Survival After Conservative Management Versus External Beam Radiation Therapy in Elderly Patients With Localized Prostate Cancer

PURPOSE: To compare survival in elderly men with clinically localized prostate cancer (PCa) according to treatment type, defined as radiation therapy (RT) with or without androgen deprivation therapy (ADT) versus conservative management (observation).

METHODS AND MATERIALS: In the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database, we identified 23,790 patients aged 80 years or more with clinically localized PCa treated with either RT or observation between 1991 and 2009. Competing risks analyses focused on cancer-specific mortality and other-cause mortality, after accounting for confounders. All analyses were repeated after stratification according to grade (well-differentiated vs moderately differentiated vs poorly differentiated disease), race, and United States region, in patients with no comorbidities and in patients with at least 1 comorbidity. Analyses were repeated within most contemporary patients, namely those treated between 2001 and 2009.

RESULTS: Radiation therapy was associated with more favorable cancer-specific mortality rates than observation in patients with moderately differentiated disease (hazard ratio [HR] 0.79; 95% confidence interval [CI] 0.66-0.94; P=.009) and in patients with poorly differentiated disease (HR 0.58; 95% CI 0.49-0.69; P<.001). Conversely, the benefit of RT was not observed in well-differentiated disease. The benefit of RT was confirmed in black men (HR 0.54; 95% CI 0.35-0.83; P=.004), across all United States regions (all P≤.004), in the subgroups of the healthiest patients (HR 0.67; 95% CI 0.57-0.78; P<.001), in patients with at least 1 comorbidity (HR 0.69; 95% CI 0.56-0.83; P<.001), and in most contemporary patients (HR 0.55; 95% CI 0.46-0.66; P<.001).

CONCLUSIONS: Radiation therapy seems to be associated with a reduction in the risk of death from PCa relative to observation in elderly patients with clinically localized PCa, except for those with well-differentiated disease.