD50 are observed for patients with unfavorable compared to favorable prognostic factors. For example, TCD50 for high T-stage patients is 7 Gy higher than for low T-stage patients. For all evaluated risk group definitions, Dmean and the risk group category are independent predictors of biopsy outcome in bivariate analysis. The fit values of TCD50 show a clear separation of 9–10.6 Gy between low and high risk patients. The corresponding dose–response curves are steeper ðg50 ¼ 3:4–5:2Þ than those obtained when all patients are analyzed together ðg50 ¼ 2:9Þ. Conclusions: Dose–response of prostate cancer, quantified by TCD50 and g50, varies by prognostic subgroup. Our observations are consistent with the hypothesis that the shallow nature of clinically observed dose–response curves for local control result from a patient population that is a heterogeneous mixture of sub-populations with steeper dose–response curves and varying values of TCD50. Such results may eventually help to identify patients, based on their individual pre-treatment prognostic factors, that would benefit most from doseescalation, and to guide dose prescription. q 2002 Elsevier Science Ireland Ltd. All rights reserved.

Purpose: To determine the expected time to serum testosterone normalization after short-course neoadjuvant androgen deprivation therapy (NAAD) and three-dimensional conformal radiotherapy for patients with localized prostate cancer and to identify pretreatment predictors that correlated with the time to testosterone normalization. Methods: Between 1993 and 1999, 88 patients with localized prostate cancer, treated with NAAD and external beam radiotherapy, were prospectively monitored after treatment with sequential testosterone levels. NAAD was administered before and during the entire course of radiotherapy and discontinued at the end of treatment. The median duration of NAAD was 6 months. The actuarial rate of serum testosterone normalization from the end of treatment was evaluated, and the presence or absence of androgen deprivation-related symptoms was correlated with serum testosterone levels. Symptoms assessed included weight gain, loss of libido, breast tenderness, breast enlargement, hot flashes, and fatigue. Results: Serum testosterone levels returned to the normal range in 57 (65%) of the 88 patients and failed to normalize in 31 patients (35%). The median time to normalization was 18.3 months. The actuarial rate of normalization at 3, 6, 12, and 24 months was 10%, 26%, 38%, and 59%, respectively. In a multivariate analysis, a pretreatment testosterone level in the lower range of normal was the only variable that predicted for delayed testosterone normalization after NAAD ( p = 0.00047). Among 45 patients with information concerning androgen deprivation-related symptoms recorded 1 year after cessation of NAAD, 24 (53%) had normalized testosterone levels, but in 21 patients (47%), the levels had not yet returned to normal. At 1 year, only 1 (4%) of 24 patients whose testosterone level had returned to normal experienced NAAD-related symptoms compared with 14 (67%) of 21 patients who did not have normal testosterone levels ( p Conclusion: Testosterone levels often remain depressed for extended periods after cessation of short-course NAAD. Lower baseline testosterone levels predict for a delay in testosterone normalization, and the persistence of symptoms related to androgen deprivation correlates with low testosterone levels.

Recent studies suggest that trimerization of Fas is insufficient for apoptosis induction and indicate that super-aggregation of trimerized Fas might be prerequisite. For many cell surface receptors, cross-linking by multivalent ligands or antibodies induces their lateral segregation within the plasma membrane and co-localization into "caps" on one pole of the cell. In this study, we show that capping of Fas is essential for optimal function and that capping is ceramide-dependent. In Jurkat T lymphocytes and in primary cultures of hepatocytes, ceramide elevation was detected as early as 15-30 s and peaked at 1 min after CH-11 and Jo2 anti-Fas antibody treatment, respectively. Capping was detected 30 s after Fas ligation, peaked at 2 min, and was maintained at a lower level for as long as 30 min in both cell types. Ceramide generation appeared essential for capping. Acid sphingomyelinase -/- hepatocytes were defective in Jo2-induced ceramide generation, capping, and apoptosis, and nanomolar concentrations of C(16)-ceramide restored these events. To further explore the role of ceramide in capping of Fas, we employed FLAG-tagged soluble Fas ligand (sFasL), which binds trimerized Fas but is unable to induce capping or apoptosis in Jurkat cells. Cross-linking of sFasL with M2 anti-FLAG antibody induced both events. Pretreatment of cells with natural C(16)-ceramide bypassed the necessity for forced antibody cross-linking and enabled sFasL to cap and kill. The presence of intact sphingolipid-enriched membrane domains may be essential for Fas capping since their disruption with cholesterol-depleting agents abrogated capping and prevented apoptosis. These data suggest that capping is a ceramide-dependent event required for optimal Fas signaling in some cells.

