Search

Purpose BRCA1/2 pathogenic variant (PV) mutations confer radiation sensitivity preclinically, but there are limited data regarding breast cancer outcomes after radiation therapy (RT) among patients with documented BRCA1/2 PV mutations versus no PV mutations. Methods and Materials This retrospective cohort study included women with clinical stage I-III breast cancer who received definitive surgery and RT and underwent BRCA1/2 genetic evaluation at the The University of Texas MD Anderson Cancer Center. Rates of locoregional recurrence (LRR), disease-specific death (DSD), toxicities, and second cancers were compared by BRCA1/2 PV status. Results Of the 2213 women who underwent BRCA1/2 testing, 63% self-reported their race as White, 13.6% as Black/African American, 17.6% as Hispanic, and 5.8% as Asian/American Indian/Alaska Native; 124 had BRCA1 and 100 had BRCA2 mutations; and 1394 (63%) received regional nodal RT. The median follow-up time for all patients was 7.4 years (95% confidence interval [CI], 7.1-7.7 years). No differences were found between the groups with and without BRCA1/2 PV mutations in 10-year cumulative incidences of LRR (with mutations: 11.6% [95% CI, 7.0%-17.6%]; without mutations: 6.6% [95% CI, 5.3%-8.0%]; P = .466) and DSD (with mutations: 12.3% [95% CI, 8.0%-17.7%]; without mutations: 13.8% [95% CI, 12.0%-15.8%]; P = .716). On multivariable analysis, BRCA1/2 status was not associated with LRR or DSD, but Black/African American patients (P = .036) and Asians/American Indians/Alaska Native patients (P = .002) were at higher risk of LRR compared with White patients, and Black/African American patients were at higher risk of DSD versus White patients (P = .004). No in-field, nonbreast second cancers were observed in the BRCA1/2 PV group. Rates of acute and late grade ≥3 radiation-related toxicity in the BCRA1/2 PV group were 5.4% (n = 12) and 0.4% (n = 1), respectively. Conclusions Oncologic outcomes in a diverse cohort of patients with breast cancer who had a germline BRCA1/2 PV mutation and were treated with RT were similar to those of patients with no mutation, supporting the use of RT according to standard indications in patients with a germline BRCA1/2 PV mutation.

Despite a preponderance of data demonstrating strong clinical outcomes and cost-effectiveness, prostate brachytherapy use and competency continue to decline. Enhanced resident education may help reverse this trend. We therefore developed and implemented a simulation-based medical education course for low-dose-rate prostate brachytherapy (LDR-PB).A 1-week LDR-PB course comprised four 1-h lectures on clinical outcomes, physics, radiobiology, and anatomy/contouring, followed by a 4.5-h simulation session on ultrasound-guided prostate phantom implantation, was developed for radiation oncology residents at an academic institution. A 10-statement Likert-scale survey and 20-question multiple-choice test were administered 1 week before and 4 weeks after the course.Precourse and postcourse instruments were completed by 24 and 20 residents, respectively. The median number of prior LDR-PB cases after at least one genitourinary rotation was 10.5 (range 5-20). Overall mean test scores were significantly improved (55% before the course vs 68% after the course; p = 0.010). Mean Likert scores significantly increased on nine of 10 survey statements and were significantly increased overall (2.4 before the course vs 3.3 after the course, p0.001). When asked about interest in performing brachytherapy after residency, 37.5% of residents "agreed" or "strongly agreed" before the course vs 50% after the course (p = 0.41). Those with higher postresidency brachytherapy interest (scores of 4-5 vs 1-3) had significantly more LDR-PB cases (11.2 vs 5.3 cases; p = 0.005).A 1-week simulation-based medical education course for LDR-PB can improve didactic performance and self-reported technical competence/confidence, and may increase overall enthusiasm for brachytherapy. Future studies at our institution will incorporate evaluation of implant quality and assessment of procedural competence into this framework. Residency programs should dedicate resources to this essential component of radiation oncology.

We aimed to investigate whether implicit linguistic biases exist in letters of recommendation (LORs) for applicants to radiation oncology (RO) residency. LORs (n = 487) written for applicants (n = 125) invited to interview at a single RO residency program from the 2015 to 2019 application cycles were included for analysis. Linguistic Inquiry and Word Count (LIWC) software was used to evaluate LORs for length and a dictionary of predetermined themes. Language was evaluated for gender bias using a publicly available gender bias calculator. Non-parametric tests were used to compare linguistic domain scores. The median number of the LORs per applicant was 4 (range 3–5). No significant differences by applicant gender were detected in LIWC score domains or gender bias calculator (P > 0.05). However, LORs for applicants from racial/ethnic backgrounds underrepresented in medicine were less likely to include standout descriptors (P = 0.008). Male writers were less likely to describe applicant characteristics related to patient care (P < 0.0001) and agentic personality (P = 0.006). LORs written by RO were shorter (P < 0.0001) and included fewer standout descriptors (P = 0.014) but were also more likely to include statements regarding applicant desirability (P = 0.045) and research (P = 0.008). While language was globally male-biased, assistant professors were less likely than associate professors (P = 0.0064) and full professors (P = 0.023) to use male-biased language. Significant linguistic differences were observed in RO residency LORs, suggesting that implicit biases related to both applicants and letter writers may exist. Recognition, and ideally eradication, of such biases are crucial for fair and equitable evaluation of a diverse applicant pool of RO residency candidates. Electronic supplementary material The online version contains supplementary material available at 10.1007/s13187-020-01907-x.

