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Purpose There remains limited data as to the feasibility, safety, and efficacy of higher doses of elective radiation therapy to the pelvic lymph nodes in men with high-risk prostate cancer. We conducted a phase II study to evaluate moderate dose escalation to the pelvic lymph nodes using a simultaneous integrated boost to the prostate. Methods and Materials Patients were eligible with biopsy-proven adenocarcinoma of the prostate, a calculated lymph node risk of at least 25%, Karnofsky performance scale ≥70, and no evidence of M1 disease. Acute and late toxicity were prospectively collected at each follow-up using Common Terminology Criteria for Adverse Events version 4.0 (CTCAE v4.0). The pelvic lymph nodes were treated to a dose of 56 Gy over 28 fractions with a simultaneous integrated boost to the prostate to a total dose of 70 Gy over 28 fractions using intensity-modulated radiation therapy. Results Thirty patients were prospectively enrolled from October 2010 to August 2014. Median patient age was 70 years (57-83), pretreatment prostate-specific antigen was 11.5 ng/mL (3.23-111.5), T stage was T2c (T1c-T3b), and Gleason score was 9 (6-9). CTCAE v4.0 rate of any grade 1 or 2 genitourinary and gastrointestinal toxicity were 55% and 44%, respectively, and there was 1 reported acute grade 3 genitourinary and gastrointestinal toxicity, both unrelated to protocol therapy. With a median follow-up of 6.4 years, the biochemical failure free survival rate was 80.2%, and mean biochemical progression free survival was 8.3 years (95% confidence interval [CI], 7.2-9.4). The prostate cancer specific survival was 95.2%, and mean prostate cancer specific survival was 8.7 years (95% CI, 8.0-9.4). Five-year distant metastases free survival was 96%. Medians were not reached. Conclusions In this single arm, small, prospective feasibility study, nodal radiation therapy dose escalation was safe, feasible, and seemingly well tolerated. Rates of progression free survival are highly encouraging in this population of predominately National Comprehensive Cancer Network very high-risk patients.

Background: The study of oligometastatic esophageal cancer (EC) is relatively new. Preliminary data suggests that more aggressive treatment regimens in select patients may improve survival rates in oligometastatic EC. However, the consensus recommends palliative treatment. We hypothesized that oligometastatic esophageal cancer patients treated with a definitive approach (chemoradiotherapy [CRT]) would have improved overall survival (OS) compared to those treated with a purely palliative intent and historical controls. Methods: Patients diagnosed with synchronous oligometastatic (any histology, ≤5 metastatic foci) esophageal cancer treated in a single academic hospital were retrospectively analyzed and divided into definitive and palliative treatment groups. Definitive CRT was defined as radiation therapy to the primary site with ≥40 Gy and ≥2 cycles of chemotherapy. Results: Of 78 Stage IVB (AJCC 8th ed.) patients, 36 met the pre-specified oligometastatic definition. Of these, 19 received definitive CRT, and 17 received palliative treatment. With a median follow-up of 16.5 months (Range: 2.3–95.0 months), median OS for definitive CRT and palliative groups were 90.2 and 8.1 months (p < 0.01), translating into 5-year OS of 50.5% (95%CI: 32.0–79.8%) vs. 7.5% (95%CI: 1.7–48.9%), respectively. Conclusions: Oligometastatic EC patients treated with definitive CRT benefited from that approach with survival rates (50.5%) that vastly exceeded historical standards of 5% at 5 years for metastatic EC. Oligometastatic EC patients treated with definitive CRT had significantly improved OS compared to those treated with palliative-only intent within our cohort. Notably, definitively treated patients were generally younger and with better performance status versus those palliatively treated. Further prospective evaluation of definitive CRT for oligometastatic EC is warranted.

The Society for Palliative Radiation Oncology (SPRO) is an international professional group dedicated to advancing the field of palliative radiation oncology by promoting evidence-based palliative radiotherapy and excellence in primary palliative care through research, education, collaboration, and patient advocacy. SPRO held its 6th Annual Meeting in Chicago, IL, USA on September 15th, 2019. The goals from SPRO's 5th Annual Meeting and progress towards those goals were reviewed, new research and educational opportunities were discussed, short- and long-term goals for the Society were detailed, and research and lifetime achievement awards were bestowed. This Meeting Report summarizes the proceedings of the 6th Annual Meeting and described future directions for SPRO.