Purpose and Objective: Late rectal bleeding is a potentially dose limiting complication of three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. The frequency of late rectal bleeding has been shown to increase as the prescription dose rises above 70 Gy. The purpose of this study is to identify features of the cumulative dose–volume histogram (DVH) for the rectal wall that correlate with late rectal bleeding after 3D-CRT for prostate cancer. Methods and Materials: Follow-up information on rectal bleeding is available for 261 and 315 patients treated using 3D-CRT at Memorial Sloan-Kettering Cancer Center for Stage T1c-T3 prostate cancer with minimum target doses of 70.2 and 75.6 Gy, respectively. All patients in this study were treated with a coplanar 6-field technique (2 lateral and 4 oblique fields). Patients were classified as having rectal bleeding if they bled (≥ Grade 2) before 30 months, and nonbleeding (⩽ Grade 1) if they were without bleeding at 30 months, using the RTOG morbidity scale. Rectal bleeding was observed in 13 and 38 of the patients treated at 70.2 and 75.6 Gy, respectively. Treatment plans were analyzed for 39 nonbleeding and 13 bleeding patients receiving 70.2 Gy, and 83 nonbleeding and 36 bleeding patients receiving 75.6 Gy. Dose–volume histograms (DVHs) for the anatomic rectal wall were calculated. Average DVHs of the bleeding and nonbleeding patients were generated, and a permutation test was used to assess the significance of differences between them, for each dose group. The confounding effect of total rectal wall volume (VRW) was removed by calculating the average differences in DVHs between all combinations of bleeding and nonbleeding patients with similar VRWs. Finally, multivariate analysis using logistic regression was performed to test the significance of the DVH variables in the presence of anatomic, geometric, and medical variables previously found to correlate with rectal bleeding in a companion analysis of the same patients. Results: The area under the average percent volume DVH for the rectal wall of patients with bleeding was significantly higher than those of patients without bleeding in both dose groups (p = 0.02, 70.2 Gy; p < 0.0001, 75.6 Gy). However, small VRWs were associated with rectal bleeding (p = 0.06, 70.2 Gy; p < 0.01, 75.6 Gy), resulting in an increase in average percent volumes exposed to all doses for patients with rectal bleeding. For patients with similar VRWs, rectal bleeding was significantly correlated with the volumes exposed to 46 Gy in both dose groups (p = 0.02, 70.2 Gy; p = 0.005, 75.6 Gy, tolerance in VRW: 5 ccs). For the 75.6 Gy dose group, the percent volume receiving 77 Gy was significantly correlated with rectal bleeding (p < 0.005). Bivariate analysis using logistic regression, including VRW together with a single DVH variable, showed good agreement with the above analysis. Multivariate analysis revealed a borderline significant correlation of the percent volume receiving 71 Gy in the 70.2 Gy dose group. It also showed that the DVH variables were highly correlated with geometric and dosimetric variables previously found to correlate with rectal bleeding in multivariate analysis. Conclusion: Significant volume effects were found in the probability of late rectal bleeding for patients undergoing 3D-CRT for prostate cancer with prescription doses of 70.2 and 75.6 Gy. The percent volumes exposed to 71 and 77 Gy in the 70.2 and 75.6 Gy dose groups respectively were significantly correlated with rectal bleeding. The independent correlation of small VRW with rectal bleeding may indicate the existence of a functional reserve for the rectum. The independent association with larger percent volumes exposed to intermediate doses (∼ 46 Gy) seen in both dose groups may indicate that a large surrounding region of intermediate dose may interfere with the ability to repair the effects of a central high dose region.