Background and purpose To report physician-assessed toxicities (PATs) and patient-reported outcomes (PROs) in a prospective cohort of patients treated using proton beam therapy (PBT). Methods and materials From 2011 to 2019, PBT-treated patients with a sinonasal malignancy were enrolled with a primary endpoint of toxicity assessment. PATs and PROs were assessed at baseline, acute (during PBT), subacute (within 90 days after PBT), and chronic time points. PATs were graded with the Common Terminology Criteria for Adverse Events V4.0. PROs were assessed with the Xerostomia-Related Quality-of-Life Scale (XeQoLS), MD Anderson Dysphagia Inventory (MDADI), and Functional Assessment of Cancer Therapy (FACT). PRO changes from baseline to follow-up were defined as significantly different based on a paired t-test plus a minimal clinically important difference. Results Sixty-four patients had a median follow-up time of 33 months (interquartile range: 10–52 months). The most common histology was olfactory neuroblastoma (28%) and most patients had T4 disease (46%). One acute G3 neurologic PAT (blurred vision) resolved, and no late G3–4 neurologic PATs were observed. Feeding tube placement occurred in 6% of patients. No significant changes were noted in PROs from baseline to the chronic period. Significant worsening from baseline was noted in the XeQoLS acute-subacute physical functioning, pain, personal/psychological distress, and social function; acute-subacute MDADI physical function; and acute-subacute FACT head/neck subscale. The 3-year local control, disease-free survival, and overall survival rates were 88%, 76%, and 82%, respectively. Conclusions We demonstrate low grade ≥3 toxicity and encouraging disease outcomes with PBT. PROs suggest significant changes in the acute-subacute period but no chronic sequelae.

Purpose: Our purpose was to use 3-dimensional (3D) surface photography to quantitatively measure breast cosmesis within the framework of a randomized clinical trial of conventionally fractionated (CF) and hypofractionated (HF) whole breast irradiation (WBI); to identify how 3D measurements are associated with patient- and physician-reported cosmesis; and to determine whether objective measures of breast symmetry varied by WBI treatment arm or transforming growth factor β 1 (TGFβ1) status. Methods and Materials: From 2011 to 2014, 287 women age ≥40 with ductal carcinoma in situ or early-stage invasive breast cancer were enrolled in a multicenter trial and randomized to HF-WBI or CF-WBI with a boost. Three-dimensional surface photography was performed at 3 years posttreatment. Patient-reported cosmetic outcomes were recorded with the Breast Cancer Treatment Outcome Scale. Physician-reported cosmetic outcomes were assessed by the Radiation Therapy Oncology Group scale. Volume ratios and 6 quantitative measures of breast symmetry, termed F1-6C, were calculated using the breast contour and fiducial points assessed on 3D surface images. Associations between all metrics, patient- and physician-reported cosmesis, treatment arm, and TGFβ1 genotype were performed using the Kruskal-Wallis test and multivariable logistic regression models. Results: Among 77 (39 CF-WBI and 38 HF-WBI) evaluable patients, both patient- and physician-reported cosmetic outcomes were significantly associated with the F1C vertical symmetry measure (both P < .05). Higher dichotomized F1C and volumetric symmetry measures were associated with improved patient- and physician-reported cosmesis on multivariable logistic regression (both P ≤ .05). There were no statistically significant differences in vertical symmetry or volume measures between treatment arms. Increased F6C horizontal symmetry was observed in the CF-WBI arm (P = .05). Patients with the TGFβ1 C-509T variant allele had lower F2C vertical symmetry measures (P = .02). Conclusions: Quantitative 3D image-derived measures revealed comparable cosmetic outcomes with HF-WBI compared with CF-WBI. Our findings suggest that 3D surface imaging may be a more sensitive method for measuring subtle cosmetic changes than global patient- or physician-reported assessments.

PurposeIn order to accurately accumulate delivered dose for head and neck cancer patients treated with the Adapt to Position workflow on the 1.5T magnetic resonance imaging (MRI)-linear accelerator (MR-linac), the low-resolution T2-weighted MRIs used for daily setup must be segmented to enable reconstruction of the delivered dose at each fraction. In this study, our goal is to evaluate various autosegmentation methods for head and neck organs at risk (OARs) on on-board setup MRIs from the MR-linac for off-line reconstruction of delivered dose.MethodsSeven OARs (parotid glands, submandibular glands, mandible, spinal cord, and brainstem) were contoured on 43 images by seven observers each. Ground truth contours were generated using a simultaneous truth and performance level estimation (STAPLE) algorithm. 20 autosegmentation methods were evaluated in ADMIRE: 1-9) atlas-based autosegmentation using a population atlas library (PAL) of 5/10/15 patients with STAPLE, patch fusion (PF), random forest (RF) for label fusion; 10-19) autosegmentation using images from a patient’s 1-4 prior fractions (individualized patient prior (IPP)) using STAPLE/PF/RF; 20) deep learning (DL) (3D ResUNet trained on 43 ground truth structure sets plus 45 contoured by one observer). Execution time was measured for each method. Autosegmented structures were compared to ground truth structures using the Dice similarity coefficient, mean surface distance, Hausdorff distance, and Jaccard index. For each metric and OAR, performance was compared to the inter-observer variability using Dunn’s test with control. Methods were compared pairwise using the Steel-Dwass test for each metric pooled across all OARs. Further dosimetric analysis was performed on three high-performing autosegmentation methods (DL, IPP with RF and 4 fractions (IPP_RF_4), IPP with 1 fraction (IPP_1)), and one low-performing (PAL with STAPLE and 5 atlases (PAL_ST_5)). For five patients, delivered doses from clinical plans were recalculated on setup images with ground truth and autosegmented structure sets. Differences in maximum and mean dose to each structure between the ground truth and autosegmented structures were calculated and correlated with geometric metrics.ResultsDL and IPP methods performed best overall, all significantly outperforming inter-observer variability and with no significant difference between methods in pairwise comparison. PAL methods performed worst overall; most were not significantly different from the inter-observer variability or from each other. DL was the fastest method (33 seconds per case) and PAL methods the slowest (3.7 – 13.8 minutes per case). Execution time increased with number of prior fractions/atlases for IPP and PAL. For DL, IPP_1, and IPP_RF_4, the majority (95%) of dose differences were within ±250 cGy from ground truth, but outlier differences up to 785 cGy occurred. Dose differences were much higher for PAL_ST_5, with outlier differences up to 1920 cGy. Dose differences showed weak but significant correlations with all geometric metrics (R2 between 0.030 and 0.314).ConclusionsThe autosegmentation methods offering the best combination of performance and execution time are DL and IPP_1. Dose reconstruction on on-board T2-weighted MRIs is feasible with autosegmented structures with minimal dosimetric variation from ground truth, but contours should be visually inspected prior to dose reconstruction in an end-to-end dose accumulation workflow.

