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Purpose: The use of respiratory gating for management of breathing motion during stereotactic body radiation therapy (SBRT) relies on a consistent relationship between the breathing signal and the actual position of the internal target. This relationship was investigated in patients treated for pancreatic cancer. Methods: Four patients with pancreatic cancer undergoing SBRT that had implanted fiducials in the tumor were included in this study. Treatment plans were generated based on the exhale phases (30–70%) from the pre-treatment 4DCT. The margin between the internal target volume (ITV) and the planning target volume was three mm. After patient setup using cone-beam CT, simultaneous fluoroscopic imaging and breathing motion monitoring were used during at least three breathing cycles to verify the fiducial position and to optimize the gating window. After treatment, fluoroscopic images were acquired for verification purposes and exported for retrospective analyses. Fiducial positions were determined using a template-matching algorithm. For each dataset, we established a linear relationship between the fiducial position and the anterior-posterior (AP) breathing signal. The relationships before and after treatment were compared and the dose distribution impact evaluated. Results: Seven pre- and post-treatment fluoroscopic pairs were available for fiducial position analyses in the superior-inferior (SI) and left-right (LR) directions, and five in the AP direction. Time between image acquisitions was typically six to eight minutes. An average absolute change of 1.2±0.7 mm (range: 0.1–1.7) of the SI fiducial position relative to the external signal was found. Corresponding numbers for the LR and AP fiducial positions were 0.9±1.0 mm (range: 0.2–3.0) and 0.5±0.4 mm (range: 0.2–1.2), respectively. The dose distribution impact was small in both the ITV and organs-at-risk. Conclusion: The relationship change between fiducial position and external breathing signal has been observed to be about 1 mm in four pancreas SBRT patients, leading to small dose distribution impact. Pettersson and Cervino are funded by a Varian Medical Systems grant.

91 Background: Randomized trials among advanced cancer patients demonstrate that early palliative care integration into usual oncology care reduces symptom burden, improves quality of life and caregiver outcomes, and may improve survival. The impact of palliative care on health economics remains poorly defined and reported cost savings are an unintentional consequence of providing care aligned with patient goals. This study determined the impact of palliative care on healthcare costs among elderly patients with advanced cancer. Methods: We conducted a matched case-control study among Medicare beneficiaries with metastatic lung, colorectal, breast and prostate cancers. We matched patients who received a palliative care consultation to similar patients who did not receive a palliative care consultation. To determine the economic impact of a palliative care consultation we compared costs between cases and controls before and after the palliative care intervention. Costs included inpatient, outpatient, home health care, hospice, and medical equipment, and were adjusted to 2011 dollars. Results: Among the 2,576 patients in this study the total healthcare costs per patient in the 30 days before palliative care consultation was balanced between palliative care ($12,881) and non-palliative care control patients ($12,335). Palliative care intervention reduced total healthcare costs after the intervention. The total cost of care per patient in the 120 days after palliative care exposure was $6,880 compared to $9,604 for controls (28% decrease; p < 0.001). The economic effect of palliative care depended on timing of the consult. Palliative care consultation within 7 days of death decreased healthcare costs by $975, whereas palliative care consultation more than 4 weeks from death decreased costs by $5,362. Conclusions: This study demonstrates that palliative care has the capacity to substantially reduce healthcare expenditures among advanced cancer patients. Furthermore, the cost reduction depends on timing of the palliative care consult.

6026 Background: The Checkmate 141 randomized trial found that patients with platinum-refractory, recurrent or metastatic (R/M) squamous-cell carcinoma of the head and neck (SCCHN) treated with nivolumab had significantly longer overall survival than those treated with standard, single-agent therapy. However, nivolumab is more expensive than standard treatment. We conducted a cost-effectiveness analysis of nivolumab for the treatment of R/M SCCHN. Methods: We constructed a Markov model to simulate treatment with nivolumab or other single-agent therapy (docetaxel, cetuximab, or methotrexate) for patients with R/M SCCHN. Transition probabilities including disease progression, survival, and toxicity were derived from clinical trial data, while costs (in 2016 US dollars) and health utilities were estimated from the literature. Incremental cost-effectiveness ratios (ICERs), expressed as dollar per quality-adjusted life-year (QALY), were calculated with values less than $100,000/QALY considered cost-effective from a healthcare payer perspective. We conducted one-way and probabilistic sensitivity analyses to examine model uncertainty. Results: Our base-case model found that treatment with nivolumab increased overall cost by $59,000 and improved effectiveness by 0.2443 QALYs compared to single-agent therapy, leading to an ICER of $241,100/QALY. In sensitivity analyses, the model was most sensitive to the cost of nivolumab and assumptions about survival. Nivolumab would become cost-effective if the cost per cycle decreased from $13,432 to $5,716. If we assumed that all patients alive at the end of the Checkmate 141 trial were cured of their disease then nivolumab was still not considered cost-effective (ICER $160,000/QALY). Probabilistic sensitivity analysis also demonstrated relative stability of the cost-effectiveness model and found that treatment with nivolumab was cost-effective 0% of the time at a willingness-to-pay threshold of $100,000/QALY. Conclusions: While nivolumab significantly improves overall survival, at the current cost it would not be considered a cost-effective treatment option for patients with R/M SCCHN.