To investigate tumor control following three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer and to identify dose-distribution variables that correlate with local control assessed through posttreatment prostate biopsies.Data from 132 patients, treated at Memorial Sloan-Kettering Cancer Center (MSKCC), who had a prostate biopsy 2.5 years or more after 3D-CRT for T1c-T3 prostate cancer with prescription doses of 64.8-81 Gy were analyzed. Variables derived from the dose distribution in the PTV included: minimum dose (Dmin), maximum dose (Dmax), mean dose (Dmean), dose to n% of the PTV (Dn), where n = 1%,...,99%. The concept of the equivalent uniform dose (EUD) was evaluated for different values of the surviving fraction at 2 Gy (SF(2)). Four tumor control probability (TCP) models (one phenomenologic model using a logistic function and three Poisson cell kill models) were investigated using two sets of input parameters, one for low and one for high T-stage tumors. Application of both sets to all patients was also investigated. In addition, several tumor-related prognostic variables were examined (including T-stage, Gleason score). Univariate and multivariate logistic regression analyses were performed. The ability of the logistic regression models (univariate and multivariate) to predict the biopsy result correctly was tested by performing cross-validation analyses and evaluating the results in terms of receiver operating characteristic (ROC) curves.In univariate analysis, prescription dose (Dprescr), Dmax, Dmean, dose to n% of the PTV with n of 70% or less correlate with outcome (p0.01). The area under the ROC curve for Dmean is 0.64. In contrast, Dmin (p = 0.6), D98 (p = 0.2) or D95 (p = 0.1) are not significantly correlated with outcome. The results for EUD depend on the input parameter SF(2): EUD correlates significantly with outcome for SF(2) of 0.4 or more, but not for lower SF(2) values. Using either of the two input parameters sets, all TCP models correlate with outcome (p0.05; ROC areas 0.60-0.62). Using T-stage dependent input parameters, the correlation is improved (logistic function: p0.01, ROC area 0.67, Poisson models: p0.01, ROC areas 0.64-0.66). In comparison, the ROC area is 0.68 for the combination of Dmean and T-stage. After multivariate analysis, a model based on TCP, D20 and Gleason score is the best overall model (ROC area 0.73). However, an alternative model based on Dmean, Gleason score, and T-stage is competitive (ROC area 0.70).Biopsy outcome after 3D-CRT of prostate cancer at MSKCC is not correlated with Dmin in the PTV and appears to be insensitive to cold spots in the dose distribution. This observation likely reflects the fact that much of the PTV, especially at the periphery, may not contain viable tumor cells and that the treatment margins were sufficiently large. Therefore, the predictive power of all variables which are sensitive to cold spots, like TCPs with Poisson models and EUD for low SF(2), is limited because the low dose region may not coincide with the tumor location. Instead, for MSKCC prostate cancer patients with their standardized CTV definition, substantial target motion and small dose inhomogeneities, Dmean (or any variable that downplays the effect of cold spots) is a very good predictor of biopsy outcome. While our findings may indicate a general problem in the application of current TCP models to clinical data, these conclusions should not be extrapolated to other disease sites without careful analysis.

The purpose of this paper is to use the outcome of a dose escalation protocol for three-dimensional conformal radiation therapy (3D-CRT) of prostate cancer to study the dose-response for late rectal toxicity and to identify anatomic, dosimetric, and clinical factors that correlate with late rectal bleeding in multivariate analysis.Seven hundred forty-three patients with T1c-T3 prostate cancer were treated with 3D-CRT with prescribed doses of 64.8 to 81.0 Gy. The 5-year actuarial rate of late rectal toxicity was assessed using Kaplan-Meier statistics. A retrospective dosimetric analysis was performed for patients treated to 70.2 Gy (52 patients) or 75.6 Gy (119 patients) who either exhibited late rectal bleeding (RTOG Grade 2/3) within 30 months after treatment (i.e., 70.2 Gy-13 patients, 75. 6 Gy-36 patients) or were nonbleeding for at least 30 months (i.e., 70.2 Gy-39 patients, 75.6 Gy-83 patients). Univariate and multivariate logistic regression was performed to correlate late rectal bleeding with several anatomic, dosimetric, and clinical variables.A dose response for/= Grade 2 late rectal toxicity was observed. By multivariate analysis, the following factors were significantly correlated with/= Grade 2 late rectal bleeding for patients prescribed 70.2 Gy: 1) enclosure of the outer rectal contour by the 50% isodose on the isocenter slice (i.e., Iso50) (p0.02), and 2) smaller anatomically defined rectal wall volume (p0.05). After 75.6 Gy, the following factors were significant: 1) smaller anatomically defined rectal wall volume (p0.01), 2) higher rectal D(max) (p0.01), 3) enclosure of rectal contour by Iso50 (p0.01), 4) patient age (p = 0.02), and 5) history of diabetes mellitus (p = 0.04). In addition to these five factors, acute rectal toxicity was also significantly correlated (p = 0.05) with late rectal bleeding when patients from both dose groups were combined in multivariate analysis.A multivariate logistic regression model is presented which describes the probability of developing late rectal bleeding after conformal irradiation of prostate cancer. Late rectal bleeding correlated with factors which may indicate that a greater fractional volume of rectal wall was exposed to high dose, such as smaller rectal wall volume, inclusion of the rectum within the 50% isodose on the isocenter slice, and higher rectal D(max).

