Results of Scanning Beam Proton Therapy (SCBT) for the Treatment of Patients With High-Risk Prostate Cancer

Results of Scanning Beam Proton Therapy (SCBT) for the Treatment of Patients With High-Risk Prostate Cancer

Volume 93  Number 3S  Supplement 2015 and the median time to nadir was 39 months (2 to 89 months). The 5-year bPFS rate was 95.4%. The 5-year distan...

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Volume 93  Number 3S  Supplement 2015 and the median time to nadir was 39 months (2 to 89 months). The 5-year bPFS rate was 95.4%. The 5-year distant metastasis-free, cause-specific, and overall survival rates were 98.9%, 99.6%, and 95.3%, respectively. On multivariate analysis, the number of intermediate-risk factors (1 vs multiple) significantly predicted biochemical recurrence (hazard ratio [HR] 0.4, PZ.028) as patients with multiple risk factors had worse biochemical control. The use of ADT did not significantly improve biochemical control at 5 years (HR 1.8, PZ.325). A separate multivariate analysis was performed including only patients with 10 or more zones biopsied at the time of diagnosis. The number of intermediate-risk factors remained a predictor of biochemical relapse-free survival (HR 0.3, PZ.037). A primary Gleason score of 4 (4+3Z7) versus a primary Gleason score of 3 (3+3Z6 or 3+4Z7) also predicted worse biochemical control (HR 0.2, PZ0.028). Conclusion: PT provided excellent biochemical control for patients with intermediate-risk prostate cancer. Multiple intermediate-risk factors significantly increased the risk for biochemical failure. In patients with at least a 10-zone biopsy, a primary Gleason score of 4 also predicted worse biochemical relapse-free survival. Short-term ADT did not improve biochemical control, but selection bias likely mitigated its effects. Author Disclosure: C.M. Bryant: None. W.M. Mendenhall: None. B.S. Hoppe: None. R.H. Henderson: None. R. Nichols: None. Z. Su: None. C.R. Williams: None. C.G. Morris: None. Z. Li: None. N.P. Mendenhall: None.

2604 Focal Nodal SBRT or Elective Nodal Protracted Salvage Radiation Therapy for Prostate Cancer Patients With a Choline PET-CT Positive Nodal Relapse G. Crehange,1 P. Maingon,2 A. Cueff,2 G. Truc,3 K. Peignaux,4 F. Mazoyer,3 N. Vulquin,1 M. Quivrin,1 S. Naudy,1 and E. Martin1; 1Centre Georges-Francois Leclerc, Dijon Cedex, France, 2Centre Georges Franc¸ois Leclerc, Dijon, France, 3Centre Georges Franc¸ois Leclerc, Dijon, France, 4Centre GF Leclerc, Dijon, France Purpose/Objective(s): 18F or 11C choline positron emission tomographyecomputed tomography (PET-CT) has significantly improved the detection of occult nodal relapse in prostate cancer patients with a rising prostate-specific antigen (PSA) level after radical prostatectomy and/or external radiation therapy (RT). In parallel, focal hypofractionated stereotactic body RT (fSBRT) is an emerging salvage RT (sRT) for oligometastatic diseases. It allows delivery of a very high biologically effective dose (BED) in few fractions but to a small volume (e.g., involved node only). In this preliminary report, we aimed to assess short-term biochemical response of focal SBRT versus protracted ENI in node-positive recurrent prostate cancer on choline PET-CT. Materials/Methods: Between 2009 and 2014, 102 patients underwent choline PET-TDM in our center. Of these, 37 had sRT without hormones for nodal relapse only. Patients underwent either fSBRT (nZ28) or protracted elective nodal irradiation (nZ 9) combined with a protracted boost to positive nodes (pENI). Patients treated with fSBRT received 30 to 45 Gy in 3 to 6 fractions while patients treated with pENI had 60 to 66Gy in 25 to 33 fractions. Failure was defined as PSA rising higher than pre-sRT on 2 consecutive samples or the initiation of any second salvage therapy. PSA nadir (nPSA), time to nPSA, and time to failure (TTF) were assessed. Results: The characteristics of patients and tumor at time of relapse were similar. The median PSA values at the time of sRT were 5.9 ng/mL (1.3; 17.3) with fSBRT and 6.9 ng/mL (0.5; 13.8) with pENI (PZNS); The median follow-up was 1.95 years (95% CI: 0.54-1.52). Fifteen failures occurred with fSBRT (51.7%) and 4 failures with pENI (44.4%). The median PSA nadir at 2 years was 0.57 (0.01-4.52) with fSBRT and 0.02 (0.01-0.07) with pENI (PZ.0004). The time to nPSA at 2 years was 17.61 months (0.20-23.62) with fSBRT and 8.46 months (5.19-18.37) with pENI (PZ.05). The median TTF was 2.89 years (95% CI: 1.24-4.65) with fSBRT and 4.73 years (95% CI: 0.40-ND) with pENI (PZ NS). Conclusion: Patients with a nodal relapse on fluorocholine PET-CT who were treated with pENI experienced a lower nPSA and shorter time to nPSA 2 years following completion of sRT than with fSBRT, consistent