The Society for Palliative Radiation Oncology (SPRO) is an international group of clinicians whose primary aim is to advance the field of palliative radiation oncology by promoting evidence-based palliative radiation therapy and excellence in primary palliative care through research, education, collaboration, and patient advocacy. SPRO held its 8th Annual Meeting on November 4th, 2021 in association with the American Society for Radiation Oncology (ASTRO) 63rd Annual Meeting. Accomplishments and goals from the prior year, including SPRO gaining official non-profit status, were discussed. Dr. Dirk Rades from University of Lubeck in Germany gave the keynote address, reviewing critical trials on spinal cord compression and encouraging collaboration on future trials. Recipients of the Lifetime Service Award and the Rising Star Award were announced and presented. This Meeting Report summarizes the proceedings of SPRO's 8th Annual Meeting.

Objectives Preoperative radiation therapy (RT) followed by wide-local excision with or without chemotherapy is widely accepted as management for soft tissue sarcomas (STS). Although studies have demonstrated excellent local control with this technique, there can be significant morbidity with the development of wound complications. It has been shown that sarcoma resections performed at a high-volume center lead to improved survival and functional outcomes. It is unclear, however, if radiation performed in a high-volume center leads to improved outcomes especially related to morbidity. The goal of this study was to determine whether preoperative RT performed at an academic cancer center have lower rates of wound complication compared with RT performed in community cancer centers. Materials and methods A total of 204 patients with STS were treated with preoperative RT±chemotherapy followed by limb-sparing resection. Of these, 150 patients had preoperative RT performed at an academic sarcoma center. wound complication were defined as those requiring secondary operations or prolonged wound care for 4 months following surgery. Predictors for wound complication were evaluated using a Fisher exact test for univariate analysis and logistic regression for multivariate analysis. Results The overall incidence of wound complication was 28.3%. Significant predictors for wound complication include tumor location and radiation delivered at a community hospital. The postoperative incidence of wound complication was 21% when the preoperative RT was performed at an academic cancer center versus 39% when performed at a community cancer center (P=0.009). On multivariate analysis, both tumor location (P=0.0012, 95% confidence interval: 0.03-0.45, odds ratio: 0.13) and RT performed at a community cancer center (P=0.02, 95% confidence interval: 1.13-4.48, odds ratio: 2.25) remained significant in correlation with postoperative wound complication. Conclusions Preoperative RT performed at an academic cancer center led to lower rates of postoperative wound complication. This may support the recommendation that preoperative RT and resection of STS be performed at an experienced sarcoma center.

The Society for Palliative Radiation Oncology (SPRO) is an international professional group dedicated to advancing the field of palliative radiation oncology by promoting evidence-based palliative radiotherapy and excellence in primary palliative care through research, education, collaboration, and patient advocacy. SPRO held its 7th Annual Meeting on October 28, 2020 over a virtual platform in association with the American Society for Radiation Oncology (ASTRO) 62nd Annual Meeting. Short and long-term goals for the Society were detailed and the accomplishments since SPRO's 6th Annual Meeting were reviewed. New research was presented during a series of two-minute rapid fire educational sessions given by speakers selected to present in the scientific palliative care track at the ASTRO Annual Meeting. Recipients of the Lifetime Service Award and the Rising Star Award were announced and presented. This Meeting Report summarizes the proceedings of the 7th Annual Meeting and describes future directions for SPRO.

This work reports the clinical implementation of a real-time motion tracking and correction system using dynamic multileaf collimator and jaws during helical tomotherapy delivery (Synchrony on Radixact; Accuray, Inc).The first clinical Synchrony on Radixact system was recently installed and tested at our institution. Various clinical workflows, including fiducial implantation, computed tomography simulation, treatment planning, delivery quality assurance, treatment simulation, and delivery, for both fiducial-free and fiducial-based motion tracking methods were developed. Treatment planning and delivery data from initial patients, including dosimetric benefits, real-time target detection, model building, motion tracking accuracy, delivery smoothness, and extra dose from real-time radiographic imaging, were analyzed.The Synchrony on Radixact system was tested to be within its performance specifications and has been used to treat 10 lung (fiducial-free) and 5 prostate (fiducial-based) patients with cancer so far in our clinic. The success of these treatments, especially for fiducial-free tracking, depends on multiple factors, including careful selection of the patient, appropriate setting of system parameters, appropriate positioning of the patient and skin markers, and use of treatment simulation. For the lung tumor cases, difficulties in model building, due primarily to the changes of target detectability or respiration patterns, were observed, which led to important system upgrades, including the addition of a treatment delivery simulation capability. Motion tracking metrics for all treated patients were within specifications, for example, (1) delivery quality assurance passing rates95%; (2) extra dose from radiograph0.5% of the prescription dose; and (3) average Potential Diff, measured Δ, and Rigid Body were within 6.5, 2.9, and 3.9 mm, respectively.Practical workflows for the use of the first clinical motion tracking and correction system in helical tomotherapy delivery have been developed, and the system has now been successfully implemented in our clinic for treating patients with lung and prostate cancer.