Although numerous studies document caspase-independent ceramide generation preceding apoptosis upon environmental stress, the molecular ordering of ceramide generation during cytokine-induced apoptosis remains uncertain. Here, we show that CD95-induced ceramide elevation occurs during the initiation phase of apoptosis. We titrated down the amount of FADD transfected into HeLa and 293T cells until it was insufficient for apoptosis, although cycloheximide (CHX) still triggered the effector phase. Even in the absence of CHX, ceramide levels increased rapidly, peaking at 2.7 +/- 0.2-fold of control 8 h post-transfection. Dominant negative FADD failed to confer ceramide generation or CHX-mediated apoptosis. Ceramide generation induced by FADD was initiator caspase-dependent, being blocked by crmA. Limited pro-caspase 8 overexpression also increased ceramide levels 2.7 +/- 0.2-fold, yet failed, without CHX, to initiate apoptosis. Expression of membrane-targeted oligomerized CD-8 caspase 8 induced apoptosis without CHX, yet elevated ceramide only to a level equivalent to limited pro-caspase 8 transfection. Ceramide elevations were detected concurrently by diacylglycerol kinase and electrospray tandem mass spectrometry. These investigations provide evidence that ceramide generation is initiator caspase-dependent and occurs prior to commitment to the effector phase of apoptosis, definitively ordering ceramide as proximal in CD95 signaling.

Purpose/Objective: This study evaluates the dosimetric benefits and feasibility of a deep inspiration breath-hold (DIBH) technique in the treatment of lung tumors. The technique has two distinct features—deep inspiration, which reduces lung density, and breath-hold, which immobilizes lung tumors, thereby allowing for reduced margins. Both of these properties can potentially reduce the amount of normal lung tissue in the high-dose region, thus reducing morbidity and improving the possibility of dose escalation. Methods and Materials: Five patients treated for non-small cell lung carcinoma (Stage IIA-IIIB) received computed tomography (CT) scans under 4 respiration conditions: free-breathing, DIBH, shallow inspiration breath-hold, and shallow expiration breath-hold. The free-breathing and DIBH scans were used to generate 3-dimensional conformal treatment plans for comparison, while the shallow inspiration and expiration scans determined the extent of tumor motion under free-breathing conditions. To acquire the breath-hold scans, the patients are brought to reproducible respiration levels using spirometry, and for DIBH, modified slow vital capacity maneuvers. Planning target volumes (PTVs) for free-breathing plans included a margin for setup error (0.75 cm) plus a margin equal to the extent of tumor motion due to respiration (1–2 cm). Planning target volumes for DIBH plans included the same margin for setup error, with a reduced margin for residual uncertainty in tumor position (0.2–0.5 cm) as determined from repeat fluoroscopic movies. To simulate the effects of respiration-gated treatments and estimate the role of target immobilization alone (i.e., without the benefit of reduced lung density), a third plan is generated from the free-breathing scan using a PTV with the same margins as for DIBH plans. Results: The treatment plan comparison suggests that, on average, the DIBH technique can reduce the volume of lung receiving more than 25 Gy by 30% compared to free-breathing plans, while respiration gating can reduce the volume by 18%. The DIBH maneuver was found to be highly reproducible, with intra breath-hold reproducibility of 1.0 (± 0.9) mm and inter breath-hold reproducibility of 2.5 (± 1.6) mm, as determined from diaphragm position. Patients were able to perform 10–13 breath-holds in one session, with a comfortable breath-hold duration of 12–16 s. Conclusion: Patients tolerate DIBH maneuvers well and can perform them in a highly reproducible fashion. Compared to conventional free-breathing treatment, the DIBH technique benefits from reduced margins, as a result of the suppressed target motion, as well as a decreased lung density; both contribute to moving normal lung tissue out of the high-dose region. Because less normal lung tissue is irradiated to high dose, the possibility for dose escalation is significantly improved.