Recurrent or previously irradiated head and neck cancers (HNC) are therapeutically challenging and may benefit from high-dose, highly accurate radiation techniques, such as stereotactic ablative radiation therapy (SABR). Here, we compare set-up and positioning accuracy across HNC subsites to further optimize the treatment process and planning target volume (PTV) margin recommendations for head and neck SABR.We prospectively collected data on 405 treatment fractions across 79 patients treated with SABR for recurrent/previously irradiated HNC. First, interfractional error was determined by comparing ExacTrac x-ray to the treatment plan. Patients were then shifted and residual error was measured with repeat x-ray. Next, cone beam computed tomography (CBCT) was compared with ExacTrac for positioning agreement, and final shifts were applied. Lastly, intrafractional error was measured with x-ray before each arc. Results were stratified by treatment site into skull base, neck/parotid, and mucosal.Most patients (66.7%) were treated to 45 Gy in 5 fractions (range, 21-47.5 Gy in 3-5 fractions). The initial mean ± standard deviation interfractional errors were -0.2 ± 1.4 mm (anteroposterior), 0.2 ± 1.8 mm (craniocaudal), and -0.1 ± 1.7 mm (left-right). Interfractional 3-dimensional vector error was 2.48 ± 1.44, with skull base significantly lower than other sites (2.22 vs 2.77; P = .0016). All interfractional errors were corrected to within 1.3 mm and 1.8°. CBCT agreed with ExacTrac to within 3.6 mm and 3.4°. CBCT disagreements and intrafractional errors of1 mm or1° occurred at significantly lower rates in skull base sites (CBCT: 16.4% vs 50.0% neck, 52.0% mucosal, P.0001; intrafractional: 22.0% vs 48.7% all others, P.0001). Final PTVs were 1.5 mm (skull base), 2.0 mm (neck/parotid), and 1.8 mm (mucosal).Head and neck SABR PTV margins should be optimized by target site. PTV margins of 1.5 to 2 mm may be sufficient in the skull base, whereas 2 to 2.5 mm may be necessary for neck and mucosal targets. When using ExacTrac, skull base sites show significantly fewer uncertainties throughout the treatment process, but neck/mucosal targets may require the addition of CBCT to account for positioning errors and internal organ motion.

Background and purpose To characterize local control and late toxicity in long-term survivors prospectively-treated with spine stereotactic radiosurgery (SSRS). Materials and methods From 2002 to 2011, 228 patients were prospectively-treated on protocol for metastatic disease of 261 vertebral sites. A subset of 52 patients surviving >4 years following treatment were collectively treated for 58 sites (encompassing 69 vertebrae) and underwent secondary analysis. Of all sites, 9% received prior radiation, and 16% encompassed multiple contiguous vertebrae. Radiation prescriptions were most commonly 24 Gy in 1 and 27 Gy in 3 fractions. Outcomes were evaluated via Kaplan–Meier, and associations analyzed via logistic regression. Results Median follow-up was 6.7 years (range: 49–142 months). Five-year local control by site was 91%, with late failures (>2 years) occurring in 3%. Overall and Grade ≥3 late toxicities (>2 years) were observed in 5% and 2% of sites. The last known neurologic event (grade 2 radiculopathy) was noted 2.1 years post-treatment, while the last documented fracture occurred at 4.1 years. No Grade ≥3 events were witnessed after 3.1 years post-SSRS, and no toxicities were noted after 4.1 years through end of follow-up. Re-irradiation, number of segments treated per site (1 vs. 2–3), and fractionation (1 vs. 3–5) were not associated with failure or toxicity. Conclusion SSRS maintains excellent disease control and a favorable late toxicity profile even among long-term survivors, with very few failures or toxicities after 2 years in this prospectively-treated population. Overall, these data support the durable control and long-term safety of SSRS with extended follow-up.

Purpose Proton therapy is increasingly prescribed for cancer treatment, given its potential for improvements in clinical outcomes and toxicity reduction; however, insurance coverage continues to be a barrier to patient access. This study examined insurance approval and appeal outcomes at a large-volume proton therapy center to clarify the process and identify areas for improvement. Methods and Materials In 2013 to 2016, 1753 patients with thoracic or head and neck cancer were considered for proton therapy; 903 (553 thoracic, 350 head and neck) entered the insurance process. Rates of and times to approval and successful appeal after initial denial were calculated. Clinical factors were evaluated for association with insurance outcomes via logistic regression. Results Approval rates by Medicare (n = 538) and private insurance (n = 365) were 91% and 30% on initial request, at a median 3 days and 14 days from inquiry to determination. Of the 306 patients initially denied coverage, 276 appealed the decision, and denial was overturned for 189 patients (68%; median time, 21 days from initial inquiry). On multivariable analysis, Medicare (odds ratio [OR], 14.20; P Conclusions Despite an 87% ultimate approval rate for proton therapy, the insurance process is a resource-intensive barrier to patient access associated with significant time delays to cancer treatment. These findings, plus the lack of clinical correlates with insurance outcomes, highlight a need for increased efficiency, transparency, and collaboration among stakeholders to promote timely patient care and research.

