MP62-14 LONG-TERM RESULTS OF POST-PROSTATECTOMY RADIOTHERAPY: A LARGE INSTITUTIONAL EXPERIENCE

THE JOURNAL OF UROLOGYâ

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observed in larger prostate volumes when analysed by size quartiles (p¼0.02). Multivariate analysis of pre-treatment variables showed large prostate volume to be the only predictor of BRFS (HR¼0.60 per 10mls increase in size, p¼0.026). With the inclusion of post-treatment data (ie. PSA nadir, time to PSA, D90 and V100), independent predictors of BRFS were prostate volume (HR¼0.50, p¼0.024), PSA nadir (p¼0.003) and time to nadir (p<0.001). History of bladder outflow surgery did not predict BRFS. A high pre-treatment PSA was the only pre-operative and post-operative predictor of grade III toxicity (HR¼1.26, p¼0.01). CONCLUSIONS: Large prostate size is an independent predictor of favourable biochemical outcome after LDRB. PBOS did not affect BRFS nor increase the incidence of grade III toxicity and hence is not a reason to deny LDRB. Source of Funding: None

MP62-14 LONG-TERM RESULTS OF POST-PROSTATECTOMY RADIOTHERAPY: A LARGE INSTITUTIONAL EXPERIENCE Rebecca Clayman*, Adam Feldman, Sigolene Galland, Douglas Dahl, Francis McGovern, Aria Olumi, Alec Eidelman, Andrzej Niemierko, William Shipley, Anthony Zietman, Jason Efstathiou, Boston, MA INTRODUCTION AND OBJECTIVES: Randomized trials and consensus statements support the consideration of adjuvant radiation therapy (RT) following prostatectomy for adverse pathologic features (pT3 or positive margins) although its use remains low. Whether early salvage RT is as effective as immediate adjuvant therapy remains unknown. METHODS: A retrospective single institutional analysis of 728 post-prostatectomy patients receiving RT between 1993 and 2012 was performed. Early salvage RT was defined as radiation received for a biochemical recurrence with postoperative PSA 0.5ng/ml. A Cox regression multivariable analysis (MVA) was used to identify clinical and treatment-related risk factors associated with biochemical recurrencefree survival, freedom from salvage androgen deprivation therapy (ADT), distant metastasis (DM), and overall survival (OS). RESULTS: 187 patients were treated with adjuvant RT for adverse pathologic features, while 541 patients received salvage RT (184 of whom received early salvage and had initial pT3 disease and/or positive margins). Median follow-up from surgery was 7.0 and 8.9 years in the adjuvant and salvage cohorts, respectively. Median time from surgery to adjuvant RT was 4.5 months, and median time to first detectable PSA in the salvage cohort was 1.98 years (Range 0.014e15.4 years). In MVA, higher Gleason score, pT-stage, seminal vesicle involvement, and shorter interval between surgery and first detectable PSA were associated with increased risk of biochemical failure, DM, and subsequent need for ADT. Younger age (P<0.0001), lower pre-op PSA (p¼0.005), and longer interval between surgery and first detectable PSA (P¼0.007) were associated with increased OS. When compared to early salvage, adjuvant RT was associated with significantly improved 10-year freedom from biochemical failure (73.9% vs 59.5%, HR 0.60 (95%CI: 0.4-0.9), P¼0.01); however there were no statistically significant differences in terms of 10-yr freedom from ADT (91.2% vs 83.2%, HR 0.67 (95%CI: 0.36-1.2), P¼0.2), DM (95.8% vs 91.8%, HR 0.86 (95%CI: 0.3-2.2), P¼0.8), and OS (97.8% vs 95.2%, HR 1.7 (95%CI: 0.6-4.6), P¼0.3). CONCLUSIONS: Postoperative RT confers excellent long-term disease control, a finding validated by the long follow-up in this series. Adjuvant RT is associated with reduced risk of PSA recurrence though not DM, OS, or need for subsequent ADT when compared to early salvage. Rational optimal timing of postoperative RT awaits report of the results of large ongoing randomized trials. Source of Funding: None

