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Intensity Modulated Radiation Therapy Utilization in the Treatment of Gastrointestinal Malignancies Between 2000 and 2009 in the SEER-Medicare Population
Volume 90 Number 1S Supplement 2014 recurrence rates for patients treated with IMRT using dose painting or sequential boost techniques. Author Disclosure: C.R. Spencer: None. M. Cardenas: None. T.A. DeWees: None. R. Jain: None. P. Grigsby: None. B. Tan: None. M. Silviera: None. S. Hunt: None. R.J. Myerson: None. P.J. Parikh: None. J.R. Olsen: G. Consultant; DFine, Inc. I. Travel Expenses; DFine, Inc, RSNA Resident & Fellow Committee.
2473 Comparison of Conditional Survival in Patients With Gastrointestinal Malignancies Treated With Radiation: A Population-Based Analysis A.J. Patel, J. Daniels, J. Vincent, and T. Eng; University of Texas Health Science Center San Antonio, San Antonio, TX Purpose/Objective(s): Survival probability is not a static measure after diagnosis and treatment. At the time of diagnosis, patients are given survival outcomes which are determined from the time of diagnosis. Conditional survival (CS) statistics try to accurately determine the probability of survival after a designated period of time by taking into account continuously changing hazard rates over time. Patients who survive the first couple of years after treatment are presumed to have passed a window of disease recurrence or spread. CS modeling may help direct treatment selection and post-treatment surveillance. Gastrointestinal malignancies make up a substantial portion of newly diagnosed cancer cases and were evaluated in this project. Materials/Methods: A total of 69,078 cases of gastrointestinal malignancies (groups Z esophagus, stomach, pancreas, rectum, anal and hepatobiliary) diagnosed from 1998-2010 were identified from the Surveillance, Epidemiology, and End Results (SEER 18) program who were treated with radiation. Cases which were included had the designation of “local” or “regional” disease and were recorded as having received beam radiation and/or brachytherapy. Five year CS models were determined for each anatomic group based on the SEER data dictionary for patients who had already survived up to 5 years from diagnosis. Observed survival (OS) data were also obtained. Results: The group with the greatest change in CS was pancreas which showed an improvement in 5-yr CS of 39.2%. The groups with the least change in CS were rectal and anal primaries which showed an improvement in 5-yr CS of 1.4% and 5.1% respectively. The greatest magnitude of difference between OS and CS at 5 years were for the groups pancreas, esophagus and hepatobiliary at 78%, 70% and73% respectively. The least magnitude of difference between OS and CS at 5 years were for the rectum and anal groups at 31% and 32% respectively. Conclusions: All groups of gastrointestinal malignancies were noted to have an improvement in CS with the greatest magnitude in pancreatic and hepatobiliary primaries but closely followed by esophageal and stomach primaries. Rectal and anal malignancies were noted to have the least improvement in CS most likely related to the effectiveness of treatment. This data has important implications regarding post-therapy surveillance of gastrointestinal malignancies as CS statistics aim to accurately determine the probability of survival by accounting for continuously changing hazard rates over time. Author Disclosure: A.J. Patel: None. J. Daniels: None. J. Vincent: None. T. Eng: None.
2474 Robotic Stereotactic Body Radiation Therapy in Patients With Recurrent or Metastatic Abdominopelvic Tumors: A Single-Institute Experience D. Sezen, M. Gurkaynak, M. Gultekin, M. Cengiz, F. Yildiz, F. Zorlu, F. Akyol, G. Yazici, P. Hurmuz, and G. Ozyigit; Department of Radiation Oncology, Hacettepe University, Faculty of Medicine, Ankara, Turkey Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) has been used successfully to treat patients with extracranial malignancies. The aim of this study was to evaluate efficacy and toxicity of robotic Cyberknife (Accuray, Sunnyvale, CA)-based SBRT in patients with recurrent or metastatic abdominopelvic tumors.