OBJECTIVE: To identify the optimal adjuvant treatment regimen for patients with endometrioid and non-endometrioid node-positive endometrial cancer. METHODS: We retrospectively identified 249 women with FIGO 2009 stage IIIC endometrial cancer at our institution who underwent surgical staging from 1985 to 2015 followed by external beam radiotherapy (RT), chemotherapy (CT), or a combination of CT+RT. Survival rates were calculated using the Kaplan-Meier method. RESULTS: The 5-year disease-specific survival (DSS) rate for all patients was 65%. Adjuvant CT+RT conferred higher rates of 5-year DSS as compared to CT alone in patients with grade 3 endometrioid and non-endometrioid tumors (61% vs. 27%, P = 0.04 and 67% vs. 38%, P = 0.02, respectively). Among patients with non-endometrioid tumors, treatment with concurrent chemoradiotherapy followed by additional sequential chemotherapy had higher 5-year DSS rates than with concurrent chemoradiotherapy alone (74% vs. 50%, P = 0.02). The 3-year pelvic recurrence rate was 5% with RT±CT and 35% with CT alone (P < 0.001) for all patients. No paraaortic nodal failures were observed following extended-field RT, but 14% of patients who received pelvic-only RT or CT alone developed recurrences in the paraaortic nodes (P < 0.001). CONCLUSIONS: Combined-modality therapy including adjuvant external beam pelvic radiotherapy yields excellent outcomes for patients with all subtypes of node-positive endometrial cancer. The most pronounced DSS advantage from adjuvant chemoradiotherapy was evident in women with non-endometrioid endometrial cancer.

Purpose Multigene panel testing has increased the detection of germline mutations in patients with breast cancer. The implications of using radiation therapy (RT) to treat patients with pathogenic variant (PV) mutations are not well understood and have been studied mostly in women with only BRCA1 or BRCA2 PVs. We analyzed oncologic outcomes and toxicity after adjuvant RT in a contemporary, diverse cohort of patients with breast cancer who underwent genetic panel testing. Methods and Materials We retrospectively reviewed the records of 286 women with clinical stage I-III breast cancer diagnosed from 1995 to 2017 who underwent surgery, breast or chest wall RT with or without regional nodal irradiation, multigene panel testing, and evaluation at a large cancer center's genetic screening program. We evaluated rates of overall survival, locoregional recurrence, disease-specific death, and radiation-related toxicities in 3 groups: BRCA1/2 PV carriers, non-BRCA1/2 PV carriers, and patients without PV mutations. Results PVs were detected in 25.2% of the cohort (12.6% BRCA1/2 and 12.6% non-BRCA1/2). The most commonly detected non-BRCA1/2 mutated genes were ATM, CHEK2, PALB2, CDH1, TP53, and PTEN. The median follow-up time for the entire cohort was 4.4 years (95% confidence interval, 3.8-4.9 years). No differences were found in overall survival, locoregional recurrence, or disease-specific death between groups (P > .1 for all). Acute and late toxicities were comparable across groups. Conclusion Oncologic and toxicity outcomes after RT in women with PV germline mutations detected by multigene pane testing are similar to those in patients without detectable mutations, supporting the use of adjuvant RT as a standard of care when indicated.

Human papillomavirus (HPV) infection causes 600,000 new cancers worldwide each year. HPV-related cancers express the oncogenic proteins E6 and E7, which could serve as tumor-specific antigens. It is not known whether immunity to E6 and E7 evolves during chemoradiotherapy (CRT) or affects survival. We used functional T-cell assays to identify candidate HPV-specific T-cells and T- cell motifs common across 86 patients with HPV-related cancers. These HPV-specific clones and E7-related motifs expanded over the course of treatment, whereas non-HPV-specific T-cells did not. In HPV16+ patients, improved recurrence-free survival was associated with this HPV-responsive T-cell expansion during CRT.

Postoperative radiation therapy (PORT) for non-small-cell lung cancer remains controversial with studies showing no overall survival (OS) benefit in the setting of excessive cardiopulmonary toxicity. Proton beam therapy (PBT) can potentially reduce toxicity with improved organ-at-risk sparing. We evaluated outcomes of PORT patients treated with PBT and intensity-modulated radiation therapy (IMRT).This is a retrospective review of 136 PORT patients (61 PBT, 75 IMRT) treated from 2003 to 2016. A Kaplan-Meier analysis was performed to assess oncologic outcomes. A Cox regression was conducted to identify associated factors. Total toxicity burden (TTB) was defined as grade ≥ 2 pneumonitis, cardiac, or esophageal toxicity.Median OS was 76 and 46 months for PBT and IMRT with corresponding 1- and 5-year OS of 85.3%, 50.9% and 89.3%, 37.2% (P = .38), respectively. V30 Gy heart (odds ratio [OR], 144.9; 95% confidence interval [CI], 2.91-7214; P = .013) and V5 Gy lung (OR, 15.8; 95% CI, 1.22-202.7; P = .03) were predictive of OS. Organ-at-risk sparing was improved with PBT versus IMRT; mean heart 2.0 versus 7.4 Gy (P.01), V30 Gy heart 2.6% versus 10.7% (P.01), mean lung 7.9 versus 10.4 Gy (P = .042), V5 Gy lung 23.4% versus 42.1% (P.01), and V10 Gy lung 20.4% versus 29.6% (P.01). TTB was reduced with PBT (OR, 0.35; 95% CI, 0.15-0.83; P = .017). Rates of cardiac toxicity were 14.7% IMRT and 4.9% PBT (P = .09). Rates of ≥ grade 2 pneumonitis were 17.0% IMRT and 4.9% PBT (P = .104).PBT improved cardiac and lung sparing and reduced toxicity compared with IMRT. Considering the impact of cardiopulmonary toxicity on PORT outcomes, PBT warrants prospective evaluation.