Poster Viewing Session E243 with the eradication of micrometastatic disease in PET-negative nodes. Whether this translates into improved biochemical control and/or a clinical relapse needs longer follow-up. Author Disclosure: G. Crehange: None. P. Maingon: None. A. Cueff: None. G. Truc: None. K. Peignaux: None. F. Mazoyer: None. N. Vulquin: None. M. Quivrin: None. S. Naudy: None. E. Martin: None.

2605 Are Results From Intermediate-Risk Prostate Cancer Patients Treated Within Clinical Trials Applicable to Real Life? D. Taussky,1 J.P. Bahary,2 C. Lambert,1 M.C. Beauchemin,2 G. Delouya,1 M. Barkati,3 and X. Liem4; 1Centre Hospitalier de l’Universite de Montreal, Montreal, QC, Canada, 2Hopital Notre-Dame du CHUM, Montreal, QC, Canada, 3Centre Hospitalier de l’Universite´ de Montre´al (CHUM), Montreal, QC, Canada, 4Univesrite Montreal, Montreal, QC, Canada Purpose/Objective(s): There is some doubt on whether clinical studies (CSs) have selective inclusion criteria that might not represent real-life patients (RLPs) and may limit their applicability to daily clinical practice. Patients in CSs and RLPs might have different comorbidities which can have an impact on overall survival. We assessed whether patients from CSs differ from patients not included in terms of comorbidity, prostate cancer aggressiveness, and biochemical recurrence. Materials/Methods: We identified 468 patients with D’Amico intermediaterisk prostate cancer from our institutional database all treated with external beam radiation therapy only. Three hundred seven patients were treated in a CS, including 2, multinational randomized trials (PROFIT and RTOG 0126), each including >80 patients from our center; one in-house phase 2 with >40 patients and some smaller randomized studies with <13 patients each. These CS patients were compared to 161 patients (RLPs) who were not included in any CS. Patients treated in CSs were compared to the RLPs using nonparametric tests. Logistic regression was performed to explore predictive factors of CS inclusion. Biochemical recurrence rate was estimated using the Kaplan-Meier method and compared using the log-rank test. Results: Median follow-up was 56 months (interquartile range 36-78 months). There was no difference in age (mean 70 years for both, PZ.95) or in cancer aggressiveness between both groups: PSA >10 ng/mL in 28% of CS patients and in 32% of RLPs (PZ.37). Gleason score 4+3 was found in 29% of CS patients and in 30% of RLPs (PZ.58). CS patients had more frequently hypertension (60% CS vs 46% RLPs, PZ.01), and more often hypercholesterolemia (51% for CS vs 43% in RLPs, PZ.01). In univariate analysis, myocardial infarction (PZ.05) and hypertension (PZ.003) were predictive of CS inclusion. On multivariate analysis, only hypertension was a significant predictor (hazard ratio [HR] 0.6, 95% confidence interval [CI] 0.4-0.9, PZ.012). The Cancer of the Prostate Risk Assessment score showed a trend toward a higher score in patients not treated in a CS (HR 1.15, 95 %CI 0.98-1.32, PZ.09). Biochemical recurrence-free survival was similar between both groups with a 5-year rate of 94% in both groups (PZ.65). Conclusion: In our exploratory analysis, we found that patients treated in CSs did not differ from RLPs in terms of age, prostate cancer aggressiveness, or biochemical outcome. Patients with comorbidity were more often included in CSs. The impact on overall survival remains unclear. In our institution, conclusions from CS can be transferred to daily practice. Author Disclosure: D. Taussky: None. J. Bahary: None. C. Lambert: None. M. Beauchemin: None. G. Delouya: None. M. Barkati: None. X. Liem: None.

