External beam radiation therapy improves survival in high- and intermediate-risk non-metastatic octogenarian prostate cancer patients

Purpose: There is no contemporary proof of cancer-control benefits in octogenarian clinically localized prostate cancer (PCa) patients with life expectancy (LE) < 10 years. Therefore, cancer-specific mortality (CSM) rates after external beam radiation therapy (EBRT) vs. no local treatment (NLT) were tested in octogenarian PCa patients with LE < 10 years. Methods: Within the surveillance, epidemiology, and end results database (2004–2015), we identified 22,361 octogenarian clinically localized PCa patients who either received EBRT or NLT. Temporal trends, cumulative incidence plots and multivariable competing-risks regression analyses (MCR) were used after propensity score matching. Sensitivity analyses were performed according to D’Amico risk groups and LE > 5 years. Results: Of all, 7325 (32.8%) received EBRT vs. 15,036 (67.2%) received NLT. Rates of EBRT significantly increased over time (25.0–42.4%). Overall, 10-year CSM rates were 10.6% vs. 17.0% and 10-year other-cause mortality rates were 50.3% vs. 58.1%, in EBRT vs. NLT patients (both p < 0.001). In MCR focusing on the overall cohort, EBRT represented an independent predictor of lower CSM (hazard ratio: 0.5). In sensitivity analyses, hazard ratios of 0.5 (p < 0.001), 0.5 (p < 0.001) and 0.8 (p = 0.5) were, respectively, recorded in D’Amico high-, intermediate- and low-risk patients. In sensitivity analyses addressing patients with LE > 5 years virtually the same results were recorded. Conclusions: In octogenarian patients with LE < 10 years, EBRT seems to be associated with lower CSM in D’Amico high-risk, as well as in D’Amico intermediate-risk patients relative to their NLT counterparts. Based on these observations, greater consideration for EBRT may be given in octogenarian patients.