Poster Viewing Abstracts S401 Materials/Methods: A total of 69 patients treated between May 2008 and January 2011 were retrospectively evaluated. Thirty-eight (55%) patients were reirradiated for local recurrence and 31 (45%) patients were treated for the first time. The median age was 59 years (range, 24-86 years). There were 31 (45%) male and 38 (55%) female patients. The median total dose was 30 Gy (range, 15-60 Gy) delivered with a median 3 fractions (range, 2-5 fraction). The tumor response to treatment was assessed by computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET). Results: At 12 months (range, 2-44 months) median follow-up, local control was 65% median overall survival (OS) was 23 months. The longest survival (median, 36 months) was observed in the patients with adrenal gland metastasis and the shortest (median, 11.5 months) with gynecologic tumors. A larger gross tumor volume (116 cc) was significantly correlated with worse OS (median, 11 months). Grade 3-4 acute and late toxicity were seen in 7% and 14.5% of patients, respectively. Late toxicity was significantly higher in pelvic tumors than in abdominal tumors (26% vs 5%, p Z 0.035). Conclusions: SBRT seems to be feasible and resulted in good treatment outcomes in patients with recurrent or metastatic abdominopelvic tumors. Author Disclosure: D. Sezen: None. M. Gurkaynak: None. M. Gultekin: None. M. Cengiz: None. F. Yildiz: None. F. Zorlu: None. F. Akyol: None. G. Yazici: None. P. Hurmuz: None. G. Ozyigit: None.
2475 Intensity Modulated Radiation Therapy Utilization in the Treatment of Gastrointestinal Malignancies Between 2000 and 2009 in the SEER-Medicare Population M. Palta,1 B.G. Czito,1 C.G. Willett,1 and M.A. Dinan2; 1Duke University Medical Center, Durham, NC, 2Duke Clinical Research Institute, Durham, NC Purpose/Objective(s): Intensity modulated radiation therapy (IMRT) is a novel approach to radiation treatment planning and delivery. Numerous dosimetric studies in gastrointestinal (GI) malignancies have shown that the integration of IMRT is feasible and, when compared with conventional radiation therapy approaches, results in improved normal tissue sparing. Retrospective comparisons have demonstrated improvements in acute and late toxicity rates with selected studies demonstrating superior treatment outcomes with IMRT. Randomized trials comparing conventional radiation therapy with IMRT are sparse. Despite limited data evaluating the incremental value of IMRT over conventional radiation therapy, increased utilization of IMRT has been observed in the treatment of breast, prostate and head and neck malignancies. In this study we examined IMRT utilization in the treatment of GI malignancies using Surveillance, Epidemiology, and End Results Program (SEER)-Medicare linked data. Materials/Methods: This study is a retrospective claims-based analysis of SEER-Medicare patients diagnosed with GI malignancy between 2000 and 2009. Radiation therapy, and specifically IMRT use, was assessed over time. Unadjusted and adjusted regression analysis was performed to assess factors associated with receipt of IMRT. Results: A total of 135,807 patients with GI malignancies were identified of which 14,514 received external beam RT (11%). Among patients undergoing external beam RT, IMRT utilization increased with time from <0.1% of cases in 2000-2001, 4.7% in 2002-2003, 11.4% in 2004-2005, 23.1% in 2006-2007 to 37.3% of cases in 2008-2009 (p<0.0001). Of patients receiving radiation therapy, thirty percent or more of GI patients from each sub-site (anal, colorectal, esophagus, liver/hepatobiliary, pancreas, and stomach) were treated with IMRT by 2009, with more than half of patients with anal and pancreatic malignancies undergoing IMRT by 2009. On adjusted regression analysis, age, race, comorbidity, socioeconomic status and marital status were not associated with use of IMRT. Factors associated with receipt of IMRT in adjusted analyses including living within the Northeast (OR 1.53, 1.01-2.33), South (OR 2.68, 1.564.63) or West (OR 2.53, 1.48-4.33) compared with the Midwest, later year of diagnosis, and non-colorectal GI cancer sub-site. Conclusions: Analysis of SEER-Medicare data from 2000-2009 indicates increasing utilization of IMRT in the management of patients with GI malignancies.