2606 Results of Scanning Beam Proton Therapy (SCBT) for the Treatment of Patients With High-Risk Prostate Cancer S. Choi,1 Q. Nguyen,1 T.J. Pugh,1 U. Mahmood,1 S.E. McGuire,2 K.E. Hoffman,1 S.J. Frank,1 D.A. Kuban,1 and A.K. Lee3; 1MD Anderson Cancer Center, Houston, TX, 2The University of Texas MD Anderson Cancer Center, Houston, TX, 3Texas Center for Proton Therapy, Irving, TX

E244

International Journal of Radiation Oncology  Biology  Physics

Purpose/Objective(s): To assess the outcomes of patients with high-risk prostate cancer who were treated with scanning beam proton beam radiation therapy (SBPT) and androgen deprivation therapy (ADT). Materials/Methods: We conducted a retrospective analysis of 64 patients with high-risk prostate cancer (stage T3a, Gleason 8, or PSA >20.0 ng/mL) who were treated with SBPT between July 2009 and February 2012. Patients were treated to their prostate and seminal vesicles with SBPT planned with single-field optimization (SFO). The median total radiation therapy dose was 78 Cobalt-Gray equivalent (CGE) in 2 CGE fractions (range 76-78 CGE). All patients were treated with daily image guidance with carbon fiducials, and an endorectal balloon was placed daily for immobilization of the prostate. All patients received ADT, usually starting 2 months before the start of the proton therapy. Patients were followed with prostatespecific antigen (PSA) measurements taken at 3- to 6-month intervals after SBPT. Biochemical failure was defined as nadir+2 as per the Phoenix definition. Genitourinary (GU) and gastrointestinal (GI) toxicity were defined using the modified Radiation Therapy Oncology Group (RTOG) scale. Results: Patient characteristics are listed in Table 1. The median age was 69 (range 45-89) years. Median follow-up was 41.5 (range 24-60) months. Fifty-two patients had current testosterone levels available; 42 patients (80.8%) had recovery of testosterone to >200 ng/dL (median 388, range 203-895). Two patients died without evidence of prostate cancer (at 44 and 51 months, respectively). There were 2 biochemical failures (at 32 and 45 months, respectively) for a freedom from biochemical failure (FFBF) rate of 96.9%. There were 6 patients with grade 1 and 12 with grade 2 GU toxicity (9.3% and 18.7%, respectively). Eleven of the 12 patients were graded as having grade 2 toxicity only because they were taking a medication to improve urination. There were 11 patients with grade 1 and 5 with grade 2 GI toxicity (17.2% and 7.8%, respectively). All of these patients had rectal bleeding, with 4 patients receiving 1 application of argon plasma coagulation. There was no grade 3 or higher GU or GI toxicity seen. Conclusion: Preliminary analysis of patients treated with scanning beam proton therapy and ADT shows encouraging results, with a high rate of cure and low risk of significant side effects.

Purpose/Objective(s): Significant racial disparity has been reported in prostate cancer including differences in risk, stage distribution, and pattern of care. This study aimed to report our clinical experience in order to examine the difference in overall survival (OS) between Caucasian and African American (AA) patients treated with different modalities, with consideration of other clinical factors. Materials/Methods: This single-institution retrospective analysis included prostate cancer patients in our tumor registry treated between 2002 and 2012. Age, gender, race, marital status, insurance status, stage, histology, tumor location, alcohol and smoking history, insurance information, and treatment modality were tested for their significance on OS. Cox proportional hazards model was utilized to determine differences in OS with time being 0 at diagnosis and ending with death or end of follow-up. The proportional hazards assumption was tested using Schoenfeld residuals. Results: A total of 1338 consecutive patients were included in this study; 769 (58%) were AA, the remaining (42%) were Caucasian. Median follow-up was 47 months. Univariate analysis demonstrated age at diagnosis, marital status, heavy alcohol use, smoking status, and stage were significantly associated with OS (P<.05). Race, insurance situation, and family history of cancer were not significant factors. Median survival was not significantly different between Caucasians and AAs (not reached for both groups). Compared with Caucasians, AA patients were more likely to be younger, unmarried, have later-stage disease at diagnosis, and were less likely to have private insurance and to receive surgery. The 5-year OS rates are 86.4% (82.9%-89.9%), 81.7% (95% CI: 78.5%-85.0%), for Caucasians and AAs, respectively. There was no significant difference in survival between these 2 groups for patients treated with surgery and radiation (P>.05). In Caucasians patients, only age and stage were factors significantly associated with OS (both P<.001), while in AA patients, age, smoking status, marriage status, and stage were all significant factors (all P<.001), after adjusting for other factors, such as insurance status. Conclusion: This study suggests no significant difference in OS, but differences in prognostic factors associated with survival between Caucasians and African Americans with prostate cancer. Smoking status and marriage status were not significant factors for survival for Caucasians, but they were significant factors associated with survival for African American patients. Author Disclosure: J. Campbell: None. J. Zhao: None. D. Zaenger: None. L. Colton: None. R. Madi: None. B.G. Dasher: None. C.L. Ferguson: None. R. Lewis: None. A. Smith: None. R. Sadek: None. M. Terris: None. F.P. Kong: None.

