Radiation after radical prostatectomy in elderly patients - a SEER database-derived competing-risk survival analysis of propensity score-matched age groups.

Introduction: This study aimed to evaluate cancer-specific (CSM) and other-cause mortality (OCM) in elderly patients with prostate cancer treated with radical prostatectomy (RP) and postoperative radiotherapy (RT).

Material and methods: The Surveillance, Epidemiology, and End Results (SEER) database was searched for clinically non-metastatic prostate cancer (PCa) treated with RT after RP between 2010 and 2015. Patients were stratified according to age groups and underwent propensity score (PS) matching. The Kaplan-Meier method and competing-risk Cox regression (CRR) were used for survival analysis.

Results: In total, 5385 patients were analysed, including 738 (13.7%) elderly patients (≥70 years old) and 4647 (86.29%) younger individuals. A total of 54 (7.32%) and 69 (9.35%) patients aged ≥70 years died due to PCa and competing reasons, respectively. Among younger patients these included 275 (5.92%) and 208 (4.48%) deaths, respectively. At a median follow-up of 80 months, patients ≥70 years old had significantly shorter OCM (p <0.0001) than PS-matched younger controls without significant impairment of cancer-specific survival when compared to controls (p = 0.19). In CRR analysis older patients were at significantly higher risk of OCM (HR = 2.24, p = 0.0002 and HR = 3.3, p = 0.011 for patients aged ≥70 and ≥75 years, respectively). Simultaneously, the CRR revealed no increased risk of CSM for patients older than 70 and 75 years (HR = 1.2, p = 0.33 and HR = 1.53, p = 0.29, respectively).

Conclusions: Elderly patients with PCa are at high risk of dying due to competing reasons, which might prevent the survival benefit of RT after RP. Selection for salvage and adjuvant RT in these individuals should be cautious.