Therapeutic radiation plays an important role in the management of thymoma and thymic carcinoma. These two tumor types differ substantially in their aggressiveness and prognosis. The most pressing issue in radiotherapy is which thymoma and thymic carcinoma patients need radiation. Given that these are rare cancers, few randomized trials have been published. Controversy remains regarding which patients benefit from adjuvant radiation therapy. Existing literature spans patients treated over nearly 50 years, during which time radiation therapy has evolved from rudimentary 2-dimensional based planning to conformal 3-dimensional planning to yet more conformal dose painting techniques such as intensity-modulated radiation therapy and proton therapy. If the effect of radiation is small and the natural history of a disease long, as is the case for stage I favorable histology thymoma, then differences in techniques and toxicities may have as much of an impact as whether radiation was given or not.

PURPOSE The ability to monitor intrafractional tumor motion is essential for radiation therapy of thoracic and abdominal tumors. This study aims to develop a method to track lung tumor motion using intrafractional continuous ultrasound (US) and periodic cone-beam projection images (CBPI). METHODS Time-sequenced b-mode US and CBPI data were extracted from the data acquired with the Clarity® and XVI platforms on an Elekta linac, respectively. The data were synchronized through a video capture card (VCE-PRO, IMPERX Inc.) which was triggered by the XVI system. In this way, a system was configured to allow real-time acquisition of the diaphragm position synchronized with periodic acquisition of the lung tumor position. Feasibility of the system was demonstrated by acquiring synchronized data on an in-house motion platform with embedded spheres of different materials and US images of the diaphragm on 5 volunteers of various body sizes. Finally, ultrasound b-mode images and CBPI were also acquired simultaneously from 3 lung cancer patients. RESULTS Diaphragm motion monitoring under free breathing (FB) was successful with intracostal US imaging. We observed that diaphragm visualization decreased with the increase in the body size of the volunteer. The US system was able to track the motion as small as 2 mm in the phantom. The intrafractional CBPI acquired during VMAT delivery was successfully synchronized with US acquisition in a phantom study. Collected patient data showed a significant correlation between diaphragm motion, an internal surrogate monitored by US, and the tumor motion in superior-inferior (SI) direction monitored by XVI (P ˂ 0.0001). CONCLUSIONS The feasibility of real-time lung tumor motion tracking in SI direction with continuous ultrasound and periodic CBPI was demonstrated. The real-time estimation of the target position from the two streams for lung cancer patients would enable respiration gating or tracking during SBRT.

