Cause-specific mortality of low and selective intermediate-risk prostate cancer patients with active surveillance or watchful waiting

BACKGROUND: Active surveillance or watchful waiting (AS/WW) is increasingly being used as an alternative strategy to radical prostatectomy or radiation therapy for appropriately selected patients with prostate cancer (PCa). However, the prognosis of low-risk and selective intermediate-risk PCa patients after AS/WW is poorly defined. In this study we reviewed the patients registered in the Surveillance, Epidemiology, and End Results (SEER) Program to establish a competing risk nomogram for the prediction of prostate cancer-specific mortality (PCSM). METHODS: The information of patients undergoing AS/WW in the SEER program from 2004 to 2015 was obtained. All patients were ISUP (International Society of Urological Pathology) grade 1 or 2 PCa and also fulfilled the National Comprehensive Cancer Network’s definition of low-risk PCa [prostate specific antigen (PSA) <10 ng/mL and cT2aN0M0 or less)]. A competing risk nomogram was used to analyze the association of tumor characteristics with PCSM and non-PCSM among the PCa patients with AS/WW. All cases were randomly divided into a training cohort and a validation cohort (1:1). A competing risk nomogram was constructed to predict PCSM in PCa patients with AS/WW. The performance of the PCSM nomogram was evaluated using the concordance index (C-index) and calibration curve. RESULTS: A total of 30,538 PCa patients were identified as low risk or selective intermediate risk with AS/WW. The 10-year cumulative incidence of death from prostate cancer and death from other cause were 2.8% (95% CI: 2.4–3.1%) and 19.3% (95% CI: 17.8–20.5%), respectively. Variables associated with PCSM included age, marital status, PSA, and ISUP grade. The PCSM nomogram had a good performance in both the training and validation cohorts, with a C-index of 0.744 (95% CI: 0.700–0.781, P<0.001) and 0.738 (95% CI: 0.700–0.777, P<0.001), respectively. CONCLUSIONS: Overall, the prognosis was favorable for the low- and selective intermediate-risk PCa patients with AS/WW. The competing risk nomogram yielded a good performance in identifying subgroups of patients with a higher risk of PCSM and potential candidates for AS/WW.