S402
International Journal of Radiation Oncology Biology Physics
Author Disclosure: M. Palta: None. B.G. Czito: None. C.G. Willett: None. M.A. Dinan: None.
variates common to both the NODA and the Surveillance, Epidemiology, and End Results (SEER) database yielded similar results, demonstrating congruence between the two databases. Results: Median follow-up was 8.4 years. MVA demonstrated that dose (categorical, 68-82 Gy divided into 2 Gy bins), T-stage, grade, marital status, age, and ADT were significant predictors of OS. Race was not significant. Hazard ratios for OS in all patients declined monotonically with increasing dose, reaching 0.57 (95% Confidence Interval [CI] 0.450.73) at 80-82 Gy, without evidence of a plateau. The Kaplan-Meier curves showed a clear and statistically significant dose response relationship for OS (p<0.0001). Even when compared to the 74-76 Gy group (HR Z 0.78 CI 0.71-0.86), 80-82 Gy still maintained a significant OS benefit. Compared to a baseline of 68-70 Gy, the predicted increase in median survival is 1.7 years with 74-76 Gy and 4.1 years with 80-82 Gy. The dose response persisted when patients treated with and without ADT were analyzed separately. Subset analysis confirmed the strongest dose response in the high risk category, and the evidence for a dose response above 72 Gy in the low risk group was less conclusive. Although dose and treatment year were correlated, dose remained significant when treatment year was included in the MVA. Conclusions: Increasing dose significantly improved OS in prostate cancer patients treated with EBRT in a national population-based cohort. This effect was observed for doses in the currently acceptable range for dose escalation, but cannot be assessed beyond 82 Gy. The treatment year effect may indicate improved overall survival with improved treatment technique. Author Disclosure: M.D. Hall: A. Employee; City of Hope National Medical Center. T.E. Schultheiss: A. Employee; City of Hope National Medical Center. D.D. Smith: A. Employee; City of Hope National Medical Center. B.P. Tseng: A. Employee; Duke University Medical Center. J.Y.C. Wong: A. Employee; City of Hope National Medical Center.
2476 Low-Dose Aspirin Mitigates Acute Radiation-Induced Genitourinary Toxicity in Patients With Prostate Adenocarcinoma J.L. Mikell,1 W.A. Hall,1 D.C. Nickleach,1 N.K. Jegadeesh,2 P.J. Rossi,2 and A.B. Jani2; 1Emory University, Atlanta, GA, 2Emory University, Atlanta, GA Purpose/Objective(s): Patients treated with radiation therapy for prostate adenocarcinoma (PCA) experience both acute and late genitourinary (GU) and gastrointestinal (GI) toxicity. Recent publications indicate a possible association between aspirin use and GI toxicity during radiation therapy for PCA. We sought to assess the effect of daily low-dose aspirin on acute and late GI and GU toxicity associated with radiation therapy for PCA in a large patient population. Materials/Methods: We queried an IRB-monitored, prospectively-acquired database of patients treated for PCA at our affiliated hospitals. For patients treated with definitive radiation therapy for PCA, we measured the association between aspirin use and Common Terminology Criteria for Adverse Events (CTCAE) GI/GU toxicity scores. Patient and treatmentrelated factors, such as age, race, total dose, T stage, hormonal therapy, use of pelvic nodal irradiation, length of time with acute toxicity records, and follow-up time were used as covariates. Univariate and multivariate analyses were performed using ordinal logistic regression models. Results: Between 1991 and 2013, 972 patients were eligible for analysis. 210 patients were on daily low-dose aspirin during treatment. On multivariate analysis, aspirin use was significantly associated with reduced acute GU toxicity (OR 0.73, 95% CI Z 0.55-0.99, p Z 0.040). There was no statistically significant worsening of acute GI (OR 0.77, 95% CI Z 0.581.03, p Z 0.079) or late GU toxicity (OR 0.93, 95% CI Z 0.69-1.25, p Z 0.632) associated with aspirin use. There was a trend for reduced late GI toxicity in patients taking daily aspirin (OR 0.69, 95% CI Z 0.48-1.01, p Z 0.056). Conclusions: Aspirin use was independently associated with reduced acute GU toxicity in patients undergoing radiation therapy for PCA. Late GU and GI toxicity were not worsened by aspirin use during radiation, and late GI toxicity trended towards improvement with aspirin use. While these results require validation in a prospective study, aspirin use during radiation therapy for PCA should be considered, as low-dose aspirin is a safe, inexpensive medication already separately recommended for many patients planned for radiation therapy. Author Disclosure: J.L. Mikell: None. W.A. Hall: None. D.C. Nickleach: None. N.K. Jegadeesh: None. P.J. Rossi: None. A.B. Jani: None.
