Comparison of Radiation Therapy and Radical Prostatectomy in the Treatment of High-Risk Prostate Cancer: A Retrospective Matched Pair Review

Abstract

Both definitive radiation therapy (RT) ±androgen deprivation therapy (ADT) and radical prostatectomy (RP) + adjuvant RT±ADT are considered standard of care treatment regimens for patients with high risk prostate cancer. The ideal modality to treat this patient population and achieve disease control while also limiting treatment related toxicity remains debated. In this study, we utilized a retrospective matched pair analysis to compare survival and overall disease control outcomes relative to primary treatment modality. 1436 pts with National Comprehensive Cancer Network defined high risk prostate cancer diagnosed between August 1992 and October 2016 at a single institution were analyzed. All those eligible were treated with RP + adjuvant RT ±ADT (n=774) or definitive RT alone ±ADT (n=660), which consisted of either high dose rate (HDR) brachytherapy boost together with pelvic external beam RT (EBRT) or dose-escalated, adaptive radiation therapy (ART). A 1:1 matched pair analysis was completed, which paired 196 pts based on three poor prognostic characteristics: pre-treatment prostate-specific antigen (PSA) ≥ 20, Gleason score ≥ 8, and clinical T stage ≥T2c. There were 98 pts in both the RT and RP cohorts for this analysis. The average age of the RT and RP groups were 66.4 years and 66.7 years respectively. The median follow-up for those treated with RP was 13.6 years, while those treated with RT was 8.96 years. 21 (21.4%) treated with RP had ≥ T2c disease, while 37 (37.7%) treated with RT had ≥T2c disease. 40.8% in both the RP and RT cohorts had Gleason score ≥ 8. 37.8% of pts had a pre-treatment PSA ≥ 20 in both the RP and RT cohorts. 5 pts (5.1%) in both the RP and RT cohorts received ADT. 37 (37.7%) in the RT cohort were treated with HDR combined with EBRT, while 61 (62.2%) of the RT cohort were treated with ART. There was no statistical difference between pts treated with RT and those treated with RP for overall survival (p =0.21), cause specific survival (p=0.28), or distant disease control (p=0.88). RT was statistically superior compared to RP in regard to locoregional control (p=0.015). When analyzing the two modalities of RT used to treat high risk prostate cancer in this patient cohort compared to RP, both ART and HDR were statistically superior compared to RP in regard to locoregional disease control (p=0.049). Based on this retrospective matched pair analysis of 196 pts with high risk prostate cancer, the addition of radical prostatectomy to locoregional RT did not improve survival or locoregional disease control rates. Neither approach was associated with improved long-term survival, and locoregional disease control was superior in pts treated with definitive RT.