Diversity of the gut microbiome is associated with higher response rates for cancer patients receiving immunotherapy but has not been investigated in patients receiving radiation therapy. Additionally, current studies investigating the gut microbiome and outcomes in cancer patients may not have adjusted for established risk factors. Here, we sought to determine if diversity and composition of the gut microbiome was independently associated with survival in cervical cancer patients receiving chemoradiation. Our study demonstrates that the diversity of gut microbiota is associated with a favorable response to chemoradiation. Additionally, compositional variation among patients correlated with short term and long-term survival. Short term survivor fecal samples were significantly enriched in Porphyromonas, Porphyromonadaceae, and Dialister, whereas long term survivor samples were significantly enriched in Escherichia Shigella, Enterobacteriaceae, and Enterobacteriales. Moreover, analysis of immune cells from cervical tumor brush samples by flow cytometry revealed that patients with a high microbiome diversity had increased tumor infiltration of CD4+ lymphocytes as well as activated subsets of CD4 cells expressing ki67+ and CD69+ over the course of radiation therapy. Modulation of the gut microbiota before chemoradiation might provide an alternative way to enhance treatment efficacy and improve treatment outcomes in cervical cancer patients., Travis Sims and Molly El Alam et al. show that diversity of gut microbiota is associated with a favorable response to chemoradiation for cervical cancer and use flow cytometry to show that patients with high microbiome diversity had increased tumor infiltration of CD4+ lymphocytes as well as activated subsets of CD4 cells expressing ki67+ and CD69+ throughout radiation therapy. These results reveal how modulation of the gut microbiota could potentially be used to improve treatment efficacy and outcome.

Background To examine the effect of radiotherapy field size on survival outcomes and patterns of recurrence in patients treated with postoperative radiotherapy (PORT) for non-small cell lung cancer (NSCLC). Methods We retrospectively reviewed the records of 216 patients with T1-4 N1-2 NSCLC following surgery and PORT using whole mediastinum (WM) or high-risk (HR) nodal fields from 1998 to 2015. Survival rates were calculated using the Kaplan-Meier method. Univariate and multivariable analyses were conducted using Cox proportional hazards modeling for outcomes and logistic regression analysis for treatment toxicities. Results Median follow-up was 28 months (interquartile range [IQR] 13-75 months) and 38 months (IQR 19-73 months) for WM (n=131) and HR (n=84) groups, respectively. Overall survival (OS) was not significantly different between groups (median OS: HR 49 vs. WM 32 months; P=0.08). There was no difference in progression-free survival (PFS), freedom from locoregional recurrence (LRR), or freedom from distant metastasis (P>0.2 for all). Field size was not associated with OS, PFS, or LRR (P>0.40 for all). LRR rates were 20% for HR and 26% for WM groups (P=0.30). There was no significant difference in patterns of initial site of LRR between groups (P>0.1). WM fields (OR 3.73, P=0.001) and concurrent chemotherapy (OR 3.62, P=0.001) were associated with grade ≥2 toxicity. Conclusions Locoregional control and survival rates were similar between PORT groups; an improved toxicity profile was observed in the HR group. Results from an ongoing prospective randomized clinical trial will provide further insight into the consequences of high-risk PORT fields.

ObjectiveThe aim of this study was to validate a whole exome sequencing approach to longitudinally characterize the tumor mutational profile of cervical cancer patients undergoing chemoradiation (CRT).Experimental DesignCervical cancer tumor specimens from twenty-seven patients undergoing chemoradiation were collected before and throughout CRT and whole exome sequencing (WES) was performed to characterize individual mutations and alterations in unique genes. WES data were analyzed from cervical cancer patients in The Cancer Genome Atlas (TCGA) as a comparison group.ResultsOver 93% of mutated genes detected at baseline were present in TCGA. Tumor purity from collected swabs correlated with MRI tumor volumes during the course of treatment (R2=0.969). CDK4/CDK6/cyclin D1-related gene mutations involved in the ERK1/2, p16INK4, and p53 pathway and G1/S checkpoint most commonly persisted at the end of CRT.ConclusionThis non-invasive swab technique to serially sample tumor during CRT will allow new discoveries of dynamic tumor mutational profile changes during chemoradiation for mucosal tumors. Mutations that survived or increased during the initial weeks of radiation treatment are potential drivers of radiation resistance including the CDL4/CDK6/cyclin D1-related pathway.Statement of Translational RelevanceThere are no established biomarkers to predict chemoradiation (CRT) response for cervical cancer patients. Serial biopsies cannot be performed due to risks of bleeding and fistula. We used a novel non-invasive swab-based biopsy technique to obtain serial samples from a cohort of twenty-seven patients through the course of treatment, and validated this approach to obtain whole exome sequencing data. We analyzed dynamic tumor mutation profiles during CRT. Results from this study show that mutations in CDK4/CDK6/cyclin D1-related genes increased at the end of CRT, suggesting this pathway as a potential driver of radiation resistance.