2477 Improved Overall Survival in Prostate Cancer With Increasing Dose M.D. Hall,1 T.E. Schultheiss,1 D.D. Smith,1 B.P. Tseng,2 and J.Y.C. Wong1; 1City of Hope National Medical Center, Duarte, CA, 2 Duke University Medical Center, Raleigh-Durham, NC Purpose/Objective(s): To assess the impact of increasing dose on overall survival (OS) for prostate cancer patients. Materials/Methods: Treatment data were obtained on all patients treated for prostate cancer between 1990 and 2006 in the National Oncology Data Alliance (NODA), a proprietary database of merged tumor registries (Elekta/IMPAC Medical Systems, Inc., Sunnyvale, CA). All participating registries meet American College of Surgeons (ACOS) standards. Eligible patients were treated with definitive external beam radiation therapy (EBRT) and had complete data on dose, T-stage, use of hormonal therapy (ADT), and treatment start dates. In ACOS registries, Gleason scores are binned into four grades. PSA values were not available. Patients with a history of prior malignancy were excluded, leaving 17,603 evaluable patients. Multivariate proportional hazards analysis (MVA) was used to identify factors associated with OS. Survival curves were plotted using the Kaplan-Meier method and compared using the log-rank test. MVA with
2478 Long-Term Outcome of Prostate Cancer Patients Who Fail Salvage Radiation Therapy and Radical Prostatectomy J. Ying,1 J. Yan,1 C. Roehrborn,1 Y. Lotan,1 X. Xie,1 D. Pistenmaa,1 S. Liauw,2 and D. Kim1; 1UT Southwestern, Dallas, TX, 2University of Chicago, Chicago, IL Purpose/Objective(s): Salvage radiation therapy (SRT) is an effective treatment for prostate cancer (PCa) that recurs after radical prostatectomy. Long-term follow-up (f/u) in men who developed biochemical recurrence (BCR) after SRT is less well described in literature. We hypothesized that SRT would lead to sustained improvement in prostate specific outcome. The goal of this study is to report on the natural history of patients (pts) treated with SRT > 13 years (y) ago. Materials/Methods: 61 pts with PCa treated with SRT without hormone therapy during 1992-2000 at our institution were identified. Survival was calculated using the Kaplan-Meier method. Log-rank test and Cox regression were used to determine significance of clinical parameters with outcome. Results: This study is one of the longest experiences for SRT reported in literature with a median f/u of 10.5 y (3-238 months (m)). Median SRT dose was 64.8 Gray. Med age at SRT was 62 (46-83), 15% of pts had pathologic Gleason score (pGS) 8-10 disease, 14% had pre-surgical PSA > 20, 63% had pT3+ disease, and 59% had positive margin at time of surgery. Median pre-SRT PSA was 0.45 (0.06-11.9). Of 61 pts, 34 (56%) had PSA failure after SRT. 5-y and 10-y freedom from PSA failure (FFPF) were 51% and 33%. 10 y PCa-specific survival (PCSS) and distant metastasis free survival (DMFS) were 84% and 84% respectively. pGS > Z 8 (p Z .0056; HR 5.1, 1.6-16.0), seminal vesicle invasion (p Z .036, HR 2.1, 1.0-4.2), lymphovascular invasion (p Z .035, HR 5.3, 0.9-32.2), and pre-SRT PSA (p Z .015, HR 2.3, 1.1-4.5) were associated with decreased FFPF. For the 34 pts who had BCR, median f/u was 157.5 m (13-238). Median time to BCR following SRT was 30 m (3-138). 19 (56%) required androgen deprivation therapy (ADT). Median time from BCR to initiating ADT was 48 m (0-151). Outcome after BCR is as follows. OS at