DNA double-stranded breaks (dsb) activate surveillance systems that identify DNA damage and either initiate repair or signal cell death. Failure of cells to undergo appropriate death in response to DNA damage leads to misrepair, mutations, and neoplastic transformation. Pathways linking DNA dsb to reproductive or apoptotic death are virtually unknown. Here we report that metabolic incorporation of 125I-labeled 5-iodo-2'deoxyuridine, which produces DNA dsb, signaled de novo ceramide synthesis by post-translational activation of ceramide synthase (CS) and apoptosis. CS activation was obligatory, since fumonisin B1, a fungal pathogen that acts as a specific CS inhibitor, abrogated DNA damage-induced death. X-irradiation yielded similar results. Furthermore, inhibition of apoptosis using the peptide caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone did not affect CS activation, indicating this event is not a consequence of induction of apoptosis. ATM, the gene mutated in ataxia telangiectasia, is a member of the phosphatidylinositol 3-kinase family that constitutes the DNA damage surveillance/repair system. Epstein-Barr virus-immortalized B cell lines from six ataxia telangiectasia patients with different mutations exhibited radiation-induced CS activation, ceramide generation, and apoptosis, whereas three lines from normal patients failed to manifest these responses. Stable transfection of wild type ATM cDNA reversed these events, whereas antisense inactivation of ataxia telangiectasia-mutated gene product in normal B cells conferred the ataxia telangiectasia phenotype. We propose that one of the functions of ataxia telangiectasia-mutated gene product is to constrain activation of CS, thereby regulating DNA damage-induced apoptosis.

BACKGROUND The current study was undertaken to evaluate the incidence and predictors of late toxicity in patients with localized prostate carcinoma treated with high dose three-dimensional conformal radiotherapy (3D-CRT). METHODS A total of 743 patients with prostate carcinoma classified as T1c–T3 were treated with 3D-CRT that targeted the prostate and seminal vesicles. A minimum tumor dose of 64.8 gray (Gy) was given to 96 patients (13%), 70.2 Gy to 266 patients (365), 75.6 Gy to 320 patients (43%), and 81.0 Gy to 61 patients (8%). The median follow-up time was 42 months (range, 18–109 months). Late toxicity was graded according to the Radiation Therapy Oncology Group morbidity scoring scale. RESULTS Late gastrointestinal (GI) and urinary (GU) toxicities were absent or minimal (Grade 0 or 1) in 90% of patients. The 5-year actuarial likelihood of the development of Grade 2 and 3 late GI toxicities was 11% and 0.75%, respectively. A multivariate analysis identified doses ≥75.6 Gy (P < 0.001), history of diabetes mellitus (P = 0.01), and the presence of acute GI symptoms during treatment (P = 0.02) as independent predictors of Grade ≥2 late GI toxicity. The 5-year actuarial likelihood of the development of Grade 2 and 3 late GU toxicities was 10% and 3%, respectively. Doses ≥75.6 Gy (P = 0.008) and acute GU symptoms (P < 0.001) were independent predictors of Grade ≥2 late GU toxicity. Among 544 patients who were potent before treatment (73% of all patients), 211 (39%) became impotent after 3D-CRT. The 5-year actuarial risk of potency loss was 60%. Doses ≥75.6 Gy (P < 0.001) and the use of neoadjuvant androgen deprivation (P = 0.01) were independent predictors of posttreatment erectile dysfunction. CONCLUSIONS The incidence of severe late complications after high dose 3D-CRT was minimal. Radiation doses ≥75.6 Gy and the presence of acute treatment-related symptoms during 3D-CRT correlated with a higher incidence of Grade ≥2 late GI and GU toxicities. In addition to higher doses, the use of androgen deprivation therapy increased the likelihood of permanent impotence in these patients. Intensity-modulated radiotherapy, which makes it possible to enhance the conformality of the dose distribution, has recently been implemented in an attempt to reduce the incidence of moderate grade toxicities in patients receiving high dose 3D-CRT. Cancer 1999;85:2460–8. © 1999 American Cancer Society.