Poster Viewing Abstracts 2606; Table 1 Stage T1c-T2a T2b-T2c T3a T3b TX Gleason Score 7 (3+4, 4+3) 8 (4+4) 9 (4+5)

Number of Patients (%) 32 (50.0%) 18 (28.1%) 11 (17.2%) 2 (3.1%) 1 (1.6%)

12 (18.8%) 31 (48.4%) 21 (32.8%)

Patient Characteristics PSA

Number of Patients (%)

<4 ng/mL 4.0-10.0 ng/mL 10.1-20.0 ng/ mL >20 ng/mL ADT Duration 4 months

3 (4.7%) 36 (56.2%) 11 (17.2%)

6 months 12 months 24 months

6 (9.4%) 11 (17.2%) 45 (70.3%)

14 (21.9%) 2 (3.1%)

Author Disclosure: S. Choi: None. Q. Nguyen: None. T.J. Pugh: None. U. Mahmood: None. S.E. McGuire: None. K.E. Hoffman: None. S.J. Frank: None. D.A. Kuban: None. A.K. Lee: None.

2607 No Significant Difference in Overall Survival between Caucasian and African Americans Patient With Prostate Cancer: An Analysis of 1338 Patients From a Single Institution J. Campbell,1 J. Zhao,2 D. Zaenger,3 L. Colton,4 R. Madi,5 B.G. Dasher,5 C.L. Ferguson,5 R. Lewis,5 A. Smith,6 R. Sadek,1 M. Terris,5 and F.M.P. Kong5; 1GRU Cancer Research Center and Medical College of Georgia, Augusta, GA, 2GRU Cancer Center and Medical College of Georgia, Georgia Regents University, Augusta, GA, 3Mount Sinai Beth Israel Medical Center, New York, NY, 4GRU Cancer Center/Medical College of Georgia, Georgia Regents University, Augusta, GA, 5Georgia Regents University, Augusta, GA, 6Urology at Georgia Regents University, Augusta, GA

2608 Daily Dose Evaluation Utilizing In-Room Computed Tomography Positioning System for Prostate Cancer Treatment in Proton Therapy Y. Sato, Y. Maeda, H. Minami, Y. Yasukawa, K. Yamamoto, H. Tamamura, S. Shibata, S. Bou, M. Sasaki, Y. Tameshige, H. Ooto, S. Kasahara, Y. Shimizu, Y. Saga, A. Omoya, M. Saito, and M. Aoyama; Fukui Prefectural Hospital, Fukui, Japan Purpose/Objective(s): To evaluate dose changes due to the daily anatomical variations for prostate cancer treatment in proton radiation therapy based on the computed tomography (CT) images from an in-room CT positioning system. Materials/Methods: Since April 2014, more than 20 patients with prostate cancer have been treated with 78 GyE in 39 fractions or 74 GyE in 38 fractions with opposed lateral beams using an in-room CT positioning system in the Fukui proton therapy center. The patient body was repositioned by matching the prostate identified on in-room CT images to ones on simulator CT images after bone matching. Prostate, bladder, and rectum on all CT images were contoured by the radiation oncologist. The position shift of the prostate was evaluated based on the 3-dimensional coordinates of the centroid respect to the original CT image and were used to estimate the positioning uncertainty. Daily dose calculations were performed on all of the CT sets with the delivered dose of 2 GyE applying the original treatment planning to the daily isocenter. Dose-volume histograms (DVHs)