2473 Comparison of Conditional Survival in Patients With Gastrointestinal Malignancies Treated With Radiation: A Population-Based Analysis A.J. Patel, J. Daniels, J. Vincent, and T. Eng; University of Texas Health Science Center San Antonio, San Antonio, TX Purpose/Objective(s): Survival probability is not a static measure after diagnosis and treatment. At the time of diagnosis, patients are given survival outcomes which are determined from the time of diagnosis. Conditional survival (CS) statistics try to accurately determine the probability of survival after a designated period of time by taking into account continuously changing hazard rates over time. Patients who survive the first couple of years after treatment are presumed to have passed a window of disease recurrence or spread. CS modeling may help direct treatment selection and post-treatment surveillance. Gastrointestinal malignancies make up a substantial portion of newly diagnosed cancer cases and were evaluated in this project. Materials/Methods: A total of 69,078 cases of gastrointestinal malignancies (groups Z esophagus, stomach, pancreas, rectum, anal and hepatobiliary) diagnosed from 1998-2010 were identified from the Surveillance, Epidemiology, and End Results (SEER 18) program who were treated with radiation. Cases which were included had the designation of “local” or “regional” disease and were recorded as having received beam radiation and/or brachytherapy. Five year CS models were determined for each anatomic group based on the SEER data dictionary for patients who had already survived up to 5 years from diagnosis. Observed survival (OS) data were also obtained. Results: The group with the greatest change in CS was pancreas which showed an improvement in 5-yr CS of 39.2%. The groups with the least change in CS were rectal and anal primaries which showed an improvement in 5-yr CS of 1.4% and 5.1% respectively. The greatest magnitude of difference between OS and CS at 5 years were for the groups pancreas, esophagus and hepatobiliary at 78%, 70% and73% respectively. The least magnitude of difference between OS and CS at 5 years were for the rectum and anal groups at 31% and 32% respectively. Conclusions: All groups of gastrointestinal malignancies were noted to have an improvement in CS with the greatest magnitude in pancreatic and hepatobiliary primaries but closely followed by esophageal and stomach primaries. Rectal and anal malignancies were noted to have the least improvement in CS most likely related to the effectiveness of treatment. This data has important implications regarding post-therapy surveillance of gastrointestinal malignancies as CS statistics aim to accurately determine the probability of survival by accounting for continuously changing hazard rates over time. Author Disclosure: A.J. Patel: None. J. Daniels: None. J. Vincent: None. T. Eng: None.
2474 Robotic Stereotactic Body Radiation Therapy in Patients With Recurrent or Metastatic Abdominopelvic Tumors: A Single-Institute Experience D. Sezen, M. Gurkaynak, M. Gultekin, M. Cengiz, F. Yildiz, F. Zorlu, F. Akyol, G. Yazici, P. Hurmuz, and G. Ozyigit; Department of Radiation Oncology, Hacettepe University, Faculty of Medicine, Ankara, Turkey Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) has been used successfully to treat patients with extracranial malignancies. The aim of this study was to evaluate efficacy and toxicity of robotic Cyberknife (Accuray, Sunnyvale, CA)-based SBRT in patients with recurrent or metastatic abdominopelvic tumors.