Importance There is a dearth of population-based evidence regarding outcomes of the adolescent and young adult (AYA) population with gastrointestinal stromal tumors (GISTs). Objectives To describe a large cohort of AYA patients with GISTs and investigate the effect of surgery on GIST-specific survival (GSS) and overall survival (OS). Design, Setting, and Participants This retrospective cohort study of 392 AYA patients and 5373 older adult (OA) patients in the Surveillance, Epidemiology, and End Results (SEER) database with GISTs histologically diagnosed from January 1, 2001, through December 31, 2013, with follow-up through December 31, 2015, compared the baseline characteristics of AYA (13-39 years old) and OA (≥40 years old) patients and among AYA patients stratified by operative management. Kaplan-Meier estimates were used for OS analyses. Cumulative incidence functions were used for GSS analysis. The effect of surgery on survival was evaluated with a multivariable Fine-Gray regression model. Exposure Tumor resection. Main Outcomes and Measures GIST-specific survival and OS. Results This study included 392 AYA and 5373 OA patients diagnosed with GISTs (207 [52.8%] male AYA patients, 2767 [51.5%] male OA patients, 277 [70.7%] white AYA patients, and 3661 [68.1%] white OA patients). Compared with the OA patients, more AYA patients had small-intestine GISTs (139 [35.5%] vs 1465 [27.3%], P = .008) and were managed operatively (332 [84.7%] vs 4212 [78.4%], P = .003). Multivariable analysis of AYA patients found that nonoperative management was associated with a more than 2-fold increased risk of death from GISTs (subdistribution hazard ratio, 2.27; 95% CI, 1.21-2.25; P = .01). On subset analysis of 349 AYA patients with tumors of the stomach and small intestine, small-intestine location was associated with improved survival (OS: 91.1% vs 77.2%, P = .01; GSS: 91.8% vs 78.0%, P = .008). On subset analysis of 91 AYA patients with metastatic disease, operative management was associated with improved survival (OS: 69.5% vs 53.7%, P = .04; GSS: 71.5% vs 56.7%, P = .03). Conclusions and Relevance This study found that AYA patients are more likely to undergo surgical management than OA patients. Operative management is associated with improved OS and GSS in AYA patients, including those with metastatic disease.

Introduction: In the U.S., approximately 25% of all breast cancer cases occur before the age of 50 years. Younger age at diagnosis of breast cancer is associated with lower survival when compared to older cases. Data on sociodemographic predictors of mortality in younger vs. older breast cancer patients are scarce. We assessed differences in risk of total mortality between women 50 years and younger vs. those >50 years, according to health insurance status, race/ethnicity, and neighborhood socioeconomic status (nSES). Methods: We used data from the population-based California Cancer Registry including invasive female breast cancer cases 18 years of age and older diagnosed between 2005 and 2012 with follow-up through December 31, 2013 and identified 145,564 women. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for total mortality for younger (≤years) and older (>50 years) patients. Multivariable models were stratified by stage, allowing baseline hazards to vary by stage, and adjusted for year of diagnosis, single year age, race/ethnicity, nSES, insurance status, tumor subtype, grade, histology, tumor size, lymph node status, as well as treatment modalities (surgery, chemotherapy, and radiation therapy). Results: Among 145,564 breast cancer cases, 3971 total deaths occurred in patients ≤50 years of age and 18,639 deaths in those >50 years. Significant interactions by age group were observed for race/ethnicity ( Conclusions: Our results show differences in total mortality associated with important sociodemographic factors comparing younger to older breast cancer patients. Specifically, higher risks of dying were observed for non-privately vs. privately insured patients and for Blacks vs. NHWs in younger compared to older women, even after accounting for clinical and other sociodemographic factors. These results suggest that access to care is possibly a more important driver in mortality outcome in younger vs. older women, and additional analyses will evaluate the extent to which treatment explains these differences. The findings are important given the higher rates of recurrence and less favorable survival in younger compared to older breast cancer patients. Citation Format: Li Tao, Scarlett Lin Gomez, Caroline Thompson, Ming-Hsiang Tsou, Joseph Gibbons, Jesse N. Nodora, Ian Komenaka, Richard Schwab, Jonathan Unkart, James Murphy, Maria Elena Martinez. Mortality Differences in Younger and Older Breast Cancer Patients according to Insurance, Race/Ethnicity, and Neighborhood Socioeconomic Status in the California Cancer Registry. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr C30.