231 Background: Both peri-operative chemotherapy and neoadjuvant chemoradiation have been shown to improve outcomes in patients (pts) with LA-GEJ CA compared to surgery alone. Rates of post-operative chemotherapy delivery remain suboptimal. Total neo-adjuvant therapy (TNT) in LA-GEJ CA - induction chemotherapy (IC) followed by concurrent chemoradiation (CRT) - may improve systematic delivery of neoadjuvant therapy and result in favorable clinical outcomes. Methods: We retrospectively reviewed medical records of 135 pts with LA-GEJ CA at our institution between 2/2007 and 11/2019; pertinent clinical data were abstracted with Institutional Review Board approval. Patients treated with IC and curative-intent CRT with ≥40 Gy dose of radiation for adenocarcinoma were included in this analysis (N = 59). Doublet or triplet IC regimens utilizing 5-Flurouracil(5-FU), Cisplatin/Oxaliplatin and Docetaxel were commonly administered while combinations of Carboplatin +Paclitaxel or 5-FU + Oxaliplatin were used in CRT. Clinical complete response (CCR) was defined as metabolic imaging and endoscopic biopsies negative for residual malignancy after completion of TNT. Patients were followed from diagnosis to recurrence and overall survival. Survival probabilities were estimated using the Kaplan-Meier method and compared between groups using a log-rank test. Results: Out of 59 evaluable pts, 69% were clinical stage T3, 71% were node positive. 37 pts (63%) underwent surgery, R0 resection rate was 89% (33/37), pathologic complete response (pCR) rate was 19% (7/37). Among the pts who did not undergo surgery, 41% (9/22) opted to forego surgery since they attained a CCR. For the entire cohort, median Disease-Free Survival (mDFS), median Overall Survival (mOS), and 3-yr OS were 2.4 yrs, 4.7 yrs, and 67% respectively. Pts who did not undergo surgery had a mDFS, mOS, and 3-yr OS of 1.5 yrs, 4.2 yrs, and 59% respectively. Median DFS, mOS, and 3-yr OS of patients who underwent surgery were 3.5 yrs, 5.8 yrs and 72% respectively. Patients who achieved a CCR and opted to forego surgery (N = 9) had a 3 -yr DFS of 42% vs 83% for pts (N = 7) who demonstrated a pCR after curative intent tri-modality therapy. (P = 0.0099) Interestingly, the same group that achieved CCR and opted out of surgery had 3yr OS of 89% vs 83% of those who demonstrated a pCR (p = 0.0042). Conclusions: TNT for pts with LA-GEJ CA is associated with high rates of R0 resection as well as excellent DFS and OS compared to historical controls, warranting prospective evaluation. The remarkable DFS and OS in patients who opted to forego surgery due to achieving CCR is reflective of the local and systemic control rendered by this approach. Careful characterization and close longitudinal follow-up of patients who achieve CCR may help identify a subgroup of LA-GEJ CA pts who may benefit from surgery sparing approaches.

Pre-operative radiotherapy (RT) followed by limb-sparing resection is commonly used to treat soft tissue sarcomas (STS) of the extremity and chest-wall; however, this is associated with an increased risk of post-operative wound complications (WCs) compared to adjuvant RT. The use of intensity-modulated radiotherapy (IMRT) in STS has been investigated; however, the impact on WC is sparsely reported. In this study, we assess the rates of WC in patients who underwent pre-operative 3D conformal RT (3D CRT) versus IMRT followed by surgery for STS. From 2000 to 2012, 196 patients with localized STS were treated with RT +/− chemotherapy followed by resection. Patient, treatment variables, and outcomes were reviewed. Predictors for WC were evaluated using Fisher’s exact test for univariate analysis (UVA) and logistic regression for multivariate analysis (MVA). Median follow-up was 3.5 years. Of patients, 33.7 % were treated with IMRT and 66.3 % were treated with 3D CRT. Of patients, 28.6 % developed post-operative WCs. Eighteen percent of patients developed WCs when treated with IMRT versus 33 % who received 3D CRT (p = 0.03). In lower extremity tumors only, 20 % of patients that received IMRT and 43 % of patients that received 3D CRT patients had WC (p = 0.01). On MVA, both upper extremity STS (p = 0.0005, OR 0.14) and IMRT (p = 0.02, OR 0.40) predicted for a decreased propensity for post-operative WC. IMRT was associated with a significantly decreased risk of post-operative WCs compared to patients who received 3D CRT for their STS. Further studies and a larger sample size are needed to corroborate these findings.

The management of bone metastases is a multidisciplinary effort. External beam radiotherapy (EBRT) remains an effective and efficient method by which to palliate pain and prevent pathologic fracture. Various regimens have been utilized in the treatment of bone metastasis. The most commonly used and guideline-supported regimens range from 8 Gy in a single fraction to 30 Gy in 10 fractions. These regimens provide equivalent pain relief with minimal side effects. Stereotactic body radiation therapy (SBRT), a form of high-dose, highly conformal radiation therapy, shows promise in the treatment of selected patients. Due to the expense and complexity, the most appropriate indications for this technology are yet to be determined through continued accrual to ongoing clinical trials. National guidelines and quality metrics help define the use of EBRT in the treatment of uncomplicated bone metastasis.