Poster Viewing Abstracts S401 Materials/Methods: A total of 69 patients treated between May 2008 and January 2011 were retrospectively evaluated. Thirty-eight (55%) patients were reirradiated for local recurrence and 31 (45%) patients were treated for the first time. The median age was 59 years (range, 24-86 years). There were 31 (45%) male and 38 (55%) female patients. The median total dose was 30 Gy (range, 15-60 Gy) delivered with a median 3 fractions (range, 2-5 fraction). The tumor response to treatment was assessed by computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET). Results: At 12 months (range, 2-44 months) median follow-up, local control was 65% median overall survival (OS) was 23 months. The longest survival (median, 36 months) was observed in the patients with adrenal gland metastasis and the shortest (median, 11.5 months) with gynecologic tumors. A larger gross tumor volume (116 cc) was significantly correlated with worse OS (median, 11 months). Grade 3-4 acute and late toxicity were seen in 7% and 14.5% of patients, respectively. Late toxicity was significantly higher in pelvic tumors than in abdominal tumors (26% vs 5%, p Z 0.035). Conclusions: SBRT seems to be feasible and resulted in good treatment outcomes in patients with recurrent or metastatic abdominopelvic tumors. Author Disclosure: D. Sezen: None. M. Gurkaynak: None. M. Gultekin: None. M. Cengiz: None. F. Yildiz: None. F. Zorlu: None. F. Akyol: None. G. Yazici: None. P. Hurmuz: None. G. Ozyigit: None.
2475 Intensity Modulated Radiation Therapy Utilization in the Treatment of Gastrointestinal Malignancies Between 2000 and 2009 in the SEER-Medicare Population M. Palta,1 B.G. Czito,1 C.G. Willett,1 and M.A. Dinan2; 1Duke University Medical Center, Durham, NC, 2Duke Clinical Research Institute, Durham, NC Purpose/Objective(s): Intensity modulated radiation therapy (IMRT) is a novel approach to radiation treatment planning and delivery. Numerous dosimetric studies in gastrointestinal (GI) malignancies have shown that the integration of IMRT is feasible and, when compared with conventional radiation therapy approaches, results in improved normal tissue sparing. Retrospective comparisons have demonstrated improvements in acute and late toxicity rates with selected studies demonstrating superior treatment outcomes with IMRT. Randomized trials comparing conventional radiation therapy with IMRT are sparse. Despite limited data evaluating the incremental value of IMRT over conventional radiation therapy, increased utilization of IMRT has been observed in the treatment of breast, prostate and head and neck malignancies. In this study we examined IMRT utilization in the treatment of GI malignancies using Surveillance, Epidemiology, and End Results Program (SEER)-Medicare linked data. Materials/Methods: This study is a retrospective claims-based analysis of SEER-Medicare patients diagnosed with GI malignancy between 2000 and 2009. Radiation therapy, and specifically IMRT use, was assessed over time. Unadjusted and adjusted regression analysis was performed to assess factors associated with receipt of IMRT. Results: A total of 135,807 patients with GI malignancies were identified of which 14,514 received external beam RT (11%). Among patients undergoing external beam RT, IMRT utilization increased with time from <0.1% of cases in 2000-2001, 4.7% in 2002-2003, 11.4% in 2004-2005, 23.1% in 2006-2007 to 37.3% of cases in 2008-2009 (p<0.0001). Of patients receiving radiation therapy, thirty percent or more of GI patients from each sub-site (anal, colorectal, esophagus, liver/hepatobiliary, pancreas, and stomach) were treated with IMRT by 2009, with more than half of patients with anal and pancreatic malignancies undergoing IMRT by 2009. On adjusted regression analysis, age, race, comorbidity, socioeconomic status and marital status were not associated with use of IMRT. Factors associated with receipt of IMRT in adjusted analyses including living within the Northeast (OR 1.53, 1.01-2.33), South (OR 2.68, 1.564.63) or West (OR 2.53, 1.48-4.33) compared with the Midwest, later year of diagnosis, and non-colorectal GI cancer sub-site. Conclusions: Analysis of SEER-Medicare data from 2000-2009 indicates increasing utilization of IMRT in the management of patients with GI malignancies.