Purpose. The inherent difficulty of identifying liver and pancreas tumors without intravenous contrast creates the need for implanted metal fiducials to visualize tumor position and motion in stereotactic body radiation therapy (SBRT). Unfortunately, the invasive procedure of implanting fiducials carries a risk of toxicity, introduces a treatment delay, and creates streak artifacts on treatment planning images, which can hinder tumor identification. A fiducial-less motion management strategy would improve the safety, tolerability, and availability of abdominal SBRT. We hypothesized that upper abdominal tumor motion would correlate with the motion of nearby organs and could thereby serve as a fiducial-less proxy for tumor motion. Methods. We retrospectively identified fifteen patients with pancreatic cancer or liver cancer treated with SBRT. The liver, superior mesenteric artery, and celiac artery were delineated on 4DCT images and used to predict tumor position. The correlation with tumor motion was quantified with Pearson correlation coefficients (r), and accuracy of the tumor position prediction was expressed as the mean absolute error. Results. The majority of motion with respiration occurred in the superior–inferior (SI) direction with an average of 6.4 mm (range 2.4–11.3 mm) for pancreatic and 13.0 mm (range 6.4–21.2 mm) for liver tumors. In the SI direction we found a tight correlation between liver and tumor motion in pancreas cancer patients (r = 0.92 ± 0.10), and liver tumor patients (r = 0.97 ± 0.02). Using the liver as surrogate, predicted tumor location was on average 0.5 mm from the actual position and not greater than 3.0 mm. Conclusions. This study demonstrates a potential correlation of normal organ and tumor motion which could serve as a fiducial-less surrogate for SBRT in the upper abdomen as on-site 4D volumetric imaging becomes available during treatment. Moving this motion management strategy into the clinic requires additional research to optimize 4D image quality and understand inter-fraction reproducibility.

Most gastrointestinal stromal tumors (GISTs) are considered nonhereditary or sporadic. However, single-institution studies suggest that GIST patients develop additional malignancies at increased frequencies. It was hypothesized that greater insight could be gained into possible associations between GISTs and other malignancies with a national cancer database inquiry.Patients diagnosed with GISTs (2001-2011) in the Surveillance, Epidemiology, and End Results database were included. Standardized prevalence ratios (SPRs) and standardized incidence ratios (SIRs) were used to quantify cancer risks incurred by GIST patients before and after GIST diagnoses, respectively, in comparison with the general US population.There were 6112 GIST patients, and 1047 (17.1%) had additional cancers. There were significant increases in overall cancer rates: 44% (SPR, 1.44) before the GIST diagnosis and 66% (SIR, 1.66) after the GIST diagnosis. Malignancies with significantly increased occurrence both before and after diagnoses included other sarcomas (SPR, 5.24; SIR, 4.02), neuroendocrine-carcinoid tumors (SPR, 3.56; SIR, 4.79), non-Hodgkin lymphoma (SPR, 1.69; SIR, 1.76), and colorectal adenocarcinoma (SPR, 1.51; SIR, 2.16). Esophageal adenocarcinoma (SPR, 12.0), bladder adenocarcinoma (SPR, 7.51), melanoma (SPR, 1.46), and prostate adenocarcinoma (SPR, 1.20) were significantly more common only before the GIST diagnosis. Ovarian carcinoma (SIR, 8.72), small intestine adenocarcinoma (SIR, 5.89), papillary thyroid cancer (SIR, 5.16), renal cell carcinoma (SIR, 4.46), hepatobiliary adenocarcinoma (SIR, 3.10), gastric adenocarcinoma (SIR, 2.70), pancreatic adenocarcinoma (SIR, 2.03), uterine adenocarcinoma (SIR, 1.96), non-small cell lung cancer (SIR, 1.74), and transitional cell carcinoma of the bladder (SIR, 1.65) were significantly more common only after the GIST diagnosis.This is the first population-based study to characterize the associations and temporal relations between GISTs and other cancers by both site and histological type. These associations may carry important clinical implications for future cancer screening and treatment strategies.

