Competing Risks of Mortality among Men with Biochemical Recurrence after Radical Prostatectomy

PURPOSE: Men with biochemical recurrence after radical prostatectomy need information on competing risks of mortality to inform prognosis and guide treatment. We quantified the risk of prostate cancer metastasis and mortality, and other cause mortality across key clinical predictors. MATERIALS AND METHODS: We analyzed 1,225 men with biochemical recurrence after radical prostatectomy from 2001 to 2017 in the VA SEARCH database. Multivariable competing risks regression was used to identify predictors and quantify cumulative incidence of metastasis, prostate cancer specific mortality and other cause mortality. Recursive partitioning analysis was used to identify optimum variable cut points for prediction of prostate cancer specific mortality and other cause mortality. RESULTS: During a median followup of 5.6 years after biochemical recurrence (IQR 2.7-9.1), 243 (20%) men died of other causes and 68 (6%) died of prostate cancer. Multivariable competing risks regression showed that high D'Amico tumor risk and prostate specific antigen doubling time at biochemical recurrence less than 9 months were associated with metastasis and prostate cancer specific mortality (p ≤0.001). Ten-year prostate cancer specific mortality was 14% and 9% for those with high risk tumors and prostate specific antigen doubling time less than 9 months, respectively. Advanced age and worse comorbidity were associated with other cause mortality (p ≤0.001). Ten-year other cause mortality was higher among men 70 years old or older with any Charlson comorbidity (1-3+) (40% to 49%) compared to those with none (20%). Recursive partitioning analysis identified optimal variable cut points for prediction of prostate cancer specific mortality and other cause mortality, with 10-year prostate cancer specific mortality ranging from 3% to 59% and 10-year other cause mortality ranging from 17% to 50% across risk subgroups. CONCLUSIONS: Among men with biochemical recurrence after radical prostatectomy, there is significant heterogeneity in prognosis that can be explained by available clinical variables. Men in their 70s with any major comorbidity are 2 to 10 times more likely to die of other causes than of prostate cancer.