The palliation of symptoms caused by advanced cancer is one of the most common indications for radiation therapy. Radiation therapy is an efficient and effective treatment for the palliation of pain, bleeding, obstruction, compression of nerves or the spinal cord and other local symptoms caused by tumors. The general principles of palliative radiation therapy are to use the shortest course of palliative radiation therapy needed to achieve the desired goal. It can typically be effective in a convenient single treatment (fraction) or over a small number of fractions. Given aging populations and the incidence of advanced cancer, there is increasing need for palliative radiation therapy. Many radiation oncology centers now recognize the unique needs of patients with advanced cancer and have developed palliative radiation oncology programs. This review will highlight key features of these palliative radiation oncology programs and their success in facilitating the treatment of these patients.

As palliative care (PC) moves upstream in the course of advanced illness, it is critical that PC providers have a broad understanding of curative and palliative treatments for serious diseases. Possessing a working knowledge of radiation therapy (RT), one of the three pillars of cancer care, is crucial to PC providers given RT's role in both the curative and palliative settings. This article provides PC providers with a primer on the vocabulary of RT; the team of people involved in the planning of RT; and common indications, benefits, and side effects of treatment.

Introduction NRG Oncology RTOG 0937 is a randomized phase II trial evaluating 1-year overall survival (OS) with prophylactic cranial irradiation (PCI) or PCI plus consolidative radiation therapy (PCI+cRT) to intrathoracic disease and extracranial metastases for extensive-disease SCLC. Methods Patients with one to four extracranial metastases were eligible after a complete response or partial response to chemotherapy. Randomization was to PCI or PCI+cRT to the thorax and metastases. Original stratification included partial response versus complete response after chemotherapy and one versus two to four metastases; age younger than 65 years versus 65 years or older was added after an observed imbalance. PCI consisted of 25 Gy in 10 fractions. cRT consisted of 45 Gy in 15 fractions. To detect an improvement in OS from 30% to 45% with a 34% hazard reduction (hazard ratio = 0.66) under a 0.1 type 1 error (one sided) and 80% power, 154 patients were required. Results A total of 97 patients were randomized between March 2010 and February 2015. Eleven patients were ineligible (nine in the PCI group and two in the PCI+cRT group), leaving 42 randomized to receive PCI and 44 to receive PCI+cRT. At planned interim analysis, the study crossed the futility boundary for OS and was closed before meeting the accrual target. Median follow-up was 9 months. The 1-year OS was not different between the groups: 60.1% (95% confidence interval [CI]: 41.2–74.7) for PCI and 50.8% (95% CI: 34.0–65.3) for PCI+cRT ( p = 0.21). The 3- and 12-month rates of progression were 53.3% and 79.6% for PCI and 14.5% and 75% for PCI+cRT, respectively. Time to progression favored PCI+cRT (hazard ratio = 0.53, 95% CI: 0.32–0.87, p = 0.01). One patient in each arm had grade 4 therapy-related toxicity and one had grade 5 therapy-related pneumonitis with PCI+cRT. Conclusions OS exceeded predictions for both arms. cRT delayed progression but did not improve 1-year OS.

Bleeding is a common problem in cancer patients, related to local tumor invasion, tumor angiogenesis, systemic effects of the cancer, or anti-cancer treatments. Existing bleeds can also be exacerbated by medications such as bevacizumab, nonsteroidal anti-inflammatory drugs (NSAIDs), and anticoagulants. Patients may develop acute catastrophic bleeding, episodic major bleeding, or low-volume oozing. Bleeding may present as bruising, petechiae, epistaxis, hemoptysis, hematemesis, hematochezia, melena, hematuria, or vaginal bleeding. Therapeutic intervention for bleeding should start by establishing goals of care, and treatment choice should be guided by life expectancy and quality of life. Careful thought should be given to discontinuation of medications and reversal of anticoagulation. Interventions to stop or slow bleeding may include systemic agents or transfusion of blood products. Noninvasive local treatment options include applied pressure, dressings, packing, and radiation therapy. Invasive local treatments include percutaneous embolization, endoscopic procedures, and surgical treatment.

