Other-cause mortality in incidental prostate cancer.

Background: In incidental prostate cancer (IPCa), elevated other-cause mortality (OCM) may obviate the need for active treatment. We tested OCM rates in IPCa according to treatment type and cancer grade and we hypothesized that OCM is significantly higher in not-actively-treated patients.

Methods: Within the Surveillance, Epidemiology, and End Results database (2004-2015), IPCa patients were identified. Smoothed cumulative incidence plots as well as multivariable competing risks regression models were fitted to address OCM after adjustment for cancer-specific mortality (CSM).

Results: Of 5121 IPCa patients, 3655 (71%) were not-actively-treated while 1466 (29%) were actively-treated. Incidental PCa not-actively-treated patients were older and exhibited higher proportion of Gleason sum (GS) 6 and clinical T1a stage. In smoothed cumulative incidence plots, 5-year OCM was 20% for not-actively-treated versus 8% for actively-treated patients. Conversely, 5-year CSM was 5% for not-actively-treated versus 4% for actively-treated patients. No active treatment was associated with 1.4-fold higher OCM, even after adjustment for age, cancer characteristics, and CSM. According to GS, OCM reached 16%, 27%, and 35% in GS 6, 7, and 8-10 not-actively-treated IPCa patients, respectively and exceeded CSM recorded for the same three groups (2%, 6%, and 28%, respectively).

Conclusion: Our results quantified OCM rates, confirming that in not-actively-treated IPCa patients OCM is indeed significantly higher than in their actively-treated counterparts (HR: 1.4). These observations validate the use of no active treatment in IPCa patients, in whom OCM greatly surpasses CSM (20% vs. 5%).