Purpose: Despite aggressive primary treatment, up to 13.5% of patients diagnosed with pheochromocytoma may develop metastases, most often affecting the axial skeleton. Given that systemic therapy options are often inadequate, local therapy remains the cornerstone of palliation for these patients. Historically poor responses to standard fractionated radiotherapy have led to the consideration of stereotactic radiosurgery as an option to overcome potential radioresistance and provide durable local control of these tumors. Here we report our institutional experience in treating spine metastases from pheochromocytoma with spine stereotactic radiosurgery (SSRS). Methods and materials: Our clinical databases were retrospectively reviewed for patients with metastatic pheochromocytoma treated with SSRS from 2000-2017. Seven patients with 16 treated metastatic spinal lesions were identified. Local control was evaluated using magnetic resonance imaging (MRI). Pain and symptom data were assessed to evaluate toxicity using Common Terminology Criteria for Adverse Events (CTCAE) v4.03. The Kaplan-Meier method was used to assess local control and overall survival (OS). Results: Median follow-up for treated lesions was 11 months (range 2.2 - 70.8). Most lesions were treated to a dose of 27 Gy in three fractions (62.5%). Other fractionation schemes included 24 Gy in one fraction (25%), 16 Gy in one fraction (6.3%), and 18 Gy in three fractions (6.3%). Treatment sites included the cervical spine (18.8%), thoracic spine (37.5%), lumbar spine (31.3%), and sacrum (12.5%). The crude local control rate was 93.7%, with one thoracic spine lesion progressing 20.7 months after treatment with 24 Gy in one fraction. Kaplan-Meier OS rates at 1 and 2 years after SSRS were 71.4% and 42.9%, respectively. Most common toxicities included acute grade 1-2 pain and fatigue. There was one case of vertebral fracture in a cervical spine lesion treated to 27 Gy in three fractions, which was managed non-surgically. Conclusion: Very few studies have explored the use of SSRS in metastatic pheochromocytoma. Our data suggest this modern radiation modality is effective, safe, and provides durable local control to palliate symptoms and potentially limit further metastatic seeding. Larger patient numbers and longer follow-up will further define the role of SSRS as a treatment option in these patients.

OBJECTIVE: It has been postulated that treatment outcomes are similar between transoral robotic surgery (TORS) and definitive chemoradiation (CRT) for oropharyngeal squamous cell carcinomas (OPSCC). We compared oncologic and quality of life (QOL) outcomes between definitive CRT and definitive TORS. MATERIALS AND METHODS: An observational comparison study was performed on 92 patients treated with TORS ± adjuvant therapy and 46 patients treated with definitive CRT between July 2005 and January 2016. The Kaplan Meier method was used for survival analyses, and the Mann-Whitney test was used to compare QOL scores between groups. RESULTS: All patients had T0-T2 and N0-N2 disease, although CRT patients had higher clinical staging (p < 0.001). HPV+ disease was present in 79% (n = 73) of TORS patients and 91% (n = 19) of tested CRT patients. Median follow-up was 22.1 months (range: 0.33–83.4). There were no significant differences in locoregional control or overall survival between CRT and TORS groups. Definitive TORS resulted in better saliva-related QOL than definitive CRT at 1, 6, 12, and 24 months (p < 0.001, p = 0.025, p = 0.017, p = 0.011). Among TORS patients, adjuvant therapy was associated with worse QOL in the saliva domain at 6, 12, and 24 months (p < 0.001, p < 0.001, p = 0.007), and taste domain at 6 and 12 months (p = 0.067, p = 0.008). CONCLUSION: Definitive CRT and definitive TORS offer similar rates of locoregional control, overall survival, and disease-free survival in patients with early stage OPSCC. TORS resulted in significantly better short and long-term saliva-related QOL, whereas adjuvant therapy was associated with worse saliva and taste-related QOL compared to TORS alone.

6036 Background: Diversity of the gut microbiome is associated with response rates for patients receiving immunotherapy. Studies investigating the gut microbiome and outcomes in cancer patients often do not adjust for confounding patient and tumor characteristics. We sought to identify independent gut microbial risk factors in cervical cancer (CC) patients receiving chemoradiation (CRT) and to evaluate their impact on survival. Methods: We analyzed baseline 16S rDNA fecal microbiomes of CC patients receiving standard CRT. Patient and tumor characteristics were analyzed by univariate and multivariate Cox regression models for Recurrence-free survival (RFS) and Overall survival (OS) based on univariate p-value>0.2. Characteristics included age, body mass index (BMI), race, stage, grade, histology, nodal status, and max tumor size. Alpha (within sample) diversity was evaluated using Shannon diversity index (SDI). Kaplan-Meier curves were generated for patients with normal BMI and overweight/obese BMI based on Cox analysis. Results: 55 CC patients were included. Univariate analysis identified older age (Hazard Ratio (HR) of 0.93 (95% CI = 0.87-0.98, p = 0.0096)), SDI (HR of 0.51 (95% CI = 0.23-1.1, p = 0.087)) and BMI (HR of 0.92 (95% CI = 0.84-1, p = 0.096)) as risk factors for RFS. Multivariate survival analyses identified BMI and SDI as independent prognostic factors for RFS with a HR of 0.87 (95% CI = 0.77-0.98, p = 0.02) and 0.36 (95% CI = 0.15-0.84, p = 0.018) respectively. For OS, multivariate survival analyses again identified BMI and SDI as independent prognostic factors with a HR of 0.78 (95% CI = 0.623-0.97, p = 0.025) and 0.19 (95% CI = 0.043-0.83, p = 0.028) respectively. Conclusions: Gut diversity is a significant factor for predicting OS in CC patients undergoing CRT when BMI is accounted for, and may help explain the “obesity paradox” in cancer response. Studies exploring the relationship between gut diversity, CRT, and treatment efficacy are needed to further understand the role of the gut microbiome in treatment outcomes. [Table: see text]