S402
International Journal of Radiation Oncology Biology Physics
Author Disclosure: M. Palta: None. B.G. Czito: None. C.G. Willett: None. M.A. Dinan: None.
variates common to both the NODA and the Surveillance, Epidemiology, and End Results (SEER) database yielded similar results, demonstrating congruence between the two databases. Results: Median follow-up was 8.4 years. MVA demonstrated that dose (categorical, 68-82 Gy divided into 2 Gy bins), T-stage, grade, marital status, age, and ADT were significant predictors of OS. Race was not significant. Hazard ratios for OS in all patients declined monotonically with increasing dose, reaching 0.57 (95% Confidence Interval [CI] 0.450.73) at 80-82 Gy, without evidence of a plateau. The Kaplan-Meier curves showed a clear and statistically significant dose response relationship for OS (p<0.0001). Even when compared to the 74-76 Gy group (HR Z 0.78 CI 0.71-0.86), 80-82 Gy still maintained a significant OS benefit. Compared to a baseline of 68-70 Gy, the predicted increase in median survival is 1.7 years with 74-76 Gy and 4.1 years with 80-82 Gy. The dose response persisted when patients treated with and without ADT were analyzed separately. Subset analysis confirmed the strongest dose response in the high risk category, and the evidence for a dose response above 72 Gy in the low risk group was less conclusive. Although dose and treatment year were correlated, dose remained significant when treatment year was included in the MVA. Conclusions: Increasing dose significantly improved OS in prostate cancer patients treated with EBRT in a national population-based cohort. This effect was observed for doses in the currently acceptable range for dose escalation, but cannot be assessed beyond 82 Gy. The treatment year effect may indicate improved overall survival with improved treatment technique. Author Disclosure: M.D. Hall: A. Employee; City of Hope National Medical Center. T.E. Schultheiss: A. Employee; City of Hope National Medical Center. D.D. Smith: A. Employee; City of Hope National Medical Center. B.P. Tseng: A. Employee; Duke University Medical Center. J.Y.C. Wong: A. Employee; City of Hope National Medical Center.
2476 Low-Dose Aspirin Mitigates Acute Radiation-Induced Genitourinary Toxicity in Patients With Prostate Adenocarcinoma J.L. Mikell,1 W.A. Hall,1 D.C. Nickleach,1 N.K. Jegadeesh,2 P.J. Rossi,2 and A.B. Jani2; 1Emory University, Atlanta, GA, 2Emory University, Atlanta, GA Purpose/Objective(s): Patients treated with radiation therapy for prostate adenocarcinoma (PCA) experience both acute and late genitourinary (GU) and gastrointestinal (GI) toxicity. Recent publications indicate a possible association between aspirin use and GI toxicity during radiation therapy for PCA. We sought to assess the effect of daily low-dose aspirin on acute and late GI and GU toxicity associated with radiation therapy for PCA in a large patient population. Materials/Methods: We queried an IRB-monitored, prospectively-acquired database of patients treated for PCA at our affiliated hospitals. For patients treated with definitive radiation therapy for PCA, we measured the association between aspirin use and Common Terminology Criteria for Adverse Events (CTCAE) GI/GU toxicity scores. Patient and treatmentrelated factors, such as age, race, total dose, T stage, hormonal therapy, use of pelvic nodal irradiation, length of time with acute toxicity records, and follow-up time were used as covariates. Univariate and multivariate analyses were performed using ordinal logistic regression models. Results: Between 1991 and 2013, 972 patients were eligible for analysis. 210 patients were on daily low-dose aspirin during treatment. On multivariate analysis, aspirin use was significantly associated with reduced acute GU toxicity (OR 0.73, 95% CI Z 0.55-0.99, p Z 0.040). There was no statistically significant worsening of acute GI (OR 0.77, 95% CI Z 0.581.03, p Z 0.079) or late GU toxicity (OR 0.93, 95% CI Z 0.69-1.25, p Z 0.632) associated with aspirin use. There was a trend for reduced late GI toxicity in patients taking daily aspirin (OR 0.69, 95% CI Z 0.48-1.01, p Z 0.056). Conclusions: Aspirin use was independently associated with reduced acute GU toxicity in patients undergoing radiation therapy for PCA. Late GU and GI toxicity were not worsened by aspirin use during radiation, and late GI toxicity trended towards improvement with aspirin use. While these results require validation in a prospective study, aspirin use during radiation therapy for PCA should be considered, as low-dose aspirin is a safe, inexpensive medication already separately recommended for many patients planned for radiation therapy. Author Disclosure: J.L. Mikell: None. W.A. Hall: None. D.C. Nickleach: None. N.K. Jegadeesh: None. P.J. Rossi: None. A.B. Jani: None.