Vol. 193, No. 4S, Supplement, Monday, May 18, 2015

MP62-15 YOUNG AGE PREDICTS FOR TRANSIENT ELEVATION IN PSA AFTER DEFINITIVE STEREOTACTIC BODY RADIATION THERAPY FOR PROSTATE CANCER Seth Blacksburg*, Matthew Witten, Aaron Katz, Jonathan Haas, Mineola, NY INTRODUCTION AND OBJECTIVES: Stereotactic Body Radiation Therapy (SBRT) is a standard therapeutic option for men with prostate adenocarcinoma. There is a small body of literature characterizing a PSA bump after treatment with SBRT. Despite this, there is a paucity of data addressing rates of transient PSA increase immediately after SBRT treatment and what factors portend for this rare occurrence. This study reports outcomes on initial PSA after SBRT therapy for men who have undergone definitive radiation for prostate cancer. METHODS: Between May 2006 and February 2014, 921 patients with prostate cancer were treated with SBRT delivered via Cyberknife robotic-based therapy. The mean age was 67 years old. 68.5% of patients were Caucasian, 17.4% African American, and 14.1% were another ethnicity. Patients were divided into prognostic risk groups with 44.7%, 43.5%, and 11.1% of patients falling in the low, intermediate, and high risk stratifications. Gleason scores were < 6 in 44.4%, 7 in 41.3%, and 8-10 in 14.2%. 37 patients also received supplemental external beam radiation (median dose 4500cGy) and 8.9% of patients received Androgen Deprivation Therapy (ADT) as part of their treatment regimen. Pre-treatment PSA was 0.8 e 205 ng/ml (median 6.1). RESULTS: At three months’ follow-up, 2.8% of patients had a PSA elevated above their baseline value. 27.8% of patients age 50 (p<.0001) and 8.4% of patients age 60 (p¼.001) experienced an increased in baseline PSA. African Americans were more likely to experience a transient increase in PSA over Caucasians (7.8% vs. 3.0%, p¼.06). Patients treated with fewer beams were also more likely have a temporary rise in PSA (p¼.056). Gleason Score, Risk grouping, prostate volume, ADT, and EBRT did not predict for rise on Pearson Chi-Square analysis. On multivariate analysis, only age 50 (p<.0001) portended for increased PSA at 3 months’ time. CONCLUSIONS: This represents the largest series evaluating elevation of PSA after definitive SBRT for prostate cancer. Temporary rise in baseline PSA after SBRT is a rare occurrence. Despite that, a significant cohort of younger patients can experience transient elevation, which can cause patient and physician unease. Patient age 50 was found to be the only predictor of this otherwise rare occurrence. Source of Funding: none

MP62-16 FACTORS AFFECTING METASTASIS AND LONG-TERM SURVIVAL FOLLOWING PROSTATE BRACHYTHERAPY Nelson Stone*, Richard Stock, New York, NY INTRODUCTION AND OBJECTIVES: To determine the prognostic and treatment related variables associated with metastases and decreased cause specific survival (CSS) following prostate brachytherapy. METHODS: 1669 men with T1-T3 prostate cancer were followed a minimum of 5 years and treated with implant alone (683, 40.9%), implant plus external beam irradiation (EBRT, 88, 5.3%), implant plus hormone therapy (HT, 417, 25%) or implant plus HT and EBRT (481, 28.9%). 898 (53.8%) were treated with a median of 6 months of HT (range 1-34). Median patient age was 66 years and mean PSA 9.7 ng/ml. There were 757 (45.5%) patients at low, 642 (38.5%) intermediate and 267 (16%) high risk. Radiation dose was converted to the biological equivalent dose (BED) and was a median of 198 Gy2. Patients were followed a mean of 9.2 years (median 8.8, range 5-21). Men were diagnosed with metastatic disease (Metz) had a positive