Stereotactic body radiotherapy (SBRT) shows promise in unresectable pancreatic cancer, though this treatment modality has high rates of normal tissue toxicity. This study explores the dosimetric utility of daily adaptive re-planning with pancreas SBRT. We used a previously developed supercomputing online re-planning environment (SCORE) to re-plan 10 patients with pancreas SBRT. Tumor and normal tissue contours were deformed from treatment planning computed tomographies (CTs) and transferred to daily cone-beam CT (CBCT) scans before re-optimizing each daily treatment plan. We compared the intended radiation dose, the actual radiation dose, and the optimized radiation dose for the pancreas tumor planning target volume (PTV) and the duodenum. Treatment re-optimization improved coverage of the PTV and reduced dose to the duodenum. Within the PTV, the actual hot spot (volume receiving 110% of the prescription dose) decreased from 4.5% to 0.5% after daily adaptive re-planning. Within the duodenum, the volume receiving the prescription dose decreased from 0.9% to 0.3% after re-planning. It is noteworthy that variation in the amount of air within a patient׳s stomach substantially changed dose to the PTV. Adaptive re-planning with pancreas SBRT has the ability to improve dose to the tumor and decrease dose to the nearby duodenum, thereby reducing the risk of toxicity.

To date, all population-based epidemiologic data on gastrointestinal stromal tumor (GIST) in the United States predate the 2001 implementation of GIST-specific histology coding. As such, results from previous studies were limited because of inclusion of non-GIST abdominal or gastrointestinal sarcomas. We used a national cancer registry with modern day histologic codes to gain greater insight into the true epidemiology of GIST in the United States. We identified 6,142 patients diagnosed with GIST between 2001 and 2011 in the Surveillance, Epidemiology, and End Results database. Incidence, survival, demographic risk factors, and prognostic factors were analyzed. Annual age-adjusted incidence rose from 0.55/100,000 in 2001 to 0.78/100,000 in 2011 and increased with age, peaking among 70- to 79-year-olds (3.06/100,000). GIST was also more common in males than females [rate ratio (RR), 1.35], non-Hispanics than Hispanics (RR, 1.23), and blacks (RR, 2.07) or Asians/Pacific Islanders (RR, 1.50) than whites. The study period had 5-year overall and GIST-specific survival rates of 65% and 79%, respectively. The 5-year overall survival rates for those with localized, regional, and metastatic disease at diagnosis were 77%, 64%, and 41%, respectively. Multivariate analyses demonstrated that older age at diagnosis, male sex, black race, and advanced stage at diagnosis were independent risk factors for worse overall survival. Multivariate analysis also showed the four aforementioned characteristics, along with earlier year of diagnosis, to be independent risk factors for worse GIST-specific survival. As the first population-based, epidemiologic study of histologically confirmed disease, our findings provide a robust representation of GIST in the era of immunohistochemical diagnoses. Cancer Epidemiol Biomarkers Prev; 24(1); 298–302. ©2014 AACR.

