Age-race interaction in prostatic adenocarcinoma treated with external beam irradiation

The most important predictors of long-term survival in patients with adenocarcinoma of the prostate are histological grade and stage of disease. However, the role of other epidemiological factors, particularly age and race, remains controversial. There is a school of thought that black patients and younger patients have a biologically more aggressive disease. We analyzed the survival of 914 patients (867 whites and 47 blacks) with localized adenocarcinoma of the prostate treated with external beam irradiation from the Connecticut SEER Tumor Registry data base. Patients were treated from 1973-1987, and those with Stages A1, A2 and D2 were excluded. Patients < or = 60 years of age had a 5-year survival rate of 72% compared to 61% for those > 60 years of age (p = 0.06). When stratified by race, white patients had a 63% 5-year survival rate versus 47% in black patients (p = 0.02). When analyzed by race and age, and age-race interaction was noted. Although younger whites fared better than older whites, 77% versus 61% survival at 5 years (p = 0.02), younger blacks fared worse than older blacks, 31% versus 52% survival at 5 years (p = 0.21). Blacks, on average, presented at an earlier age than whites, 65 years versus 69 years (p = 0.001). Both races had similar stage and similar grade of disease. In older patients, both races presented with similar stage and grade of disease and had similar survival. However, in the younger age group, black patients presented with similar grade, but higher stage disease than whites. This may explain the worse survival in young blacks compared to young whites, 31% versus 77% at 5 years (p = 0.007). Multivariate analysis revealed that, even controlling for stage and grade, blacks still fared worse than whites. Increased age was associated with decreased survival in whites but increased survival in blacks.