A Competing Risk Analysis of Cancer-Specific Mortality of Initial Treatment with Radical Prostatectomy versus Radiation Therapy in Clinically Localized High-Risk Prostate Cancer

Abstract

BACKGROUND: There is no consensus on the optimal treatment for localized high-risk prostate cancer (PC), and much debate exists regarding the ideal treatment approach. For these reasons, we evaluated the competing risks of PC-specific mortality after initial therapy with radical prostatectomy (RP) versus radiotherapy (RT) in men with clinically localized high-risk PC. METHODS: We reviewed patients treated with RP and RT combined with androgen-deprivation therapy between 1990 and 2009. High-risk PC is defined as clinical stage ≥T3a, serum prostate-specific antigen (PSA) >20 ng/mL, or a biopsy Gleason sum of 8-10 according to National Comprehensive Cancer Network guidelines. Competing risk analysis was conducted to assess the association of RP (n = 251) or RT (n = 125) with cancer-specific mortality (CSM). Thereafter, secondary analysis with propensity score matching was conducted to further elucidate patient characteristics, with optimal matching of 0.25 times the standard deviation of propensity scores. RESULTS: With an overall median follow-up of 76 months, 35 (9.3 %) men with high-risk PC died due to PC (23 in the RT group and 12 in the RP group). The 5-year estimates of cancer-specific survival rate for men treated with RP and RT were 96.5 % (95 % confidence interval [CI] 94.2-98.9) and 88.3 % (95 % CI 82.8-94.3), respectively. Cumulative incidence estimates for CSM were statistically increased amongst men treated with RT (p = 0.002). Propensity score matching extracted 168 men with high-risk PC from the total patient cohort. Cumulative incidence estimates for CSM were statistically different amongst men treated with RT (p < 0.001).