Cancer-specific mortality after radical prostatectomy versus radiotherapy in incidental prostate cancer.

Introduction: To test for cancer specific mortality (CSM) differences after either radical prostatectomy (RP) or radiotherapy (RT) in incidental prostate cancer (IPCa) patients.

Patients And Methods: Within the Surveillance, Epidemiology, and End Results (SEER) database (2004-2015), IPCa patients were identified. Cumulative incidence plots as well as competing risks regression (CRR) models were fitted to address CSM after adjustment for other-cause mortality (OCM). Furthermore, a subgroup analysis was performed to test for CSM differences between RP and RT according to Gleason sum (GS 6,7, and 8-10).

Results: Of 1,466 IPCa patients, 770 (53%) underwent RP vs. 696 (47%) RT. Incidental PCa RT patients were older, and exhibited higher PSA, higher proportion of Gleason sum 8-10, and higher clinical T stage. In cumulative incidence plots, 5-year CSM rates adjusted for OCM were 0.9 for RP vs. 6.8% for RT (Δ = 5.9%). After multivariable adjustment for clinical characteristics (age, PSA, Gleason sum, and clinical T stage) as well as for OCM, RP was associated with a protective hazard ratio (HR) of 0.35 (95% confidence interval [CI] 0.15 - 0.78, p value = .01). Within Gleason sum 8-10 IPCA patients, RP was associated with a protective HR of 0.31 (P = .039).

Conclusion: Incidental PCa RT-treated patients exhibited less favorable clinical characteristics than their RP counterparts. Despite full adjustment, RP was associated with a protective effect relative to RT. This effect exclusively applied to the Gleason sum 8-10 subgroup. In consequence, IPCa patients harboring Gleason sum 8-10 should ideally be considered for RP instead of RT.