Purpose/Objectives(s) Early-stage endometrial cancer patients are at higher risk of noncancer mortality than of cancer mortality. Competing event models incorporating comorbidity could help identify women most likely to benefit from treatment intensification. Methods and Materials 67,397 women with stage I-II endometrioid adenocarcinoma after total hysterectomy diagnosed from 1988 to 2009 were identified in Surveillance, Epidemiology, and End Results (SEER) and linked SEER-Medicare databases. Using demographic and clinical information, including comorbidity, we sought to develop and validate a risk score to predict the incidence of competing mortality. Results In the validation cohort, increasing competing mortality risk score was associated with increased risk of noncancer mortality (subdistribution hazard ratio [SDHR], 1.92; 95% confidence interval [CI], 1.60-2.30) and decreased risk of endometrial cancer mortality (SDHR, 0.61; 95% CI, 0.55-0.78). Controlling for other variables, Charlson Comorbidity Index (CCI) = 1 (SDHR, 1.62; 95% CI, 1.45-1.82) and CCI >1 (SDHR, 3.31; 95% CI, 2.74-4.01) were associated with increased risk of noncancer mortality. The 10-year cumulative incidences of competing mortality within low-, medium-, and high-risk strata were 27.3% (95% CI, 25.2%-29.4%), 34.6% (95% CI, 32.5%-36.7%), and 50.3% (95% CI, 48.2%-52.6%), respectively. With increasing competing mortality risk score, we observed a significant decline in omega (ω), indicating a diminishing likelihood of benefit from treatment intensification. Conclusion Comorbidity and other factors influence the risk of competing mortality among patients with early-stage endometrial cancer. Competing event models could improve our ability to identify patients likely to benefit from treatment intensification. © 2014 Elsevier Inc.

Purpose/Objective Palliative radiation therapy represents an important treatment option among patients with advanced cancer, although research shows decreased use among older patients. This study evaluated age-related patterns of palliative radiation use among an elderly Medicare population. Methods and Materials We identified 63,221 patients with metastatic lung, breast, prostate, or colorectal cancer diagnosed between 2000 and 2007 from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Receipt of palliative radiation therapy was extracted from Medicare claims. Multivariate Poisson regression analysis determined residual age-related disparity in the receipt of palliative radiation therapy after controlling for confounding covariates including age-related differences in patient and demographic covariates, length of life, and patient preferences for aggressive cancer therapy. Results The use of radiation decreased steadily with increasing patient age. Forty-two percent of patients aged 66 to 69 received palliative radiation therapy. Rates of palliative radiation decreased to 38%, 32%, 24%, and 14% among patients aged 70 to 74, 75 to 79, 80 to 84, and over 85, respectively. Multivariate analysis found that confounding covariates attenuated these findings, although the decreased relative rate of palliative radiation therapy among the elderly remained clinically and statistically significant. On multivariate analysis, compared to patients 66 to 69 years old, those aged 70 to 74, 75 to 79, 80 to 84, and over 85 had a 7%, 15%, 25%, and 44% decreased rate of receiving palliative radiation, respectively (all P

Purpose: To assess the accuracy of internal target volume (ITV) segmentation of lung tumors for treatment planning of simultaneous integrated boost (SIB) radiotherapy as seen in 4D PET/CT images, using a novel 3D-printed phantom. Methods: The insert mimics high PET tracer uptake in the core and 50% uptake in the periphery, by using a porous design at the periphery. A lung phantom with the insert was placed on a programmable moving platform. Seven breathing waveforms of ideal and patient-specific respiratory motion patterns were fed to the platform, and 4D PET/CT scans were acquired of each of them. CT images were binned into 10 phases, and PET images were binned into 5 phases following the clinical protocol. Two scenarios were investigated for segmentation: a gate 30–70 window, and no gating. The radiation oncologist contoured the outer ITV of the porous insert with on CT images, while the internal void volume with 100% uptake was contoured on PET images for being indistinguishable from the outer volume in CT images. Segmented ITVs were compared to the expected volumes based on known target size and motion. Results: 3 ideal breathing patterns, 2 regular-breathing patient waveforms, and 2 irregular-breathing patient waveforms were used for thismore » study. 18F-FDG was used as the PET tracer. The segmented ITVs from CT closely matched the expected motion for both no gating and gate 30–70 window, with disagreement of contoured ITV with respect to the expected volume not exceeding 13%. PET contours were seen to overestimate volumes in all the cases, up to more than 40%. Conclusion: 4DPET images of a novel 3D printed phantom designed to mimic different uptake values were obtained. 4DPET contours overestimated ITV volumes in all cases, while 4DCT contours matched expected ITV volume values. Investigation of the cause and effects of the discrepancies is undergoing.« less

