Survival outcomes of radical prostatectomy vs. external beam radiation therapy in prostate cancer patients with Gleason Score 9-10 at biopsy: A population-based analysis

Purpose: Gleason Score (GS) 9-10 prostate cancer is associated with particularly adverse oncological outcomes and the optimal treatment is unknown. Therefore, cancer-specific mortality (CSM) rates after radical prostatectomy (RP) ± adjuvant radiation therapy (aRT) vs. external beam radiation therapy (EBRT) were tested. Methods: Within the Surveillance, Epidemiology, and End Results database (2004–2015), 17,897 clinically localized prostate cancer patients with biopsy GS 9-10 were identified who either received RP ± aRT or EBRT. Temporal trends, cumulative incidence plots and multivariable competing-risks regression analyses were used after propensity score matching. Sensitivity analyses were performed according to primary treatment type (RP only vs. EBRT). Results: Of all, 8,890 (49.7%) underwent EBRT vs. 9,007 (50.3%) underwent RP. Of those, 2,584 (28.7%) received aRT. No significant change in treatment assignment was recorded over time. In cumulative incidence smoothed plots, 10 year CSM rates were 19.9% vs. 19.6% (P = 0.3) and 10 year other-cause mortalityrates were 11.5% vs. 31.2%, respectively, in RP vs. EBRT patients (P < 0.001). In multivariable competing-risks regression analyses, RP did not reach independent predictor status of lower CSM (hazard ratio (HR): 0.93, P = 0.2). In sensitivity analyses within RP only vs. EBRT patients, RP represented an independent predictor of lower CSM (HR: 0.76, P < 0.001). Conclusions: In biopsy GS 9-10 patients, no CSM differences were observed after RP ± aRT vs. EBRT. However, in patients in whom RP did not have to be combined with aRT, RP seems to be associated with a minor improvement in cancer-specific survival compared to EBRT. This applied to the majority of GS 9-10 RP patients.