2477 Improved Overall Survival in Prostate Cancer With Increasing Dose M.D. Hall,1 T.E. Schultheiss,1 D.D. Smith,1 B.P. Tseng,2 and J.Y.C. Wong1; 1City of Hope National Medical Center, Duarte, CA, 2 Duke University Medical Center, Raleigh-Durham, NC Purpose/Objective(s): To assess the impact of increasing dose on overall survival (OS) for prostate cancer patients. Materials/Methods: Treatment data were obtained on all patients treated for prostate cancer between 1990 and 2006 in the National Oncology Data Alliance (NODA), a proprietary database of merged tumor registries (Elekta/IMPAC Medical Systems, Inc., Sunnyvale, CA). All participating registries meet American College of Surgeons (ACOS) standards. Eligible patients were treated with definitive external beam radiation therapy (EBRT) and had complete data on dose, T-stage, use of hormonal therapy (ADT), and treatment start dates. In ACOS registries, Gleason scores are binned into four grades. PSA values were not available. Patients with a history of prior malignancy were excluded, leaving 17,603 evaluable patients. Multivariate proportional hazards analysis (MVA) was used to identify factors associated with OS. Survival curves were plotted using the Kaplan-Meier method and compared using the log-rank test. MVA with
2478 Long-Term Outcome of Prostate Cancer Patients Who Fail Salvage Radiation Therapy and Radical Prostatectomy J. Ying,1 J. Yan,1 C. Roehrborn,1 Y. Lotan,1 X. Xie,1 D. Pistenmaa,1 S. Liauw,2 and D. Kim1; 1UT Southwestern, Dallas, TX, 2University of Chicago, Chicago, IL Purpose/Objective(s): Salvage radiation therapy (SRT) is an effective treatment for prostate cancer (PCa) that recurs after radical prostatectomy. Long-term follow-up (f/u) in men who developed biochemical recurrence (BCR) after SRT is less well described in literature. We hypothesized that SRT would lead to sustained improvement in prostate specific outcome. The goal of this study is to report on the natural history of patients (pts) treated with SRT > 13 years (y) ago. Materials/Methods: 61 pts with PCa treated with SRT without hormone therapy during 1992-2000 at our institution were identified. Survival was calculated using the Kaplan-Meier method. Log-rank test and Cox regression were used to determine significance of clinical parameters with outcome. Results: This study is one of the longest experiences for SRT reported in literature with a median f/u of 10.5 y (3-238 months (m)). Median SRT dose was 64.8 Gray. Med age at SRT was 62 (46-83), 15% of pts had pathologic Gleason score (pGS) 8-10 disease, 14% had pre-surgical PSA > 20, 63% had pT3+ disease, and 59% had positive margin at time of surgery. Median pre-SRT PSA was 0.45 (0.06-11.9). Of 61 pts, 34 (56%) had PSA failure after SRT. 5-y and 10-y freedom from PSA failure (FFPF) were 51% and 33%. 10 y PCa-specific survival (PCSS) and distant metastasis free survival (DMFS) were 84% and 84% respectively. pGS > Z 8 (p Z .0056; HR 5.1, 1.6-16.0), seminal vesicle invasion (p Z .036, HR 2.1, 1.0-4.2), lymphovascular invasion (p Z .035, HR 5.3, 0.9-32.2), and pre-SRT PSA (p Z .015, HR 2.3, 1.1-4.5) were associated with decreased FFPF. For the 34 pts who had BCR, median f/u was 157.5 m (13-238). Median time to BCR following SRT was 30 m (3-138). 19 (56%) required androgen deprivation therapy (ADT). Median time from BCR to initiating ADT was 48 m (0-151). Outcome after BCR is as follows. OS at