To determine the extent and predictors for prostatic motion in a large number of patients evaluated with multiple CT scans during radiotherapy, and evaluate the implications of these data on the design of appropriate treatment margins for patients receiving high-dose three-dimensional conformal radiotherapy.Fifty patients underwent four serial computerized tomography (CT) scans, consisting of an initial planning scan and subsequent scans at the beginning, middle, and end of the treatment course. Each scan was performed with the patient in the prone treatment position within an immobilization device used during therapy. Contours of the prostate and seminal vesicles were drawn on the axial CT slices of each scan, and the scans were matched by alignment of the pelvic bones with a chamfer matching algorithm. Using the contour information, distributions of the displacement of the organ center of mass and organ border from the planning position were determined separately for the prostate and seminal vesicles in each of the three principle directions: anterior-posterior (AP), superior-inferior (SI) and left-right (LR). Each distribution was fitted to a normal (Gaussian) distribution to determine confidence limits in the center of mass and border displacements and thereby evaluate for the optimal margins needed to contain target motion.The most common directions of displacement of the prostate center of mass (COM) were in the AP and SI directions and were significantly larger than any LR movement. The mean prostate COM displacement (+/- 1 standard deviation, SD) for the entire population was -1.2 +/- 2.9 mm, -0.5 +/- 3.3 mm and -0.6 +/- 0.8 mm in the, AP and SI and LR directions respectively (negative values indicate posterior, inferior or left displacement). The mean (+/- 1 SD) seminal vesicle COM displacement for the entire population was - 1.4 +/- 4.9 mm, 1.3 +/- 5.5 mm and -0.8 +/- 3.1 mm in the AP and SI and LR directions, respectively. The data indicate a tendency for the population towards posterior displacements of the prostate from the planning position and both posterior and superior displacements of the seminal vesicles. AP movement of both the prostate and seminal vesicles were correlated with changes in rectal volume (P = 0.0014 and0.0001, respectively) more than with changes in bladder volume (P = 0.030 for seminal vesicles and 0.19 for prostate). A logistic regression analysis identified the combination of rectal volume60 cm3 and bladder volumes40 cm3 as the only predictor of large (3 mm) systematic deviations for the prostate and seminal vesicles (P = 0.05) defined for each patient as the difference between organ position in the planning scan and mean position as calculated from the three subsequent scans.Prostatic displacement during a course of radiotherapy is more pronounced among patients with initial planning scans with large rectal and bladder volumes. Such patients may require more generous margins around the CTV to assure its enclosure within the prescription dose region. Identification and correction of patients with large systematic errors will minimize the extent of the margin required and decrease the volume of normal tissue exposed to higher radiation doses.

An unexpected benefit of functional genomic screens is that at times they answer questions that they were not designed to ask. A siRNA screen reported by Swanton et al. in this issue of Cancer Cell reveals that silencing of spindle assembly checkpoint genes facilitates mitotic slippage, resulting in escape from taxane-induced cell death, aneuploidy, and chromosomal instability, hallmarks of taxane resistance. Unexpectedly, the screen disclosed that the sphingolipid ceramide is a key regulator of the taxane-mediated spindle assembly checkpoint and taxane-induced cell death. Ceramide metabolism thus serves as a legitimate target for modulation of taxane effect on tumors.