Purpose MRI-based treatment planning in radiation therapy (RT) is prohibitive, in part, due to the lack of electron density (ED) information within the image. The dosimetric differences between MRI- and CT-based planning for intensity modulated RT (IMRT) of lung cancer were investigated to assess the appropriateness of bulk ED assignment. Methods Planning CTs acquired for six representative lung cancer patients were used to generate bulk ED IMRT plans. To avoid the effect of anatomic differences between CT and MRI, “simulated MRI-based plans” were generated by forcing the relative ED (rED) to water on CT-delineated structures using organ specific values from the ICRU Report 46 and using the mean rED value of the internal target volume (ITV) from the planning CT. The “simulated MRI-based plans” were generated using a research planning system (Monaco v5.09.07a, Elekta, AB) and employing Monte Carlo dose calculation. The following dose-volume-parameters (DVPs) were collected from both the “simulated MRI-based plans” and the original planning CT: D95, the dose delivered to 95% of the ITV & planning target volume (PTV), D5 and V5, the volume of normal lung irradiated > 5 Gy. The percent point difference and relative dose difference were used for comparison with the CT based plan for V5 and D95, respectively. A total of five plans per patient were generated; three with the ITV rED (rEDITV) = 1.06, 1.0 and the mean value from the planning CT while the lung rED (rEDlung) was fixed at the ICRU value of 0.26 and two with rEDlung = 0.1 and 0.5 while the rEDITV was fixed to the mean value from the planning CT. Results Noticeable differences in the ITV and PTV DVPs were observed. Variations of the normal lung V5 can be as large as 9.6%. In some instances, varying the rEDITV between rEDmean and 1.06 resulted in D95 increases ranging from 3.9-6.3%. Bulk rED assignment on normal lung affected the DVPs of the ITV and PTV by 4.0-9.8% and 0.3-19.6%, respectively. Dose volume histograms were presented for representative cases where the variations in the DVPs were found to be very large or very small. Conclusions The commonly-used bulk rED assignment in MRI-only based planning may not be appropriate for lung cancer. A voxel based method, e.g. synthetic CT generated from MRI data, is likely required for dosimetrically accurate MR-based planning for lung cancer. This article is protected by copyright. All rights reserved.

Purpose To investigate early tumor and normal tissue responses during the course of radiation therapy (RT) for lung cancer using quantitative analysis of daily computed tomography (CT) scans. Methods and Materials Daily diagnostic-quality CT scans acquired using CT-on-rails during CT-guided RT for 20 lung cancer patients were quantitatively analyzed. On each daily CT set, the contours of the gross tumor volume (GTV) and lungs were generated and the radiation dose delivered was reconstructed. The changes in CT image intensity (Hounsfield unit [HU]) features in the GTV and the multiple normal lung tissue shells around the GTV were extracted from the daily CT scans. The associations between the changes in the mean HUs, GTV, accumulated dose during RT delivery, and patient survival rate were analyzed. Results During the RT course, radiation can induce substantial changes in the HU histogram features on the daily CT scans, with reductions in the GTV mean HUs (dH) observed in the range of 11 to 48 HU (median 30). The dH is statistically related to the accumulated GTV dose ( R 2 > 0.99) and correlates weakly with the change in GTV ( R 2 = 0.3481). Statistically significant increases in patient survival rates ( P =.038) were observed for patients with a higher dH in the GTV. In the normal lung, the 4 regions proximal to the GTV showed statistically significant ( P Conclusion Quantitative analysis of the daily CT scans indicated that the mean HUs in lung tumor and surrounding normal tissue were reduced during RT delivery. This reduction was observed in the early phase of the treatment, is patient specific, and correlated with the delivered dose. A larger HU reduction in the GTV correlated significantly with greater patient survival. The changes in daily CT features, such as the mean HU, can be used for early assessment of the radiation response during RT delivery for lung cancer.

Background Among patients with osseous metastases, breast cancer (BC) patients typically have the best prognosis. In the palliative setting, BC is often considered a single disease, but based on receptor status there are four distinct subtypes: luminal A (LA), luminal B (LB), triple negative (TN), and HER2‐enriched (HER2). We hypothesize that survival and palliative outcomes following palliative RT for osseous metastases correlate with breast cancer subtype (BCS). Methods We identified 3,895 BC patients with known receptor status who received palliative RT for osseous metastases from 2004–2013 in the National Cancer Database. Kaplan–Meier method with log‐rank testing and univariate/multivariate Cox‐regression was used to identify survival factors. Incomplete radiation courses, 30‐day mortality rate, and percentage remaining life spent receiving RT (PRLSRT) were calculated. Results Subtypes were 54% LA, 33% LB, 8% TN, and 5% HER2 with median survival of 34.1, 28.2, 5.3, and 15.7 months, respectively (p, This study demonstrates the impact of breast cancer subtype on survival and palliative outcomes after palliative radiation for osseous metastases. Patients with triple negative and HER2‐enriched subtypes had shorter survival, higher 30 and 90‐day mortality, had more incomplete treatments, spent more of their remaining lives receiving radiation treatments, but received similar radiation regimens compared to Luminal A and Luminal B patients. This correlation should be considered when selecting palliative radiotherapy regimens to avoid unnecessary treatment and improve palliative outcomes for poor‐prognosis patients.