Purpose: Approximately one half of the radiotherapy (RT) prescribed in the United States is delivered with palliative intent. The purpose of this study was to investigate the patterns of delivery of palliative RT across the United States. Methods: Using the Surveillance, Epidemiology, and End Results-Medicare linked database, 51,610 patients were identified with incident stage IV breast, prostate, lung, or colorectal cancer diagnosed between 2000 and 2007 and observed through 2009. Multivariate logistic regression determined predictors of palliative RT. Results: Forty-one percent of the study population received palliative RT, including 53% of patients with lung cancer, followed by those with breast (42%), prostate (40%), and colorectal cancers (12%). Multivariate analysis revealed that older patients (P < .001) and those with higher Charlson comorbidity scores (P < .001) were less likely to receive palliative RT. Black patients with prostate cancer were 20% less likely (P < .001), and black patients with colorectal cancer were 28% less likely (P < .001), than white patients to receive palliative RT. Among those treated with RT, 23% of patients with lung cancer died within 2 weeks of completing treatment, followed by those with colorectal (12%), breast (11%), and prostate cancers (8%). In addition to tumor site, significant predictors (P < .05) of death within 2 weeks of receiving RT included increased age, increased comorbidity, and male sex. Conclusion: Inequality in the receipt of palliative RT exists among the elderly and patients with comorbid conditions and varies with race. In addition, a significant number of patients die shortly after receiving RT. Understanding these patterns of care, along with further research into the underlying causes, will improve access and quality of palliative RT. Copyright © 2013 by American Society of Clinical Oncology.

The purpose of this study was to present our experience utilizing cetuximab and platinum-based concurrent chemoradiotherapy for the definitive treatment of head and neck squamous cell carcinoma (HNSCC).Patients (n = 177) who received definitive concurrent chemoradiotherapy for HNSCC were stratified into 3 groups: receiving cetuximab monotherapy (n = 24), cetuximab and chemotherapy combination (n = 33), or platinum-based chemotherapy without cetuximab (n = 120). Primary endpoints were freedom from relapse, event-free survival, and overall survival (OS).Patients receiving cetuximab monotherapy were older with lower Karnofsky performance status (KPS) and higher Charlson comorbidity scores compared with those treated with combination cetuximab and chemotherapy or platinum-based concurrent chemoradiotherapy. Patients treated with platinum-based concurrent chemoradiotherapy exhibited significantly better freedom from relapse, event-free survival, and OS compared with those receiving cetuximab monotherapy or cetuximab and chemotherapy combination therapies (all p.05). Differences between patients receiving cetuximab monotherapy and platinum-based concurrent chemoradiotherapy held on multivariate Cox regression.This study suggests that platinum-based concurrent chemoradiotherapy is superior to cetuximab-based monotherapy for the definitive treatment of HNSCC.

Introduction/Background The aim of this study was to identify imaging-based predictors of progression in patients treated with SABR for stage I NSCLC. Patients and Methods Between March 2003 and December 2012, 117 patients with stage I NSCLC meeting our study criteria were treated with SABR at Stanford University. Median follow-up was 17 months (range, 3-74 months) for all patients and 19 months for living patients (range, 3-74 months). Tumors were classified according to whether or not they contacted the pleura adjacent to the chest wall or mediastinum (MP), according to their maximum dimension based on computed tomography scans, and, for 102 patients who had archived pretreatment fluorine-18 fluorodeoxyglucose positron-emission tomography scans, according to SUVmax. Results Ten patients (9%) developed local progression, 17 (15%) developed regional progression, and 19 (16%) developed distant metastasis. Two-year freedom from local progression, freedom from regional progression, and freedom from distant metastasis (FFDM) were 88%, 83%, and 83%, respectively. Overall survival was 70% at 2 years. FFDM was significantly associated with MP contact, maximum tumor dimension, and SUVmax, and these variables could be combined into an exploratory prognostic index that identified patients at highest risk for developing metastases. Conclusion In our cohort, noninvasive, imaging-based features were associated with distant progression after SABR for early stage NSCLC. If validated, our prognostic index could allow identification of patients who might benefit from systemic therapy after SABR.