To determine the long-term effects of 75.6- and 81.0-Gy doses of three-dimensional conformal radiation therapy in a dose-escalation study in patients with stage T2c-T3 prostatic cancer.Fifty patients received an initial 75.6-Gy dose, and the dose in 46 patients was subsequently escalated to 81.0-Gy. Median follow-up was 60 and 40 months, respectively.The rates of effects of acute toxicity during the course of treatment were similar for both dose levels. Among the 96 patients, the rate of grade 2 morbidities necessitating medication to relieve acute symptoms was 17% (16 patients) for rectal and 36% (35 patients) for urinary morbidities. All other patients had either no or grade 1 morbidities. Fourteen patients (15%) developed late grade 2 rectal morbidities. There were no differences in 5-year actuarial rates of late grade 2 rectal or urinary morbidities among patients who received 75.6 Gy versus those who received 81.0 Gy. One patient treated with 81.0 Gy developed a grade 3 urethral stricture, which was resolved with dilatation.Tumor dose escalation beyond conventional radiation doses for localized prostatic cancer is feasible when delivered with three-dimensional conformal radiation therapy, with no increase in morbidity in normal tissue.

PURPOSE To identify prognostic variables that predict for improved biochemical and local control outcome in patients with localized prostatic cancer treated with neoadjuvant androgen deprivation (NAAD) and three-dimensional conformal radiotherapy (3D-CRT). MATERIALS AND METHODS Between 1989 and 1995, 213 patients with localized prostate cancer were treated with a 3-month course of NAAD that consisted of leuprolide acetate and flutamide before 3D-CRT. The purpose of NAAD in these patients was to reduce the preradiotherapy target volume so as to decrease the dose delivered to adjacent normal tissues and thereby minimize the risk of morbidity from high-dose radiotherapy. The median pretreatment prostate-specific antigen (PSA) level was 15.3 ng/mL (range, 1 to 560 ng/mL). The median 3D-CRT dose was 75.6 Gy (range, 64.8 to 81 Gy), and the median follow-up time was 3 years (range, 1 to 7 years). RESULTS The significant predictors for improved outcome as identified in a multivariate analysis included pretreatment PSA level < or = 10.0 ng/mL(P < .00), NAAD-induced preradiotherapy PSA nadir < or = 0.5 ng/mL (P < .001), and clinical stage < or = T2c (P < .04). The 5-year PSA relapse-free survival rates were 93%, 60%, and 40% for patients with pretreatment PSA levels < or = 10 ng/mL, 10 to 20 ng/mL, and greater than 20 ng/mL, respectively (P < .001). Patients with preradiotherapy nadir levels < or = 0.5 ng/mL after 3 months of NAAD experienced a 5-year PSA relapse-free survival rate of 74%, as compared with 40% for patients with higher nadir levels (P < .001). The incidence of a positive biopsy among 34 patients pretreated with androgen ablation was 12%, as compared with 39% for 117 patients treated with 3D-CRT alone who underwent a biopsy (P < .001). CONCLUSION For patients treated with NAAD and high-dose 3D-CRT, pretreatment PSA, preradiotherapy PSA nadir response, and clinical stage are important predictors of biochemical outcome. Patients with NAAD-induced PSA nadir levels greater than 0.5 ng/mL before radiotherapy are more likely to develop biochemical failure and may benefit from more aggressive therapies.

Purpose : Local failure is a major obstacle to the cure of locally advanced non small-cell lung cancer. Three-dimensional conformal radiation therapy (3-DCRT) selects optimal treatment parameters to increase dose to tumor and reduce normal tissue dose, potentially representing an enhancement of the therapeutic ratio of radiation therapy for lung cancer. We performed this analysis of 45 non-small cell lung cancer patients treated with 3-DCRT alone, to evaluate the ability of computer derived lung dose volume histograms to predict serious pulmonary toxicity, to assess the feasibility of this approach, and to examine the resulting survival. Methods : There were 28 males (62%) and 17 females (38%). The median age was 65 (range: 38–82). Tumor stage was Stage I/II in 13%, IIIa in 42%, and IIIb in 44%. The histology was squamous in 44%, adenocarcinoma in 36%, and other non-small cell histologies in the others. Only 47% of patients, had combined favorable prognostic factors (i.e. KPS ≤ 80, and ≤5% wt. loss). The median dose of radiation to gross disease was 70.2 Gy (range: 52.2–72 Gy) delivered in fractions of 1.8 Gy, 5 days per week. Results : Seven patients did not complete 3-DCRT due to disease progression outside the port. Follow-up data are mature: the median follow up of the 6 survivors is 43.5 months (35–59). Thoracic progression occurred in 46%. Median survival (all 45 patients.) is 15.7 months and survival is 32% at 2 years and 12% at 59 months. Pulmonary toxicity ≥grade 3 occurred in 9% of patients. Dose volume histograms were available in 31 patients and showed a correlation between risk of pulmonary toxicity and indices of dose to lung parenchyma. Grade 3 or higher pulmonary toxicity occurred in 38% (38) of patients with > 30% of lung volume receiving ≥25 Gy, versus 4% (123) of patients with ≤30% lung receiving ≥25 Gy ( P = 0.04). Grade 3 or higher pulmonary toxicity occurred in 29% (414) of patients with a predicted pulmonary normal tissue complication probability of 12% or higher versus 0% (0/17) in patients with a predicted probability of less than 12% ( P = 0.03). Conclusions : Despite adverse prognostic criteria median survival is encouraging and may be higher than some combined modality approaches. Dose volume histogram parameters may be useful to determine the maximum dose for individual patients and thereby permit avoidance of toxicity.

