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.