Purpose To quantify interfractional independent motions between multiple primary targets in radiation therapy (RT) of lung cancer and to study the dosimetric benefits of an online adaptive replanning method to account for these variations. Methods and materials Ninety-five on-treatment diagnostic-quality computed tomography (CT) scans acquired for 9 lung cancer patients treated with image-guided RT (IGRT) using a CT-on-rails (CTVision, Siemens) were analyzed. On each on-treatment CT set, contours of the targets (gross tumor volume, clinical target volume, or involved nodes), and organs at risk were generated by populating the planning contours using an autosegmentation tool (ABAS, Elekta) with manual editing. For each patient, an intensity modulated RT plan was generated based on the planning CT with a prescription dose of 60 Gy in 2 Gy per fraction. Three plans were generated and compared for each on-treatment CT set: an IGRT (repositioning) plan by copying the original plan with the required shifts, an online adaptive plan by rapidly modifying the aperture shapes, and segment weights of the original plan to conform to the on-treatment anatomy and a new fully reoptimized plan based on the on-treatment CT. Results The interfractional deviations of the distance between centers of masses of the targets from the planning CTs varied from –1.0 to 0.8 cm with an average –0.09 ± 0.41 cm (1 standard deviation). The average combined CTV receiving at least 100% of the prescribed dose (V100) were 99.0 ± 0.7%, 97.8 ± 2.8%, 99.0 ± 0.6%, and 99.1 ± 0.6%, and the lung V 20Gy 928 ± 332 cm 3 , 944 ± 315 cm 3 , 917 ± 300 cm 3 , and 891 ± 295 cm 3 for the original, repositioning, adaptive, and reoptimized plans, respectively. Wilcoxon signed-rank tests showed that the adaptive plans were statistically significantly better than the repositioning plans and comparable with the reoptimized plans. Conclusion Interfractional, relative volume changes and independent motions between multiple primary targets during lung cancer RT, which cannot be accounted for by the current IGRT repositioning exist, but can be corrected by the online adaptive replanning method.

242 Background: Stereotactic body radiation therapy (SBRT) is an emerging modality of treatment designed to deliver high radiation doses in few fractions. We examine practice trends in the use of SBRT for managing bone metastases in patients with breast, kidney, non-small-cell lung, melanoma, or prostate cancer. Methods: We selected patients from the National Cancer Database (2004-2013) diagnosed with bone metastases from breast, kidney, non-small-cell lung, melanoma, or prostate cancer. SBRT fractionation regimens were defined as 12-45 Gy in 1 fraction, 14-50 Gy in 2 fractions, 21-50 Gy in 3 fractions, 28-50 Gy in 4 fractions, and 30-60 Gy in 5 fractions. Standard palliative radiation fractionation regimens were defined as all other cases with 2-40 Gy in 20 fractions or fewer. Results: Patients receiving SBRT regimens made up 1454 of 57,556 total palliative cases. Bone metastases treated with SBRT primarily at the spine (65.5%), hip/pelvis (12.3%), and shoulder/extremity (11.4%). SBRT palliation regimens were used for only 2.5% of patients. Though standard palliative radiation fractionation regimens comprised the majority of treatments (97.5%), SBRT utilization is increasing, with a majority (68.4%) of SBRT cases occurring from 2009-2013. Treatment at an academic center and lack of comorbidities were positively associated with receiving SBRT regimens. Mean survival outcomes were higher for patients receiving SBRT (24.3 months) than patients receiving standard regimens (16.9 months). Conclusions: Though the vast majority of bone metastases were treated with standard palliative radiation fractionation, SBRT utilization increased from 2004-2013, with the greatest portion of SBRT cases occurring at academic institutions. Patients receiving SBRT exhibit better survival outcomes, likely as a result of patient selection practices.