Purpose: To prospectively assess the effect of supine vs. prone treatment position on the dose to normal tissues in prostate cancer patients treated with the three-dimensional conformal technique. Methods and Materials: Twenty-six patients underwent three-dimensional treatment planning in both the supine and prone treatment positions. The planning target volume and normal tissue structures were outlined on each CAT scan slice, and treatment plans were compared to assess the effect of treatment position on the volume of rectum, bladder, and bowel exposed to the high doses of irradiation. Results: The average dose to the rectal wall and the V95 (volume of rectal wall receiving at least 95% of the prescription dose) for the prone position were 64 and 24% of the prescription dose, respectively, compared to 72 and 29%, respectively, for the supine position (p < 0.05). When the average rectal wall dose was used as an endpoint, 14 of the 26 patients (54%) had an advantage for the prone position compared to 1 (4%) who demonstrated and advantage for the supine position (p < 0.0002). Similarly, when V95 of the rectal wall was used as a measure of comparison, 15 patients (58%) had an advantage for the prone position compared to 1 (4%) who demonstrated an advantage for the supine position (p < 0.0002). In 13 patients (50%), a change from spine to the prone position was associated with reduction of the V95 to levels < 30% of the prescription dose compared to 3 patients (11%) in whom such an advantage resulted from change of the prone to the supine position (p < 0.005). The effect of treatment position on the rectal wall dose was most pronounced in the region of the seminal vesicles. An increased volume of bowel was also noted in the supine position. The treatment position, however, had no significant impact on the dose to the bladder wall. Conclusions: Three-dimensional conformal radiotherapy for prostate cancer in the prone position is associated with significant reduction of the dose to the rectum and bowel resulting in an improvement in the therapeutic ratio.

The sphingomyelin pathway is a ubiquitous, evolutionarily conserved signaling system initiated by hydrolysis of the plasma membrane phospholipid sphingomyelin to generate ceramide. Ceramide acts as a second messenger in activating the apoptotic cascade. Diverse cytokine receptors and environmental stresses utilize ceramide to signal apoptosis. In several cell systems ceramide links to the stress-activated protein kinase (SAPK)/c-jun kinase (JNK) cascade to signal apoptosis. The engagement of the sphingomyelin pathway in signaling apoptosis is tightly regulated by anti-apoptotic control mechanisms, and the balance between pro- and anti-apoptotic systems determines the magnitude of the apoptotic response in vitro and in vivo. This review describes the known elements and molecular ordering of ceramide-mediated apoptosis and the anti-apoptotic mechanisms that regulate its expression. Understanding of pro- and anti-apoptotic signaling involved in ceramide-mediated apoptosis and the modes of their co-ordinated function may yield opportunities for pharmacological interventions with potential for clinical applications.

SummaryRecent research has shed new light on the critical role of tissue microvasculature in regulating the tumor response to radiation and drugs. In this issue of Cancer Cell, Moeller et al. (2005) demonstrate that HIF-1 activation during the course of fractionated radiotherapy initiates pleiotropic adaptive responses in both tumor cells and the microvascular network, radiosensitizing tumor cells but concomitantly conferring tumor radioresistance due to protection of the microvascular endothelium. HIF-1 thus serves as a legitimate target for differential modulation of tissue response to radiation.