The National Cancer Data Base (NCDB) was analyzed to evaluate practice patterns and the impact of radiotherapy modalities for endometrial cancer treated with primary radiotherapy.The NCDB was queried for Stage I endometrioid adenocarcinoma patients treated with primary radiotherapy without surgery from 1998 to 2006. Brachytherapy (BT) utilization factors were established using multivariable logistic regression. Log-rank and Cox proportional hazards modeling were used to assess variables impacting survival.A total of 853 patients were analyzed: 23.7%, 31.3%, and 45.0% received BT alone, external beam radiotherapy (EBRT) and BT, or EBRT alone. The BT utilization ranged from 40.5% to 51.9% over time (p=0.70). Lower utilization was associated with advanced age (≥80 years: odds ratio [OR] 0.43, 95% confidence interval [CI] 0.28-0.65, p0.01) and facilities with volume in the bottom quartile (OR 0.44, 95% CI 0.30-0.66, p0.01). Utilization was higher among patients living more than 30 miles from the facilities (OR 2.14, 95%CI 1.35-3.42, p0.01). With 36-month median followup, unadjusted median survivals for EBRT dose of 30Gy or lower, EBRT dose higher than 30Gy, BT, and EBRT+BT were 12.6, 31.1, 44.6, and 57.1 months (p0.01). After correcting for other factors, higher risk of mortality was seen with EBRT dose of 30Gy or lower (hazard ratio [HR]2.75, 95% CI 1.66-4.55, p0.01) and EBRT dose higher than 30Gy (HR 1.43, 95% CI 1.07-1.91, p=0.02) compared with EBRT+BT. No difference was seen using BT alone (HR 1.29, 95% CI 0.92-1.79, p=0.14).BT utilization for nonsurgically managed endometrial cancer remains low with most patients receiving EBRT alone. Despite concerns of overtreatment in a population with competing causes of death, BT appears to improve survival.

Preclinical evidence suggests angiotensin blockade therapy (ABT) decreases late radiation toxicities. This study aims to investigate the association between ABT and symptomatic radiation necrosis (SRN) following stereotactic radiosurgery (SRS). Resected brain metastases (rBM) and arteriovenous malformation (AVM) patients treated with SRS from 2002 to 2015 were identified. Patients in the ABT cohort were on therapy during SRS and at 1-month follow up. Kaplan Meier method and cumulative incidence model were used to analyze overall survival (OS) and intracranial outcomes. 228 consecutive patients were treated with SRS: 111 with rBM and 117 with AVM. Overall, 51 (22.4%) patients were in the ABT group: 32 (28.8%) in the rBM and 19 (16.2%) in AVM cohorts. Baseline characteristics were similar, except for higher Graded Prognostic Analysis (3–4) in the rBM (ABT: 25.0% vs. non-ABT: 49.0%, p = 0.033) and median age in the AVM (ABT: 51.4 vs. non-ABT: 35.4, p

1502 Background: Women with germline mutations in DNA repair pathways are at an increased risk of developing breast cancer. We posit that tumors arising in these patients may be more sensitive to radiotherapy and, therefore, patients may experience improved locoregional control and survival outcomes following adjuvant radiotherapy as compared to patients without DNA repair pathway mutations. Methods: We evaluated the records of 2,221 women with stage 0-III de novo primary breast cancer treated with surgery and adjuvant radiotherapy who all underwent genetic testing at our institution from 1993 to 2018. Mutations were categorized as pathogenic variant, variant of unknown significance (VUS), or negative. The Kaplan-Meier method was used to estimate the locoregional recurrence rate (LRR), rate of distant metastasis (DM), disease-free survival (DSS), and overall survival (OS) from the time of surgery. Results: The median age at diagnosis was 45 years (range 19-84). Median follow-up time was 7 years (95% confidence interval 6.6-7.4). Among 1,960 patients with evaluable radiation records, 752 (38.4%) received breast only radiation, 12 (0.6%) received chest wall only radiation, and 1,196 (61.0%) received breast/chest wall and regional nodal radiation. A total of 255 (11.4%) and 162 (7.3%) patients had a pathogenic variant mutation and a VUS only, respectively. Pathogenic variant and VUS in BRCA1/2 mutations were detected in 216 (9.7%) and 82 (3.7%) patients, respectively. Perturbations in ATM, CHEK2, MLH, MSH2/6, MUTYH, PALB2, RAD50/51, and/or TP53 were detected in 71% (85/119) of patients who tested positive for a non- BRCA1/2 pathogenic variant or VUS. On univariate analysis, there was no significant association between BRCA1/2 mutation status or any genetic mutation and rate of LRR or DM, DSS, or OS ( p > 0.10 for all). Clinicopathological features including advanced stage and lymphovascular invasion were associated with higher cumulative incidence of LRR and DM as well as shorter DFS and OS ( p < 0.01 for all). Conclusions: Herein we report on the largest cohort of women with breast cancer treated with adjuvant radiotherapy at a single institution who have undergone germline testing. Our findings suggest that the overall prognosis of breast cancer treated with adjuvant radiotherapy in patients with germline BRCA1/2 or other genetic predisposition is similar to patients with sporadic breast cancer. Further investigation to evaluate acute or late toxicities and secondary cancers as a result of radiotherapy is warranted.

