Propensity score matched analysis of metastasis-free survival for patients with high-risk prostate cancer treated with definitive radiation therapy or radical prostatectomy.

Abstract

47 Background: National Comprehensive Cancer Network (NCCN) category 1 recommendation for localized high risk prostate cancer (HR-PCa) is definitive radiation therapy (RT) and androgen deprivation therapy (ADT). Radical prostatectomy (RP) is also an accepted treatment for patients with localized HR-PCa. Here we report a propensity score-matched analysis of institutional outcomes for patients with HR-PCa treated with RP or RT. Methods: Medical recor ds of patients with localized NCCN HR-PCa treated at our institution from 2002-2011 were reviewed. RT consisted of 73.8-77.4 Gray to the prostate and seminal vesicles; regional lymph nodes were treated for pre-treatment probability of involvement ≥15%. A combination of nearest neighbor propensity score matching on age, Adult Comorbidity Evaluation-27 score [a validated comorbidity index], prostate specific antigen (PSA), biopsy Gleason, and clinical T-stage (cT) and exact matching on PSA, biopsy Gleason, and cT was performed. Multivariate cox-proportional hazards regression was used to compare metastasis-free survival (MFS) and overall survival (OS) (calculated from date of diagnosis). Results: 246 patients were identified (160 RP and 86 RT). Propensity score matching resulted in 62 matched pairs. For the RP group, minimally invasive surgery (70.9%) and lymph node dissection (100%) were common. ADT was administered to 37.1% and 80.6% of patients receiving RP and RT, respectively. Median follow-up was longer for the RT group (51.4 vs 41 months, p = 0.004). Five-year rates of metastasis for RT and RP were 8.9% and 33% (p = 0.003), and for death were 25.9% and 17.6%, respectively (p = 0.31). MFS was significantly better for patients treated with definitive RT compared to RP, while OS was not different (Table). Conclusions: In our cohort with HR-PCa, treatment with RT resulted in a MFS advantage over RP. This was not accompanied by an improvement in OS.The difference in MFS may possibly be related to the importance of early adjuvant ADT. [Table: see text]