Objective Primary squamous cell carcinoma (SCCA) of the vagina is a rare malignancy with limited data to guide treatment. We evaluated prognostic factors and outcomes for patients with primary vaginal SCCA treated with definitive radiation therapy at a single institution. Methods A retrospective analysis was performed on patients treated for primary vaginal SCCA from 1959 to 2011. Results Ninety-one patients with primary vaginal SCCA were treated with definitive radiation therapy. Thirty-eight patients had FIGO stage I, 28 stage II, 13 stage III, and 12 stage IV disease. The mean total dose was 70.1Gy. Two-year overall survival (OS), locoregional control rate (LRC), and distant metastasis-free survival by stage were, respectively: stage I: 96.2%, 80.6%, 87.5%; stage II: 92.3%, 64.7%, 84.6%; stage III: 66.6%, 44.4%, 50.0%; and stage IV: 25.0%, 14.3%, 25.0%. Treatment with total dose over 70Gy was associated with improved OS (p=0.0956) and LRC (p=0.055). There was a significant difference in median dose received by patients who developed grade 3/4 toxicity compared to those who did not (82.9Gy versus 70.0Gy, p=0.0019). None of the 10 patients treated with IMRT experienced locoregional recurrence or grade 3/4 toxicity. Tumor size larger than 4cm was associated with worse OS (p=0.0034) and LRC (p=0.006). Conclusions Our analysis suggests that the optimal dose for definitive treatment of SCCA of the vagina lies between 70 and 80Gy. Treatment with IMRT may allow for dose escalation with reduced toxicity and excellent LRC. Tumor size over 4cm is associated with inferior outcomes and may require additional treatment modalities.

152 Background: Palliative care’s role in oncology has expanded, but its impact on aggressiveness of care at the end of life has not been characterized at the population level. Methods: This matched retrospective cohort study examined the effect of an encounter with palliative care on healthcare utilization at the end of life among 6,580 Medicare beneficiaries with advanced prostate, breast, lung, or colorectal cancer. We compared healthcare utilization before and after palliative care consultation to a matched non-palliative care cohort. Results: The palliative care cohort had higher rates of healthcare utilization in the 30 days prior to palliative care consult compared to the non-palliative cohort, with higher rates of hospitalization (risk ratio [RR] 3.33; 95% CI 2.87-3.85), invasive procedures (RR 1.75; 95% CI 1.62-1.88), and chemotherapy administration (RR 1.61; 95% CI 1.45-1.78). The opposite pattern emerged in the interval from palliative care consultation through death, where the palliative care cohort had lower rates of hospitalization (RR 0.53; 95% CI 0.44-0.65), invasive procedures (RR 0.52; 95% CI 0.45-0.59), and chemotherapy administration (RR 0.46; 95% CI 0.39-0.53). Patients with early palliative care consultation had larger absolute reductions in healthcare utilization compared to those with palliative care consultation closer to the end of life. Conclusions: This population-based study found that palliative care substantially decreased healthcare utilization among Medicare beneficiaries with advanced cancer. Given the increasing number of elderly patients with advanced cancer, this study emphasizes the importance of early integration of palliative care alongside standard oncologic care.

Purpose: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. Methods: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated. Simultaneous integrated boost (SIB) 6 MV VMAT plans were produced for conventional and hypofractionated radiotherapy, using 30–70 and 100% cycle gating scenarios. Prescribed doses were 200 cGy with SIB to 240 cGy to high uptake volume for conventional, and 800 with SIB to 900 cGy for hypofractionated plans. Dose rates of 600 MU/min (conventional and hypofractionated) and flattening filter free 1400 MU/min (hypofractionated) were used. Ion chamber measurements were performed to verify delivered doses. Vials with A549 cells placed in locations matching ion chamber measurements were irradiated using the same plans to measure clonogenic survival. Differences in survival for the different doses, dose rates, gating windows, and breathing patterns were analyzed. Results: Ion chamber measurements agreed within 3% of the planned dose, for all locations, breathing patterns and gating windows. Cell survival depended on dose alone, and not on gating window, breathing pattern, MU rate, or delivery time. The surviving fraction varied from approximately 40% at 2Gy to 1% for 9 Gy and was within statistical uncertainty relative to that observed for the stationary phantom. Conclusions: Use of gated VMAT in PET-driven SIB radiotherapy was validated using ion chamber measurements and cell survival assays for conventional and hypofractionated radiotherapy.

e16608Background: Treatment decisions in localized prostate cancer hinge on an accurate estimation of patient survival, yet we lack robust survival prediction tools. Current cancer prediction model...

1008Background: Women with localized breast cancer face the difficult personal decision of whether to undergo mastectomy or breast conservation surgery (BCS). Multiple factors impact this decision,...

e15748Background: Numerous symptoms impact patient quality of life during and after a diagnosis of cancer. Among pancreatic cancer patients, common symptoms include pain, nausea and/or vomiting and...