Positive surgical margins after radical vulvectomy for vulvar cancer portend a high risk for local relapse, which may be challenging to salvage. We assessed the impact of adjuvant radiation therapy (aRT) on overall survival (OS) and the dose-response relationship using the National Cancer Data Base.Patients with vulvar squamous cell carcinoma who underwent initial extirpative surgery with positive margins from 1998 to 2012 were included. Factors associated with aRT and specific dose levels were analyzed using logistic regression. Log-rank and multivariable Cox proportional hazards modeling were used for OS analysis.We identified 3075 patients with a median age of 66 years (range, 22-90 years); the median follow-up time was 36.4 months (interquartile range [IQR] 15.4-71.0 months). Stage IA/B disease represented 41.2% of the cohort. Sixty-three percent underwent lymph node assessment, with a 45% positivity rate. In total, 1035 patients (35.3%) received aRT, with a median dose of 54.0 Gy (IQR 48.6-60.0 Gy). The 3-year OS improved from 58.5% to 67.4% with aRT (P.001). On multivariable analysis, age, Charlson-Deyo score ≥1, stage ≥II, tumors ≥4 cm, no aRT, and adverse nodal characteristics led to inferior survival. Dose of aRT was positively associated with OS as a continuous variable on univariate analysis (P.001). The unadjusted 3-year OS for dose subsets 30.0 to 45.0 Gy, 45.1 to 53.9 Gy, 54.0 to 59.9 Gy, and ≥60 Gy was 54.3%, 55.7%, 70.1%, and 65.3%, respectively (P.001). Multivariable analysis using a 4-month conditional landmark revealed that the greatest mortality reduction occurred in cumulative doses ≥54 Gy: 45.1 to 53.9 Gy (hazard ratio [HR] 0.94, P=.373), 54.0 to 59.9 Gy (HR 0.75, P=.024), ≥60 Gy (HR 0.71, P=.015). No survival benefit was seen with ≥60 Gy compared with 54.0 to 59.9 Gy (HR 0.95, P=.779).Patients with vulvar squamous cell carcinoma and positive surgical margins derive an OS benefit from aRT with a seemingly optimal dose in the range of 54.0 to 59.9 Gy.

Hypofractionated whole-breast irradiation (HF-WBI) remains underutilized in the United States despite support by multiple clinical trials. We evaluated the success of iterative modifications of our breast cancer clinical pathway on the adoption of HF-WBI in a large, integrated radiation oncology network.The breast clinical pathway was modified in January 2011 (Amendment 1) to recommend HF-WBI as the first option for women ≥70 of age with stages 0 to IIA, while maintaining conventional fractionation (CF) as a pathway-concordant secondary option. In January 2013 (Amendment 2), the pathway's HF-WBI recommendation was extended to women ≥50 years of age. In January 2014 (Amendment 3), the pathway mandated HF-WBI as the only pathway-concordant option in women ≥50 years of age, and all pathway-discordant plans were subject to peer review and justification. Women ≥50 years of age with ductal carcinoma in situ or invasive breast cancer who underwent breast conserving surgery and adjuvant WBI were included in this analysis.We identified 5112 patients from 2009 to 2014 who met inclusion criteria. From 2009 to 2012, the overall HF-WBI use rate was 8.3%. Following Amendments 2 and 3 (2013 and 2014, respectively), HF-WBI use significantly increased to 21.8% (17.3% in the community, 39.7% at academic sites) and 76.7% (75.5% in the community, 81.4% at academic sites), respectively (P.001). Compared to 2009 to 2012, the relative risk of using HF-WBI was 7.9 (95% confidence interval: 7.1-8.6, P.001) and 10.7 (95% CI: 10.3-11.0, P.001), respectively, after Amendments 2 and 3, respectively. Age ≥70 and treatment at an academic site increased the likelihood of receiving HF-WBI in 2009 to 2012 and following Amendment 2 (P.001).This study demonstrates the transformative effect of a clinical pathway on patterns of care for breast radiation therapy. Although our initial HF-WBI use rate was low (8%-22%) and consistent with national rates, the clinical pathway approach dramatically increased adoption rate to75%. In contrast to passive guidelines, clinical pathways serve as active tools to promote current best practices.

Purpose/Objective(s) Clinically relevant genetic predictors of radiation response for cervical cancer are understudied due to the morbidity of repeat invasive biopsies required to obtain genetic material. We have developed a novel noninvasive cervical swab technique to collect tumor DNA with adequate throughput to perform whole exome sequencing (WES) at serial timepoints over the course of chemoradiation therapy (CRT). We hypothesize that characterization of dynamic changes in the mutational landscape of cervical tumors during the course of CRT will allow for identification of molecular signatures correlating with therapy response. Materials/Methods A total of 69 patients with FIGO stage IB-IVA cervical cancer who underwent definitive CRT were prospectively enrolled on an IRB approved clinical trial. Cervical tumor DNA samples were collected by a noninvasive swab technique at baseline, and after 1, 3, and 5 weeks of CRT. Matched buccal DNA swabs were obtained to filter somatic mutations for each patient. An initial cohort included 24 patients (81 samples) and a second cohort included 45 patients (135 samples). WES was performed on the Illumina HiSeq 4000 series. Raw sequencing data were aligned to a human reference genome and MuTect was applied to detect somatic single nucleotide variants (SNV). Tumor purity (TP) was estimated from the distribution of variant allelic fractions of SNVs. In patients with pelvic MRIs at baseline and week 5 of CRT, 3D tumor volumes (TV) were generated (n = 6,8). Regression analysis was used to evaluate the goodness of fit between TP and TV. Results Estimated TP was highly correlated with TV in both cohorts (R2 = 0.969 and 0.858). Between the two cohorts, there was overlap in 4 of the top 5 genes (80%) containing the greatest number of exonic mutations across all timepoints (PIK3CA, MUC4, TPRXL, TTN). The number of altered genes present at baseline decreased over time in both cohorts. When normalized to TP, relative mutational burden decreased among standard and exceptional responders ( 20% TV remaining at week 5). The top ranked genes by magnitude of change at week 5 included MUC2, PARP10 and PIK3CA. Pathway analysis of these top ranked genes mapped to key radiation response pathways including regulation of the G1/S transition. Conclusion We validated this method of performing serial WES over the course of CRT in 2 independent prospective patient cohorts, highlighting the robustness of our novel noninvasive technique. This allowed for the identification of a panel of potential genes involved in CRT resistance. Future directions include examination of dynamic changes in copy number variation, indels, and tumor mutational burden towards a comprehensive analysis of clinically relevant drivers of CRT resistance. This may allow future targeted treatment for patients with a radioresistant genetic profile, or concurrent targeted therapy for tumors with actionable mutations.