External Beam Radiation Therapy With a Brachytherapy Boost Versus Radical Prostatectomy in Gleason Pattern 5 Prostate Cancer: A Population-Based Cohort Study

Purpose Patients with prostate cancer (PCa) containing Gleason pattern (GP) 5 disease experience a greater and earlier incidence of prostate cancer-specific mortality (PCSM) than general PCa patients. This affords the statistical power to compare PCSM outcomes among different treatment modalities even when restricting the analysis to patients treated in the modern era. The purpose of the present study was to compare the survival outcomes among patients with GP 5 PCa on needle core biopsy or transurethral resection of the prostate who underwent extremely dose-escalated radiation therapy (RT; exemplified by external beam RT with a brachytherapy boost [EBRT + BT]) versus radical prostatectomy (RP) in the modern era. Methods and Materials A total of 7669 men with a diagnosis of GP 5 PCa from 2004 to 2013 who had undergone EBRT + BT or RP were identified using the Surveillance, Epidemiology, and End Results database. After propensity score matching to balance the patient characteristics, PCSM was compared between modalities using a multivariate Fine and Gray competing risk model that accounted for other-cause mortality, with adjustment for age, race, GP, and clinical T stage. Results Patients treated with RP were younger and had a lower burden of GP 5, lower T stage, and lower other-cause mortality than patients who underwent EBRT + BT. After propensity score matching, no difference was found in PCSM between the RP and EBRT + BT groups (adjusted hazard ratio 1.018; P=.910). The cumulative 5-year PCSM incidence rates were 5.6% and 6.1% for patients undergoing RP and EBRT + BT, respectively. Patients with primary GP 5 experienced significantly greater PCSM than those with secondary GP 5, regardless of the treatment modality. Conclusions For patients with GP 5 PCa found on needle core biopsy or transurethral resection of the prostate, RP and EBRT + BT offer equivalent PCSM in a competing risk model after propensity score matching to balance the differences in patient characteristics.