A subgroup analysis of treatment efficacy according to whether patients had low-, intermediate-, or high-risk disease, showed that the addition of short-term ADT to radiotherapy conferred the greatest clinical benefit in the intermediate-risk subgroup, with an increase in the 10-year rate of overall survival from 54 to 61% (hazard ratio for death with radiotherapy alone, 1.23; 95% CI, 1.02 to 1.49) and a reduction in the 10-year disease-specific mortality from 10 to 3% (hazard ratio, 2.49; 95% CI, 1.50 to 4.11). No significant benefit was shown in the low-risk subgroup, with an increase in the 10-year rate of overall survival from 64 to 67% (hazard ratio for death with radiotherapy alone, 1.07; 95% CI, 0.83 to 1.39) and an increase in the 10-year disease-specific mortality from 1 to 3% (hazard ratio, 0.63; 95% CI, 0.21 to 1.92). An interaction test revealed no significant interaction effect between treatment and risk category for overall survival (P = 0.71) and only a weak suggestion of a differential benefit according to risk group for disease-specific mortality (P = 0.08). In all three risk subgroups, short-term ADT was associated with a significant reduction in biochemical failure (Table 2). The incidence of positive findings on repeat prostate biopsy in the lowrisk, intermediate-risk, and high-risk subgroups was fairly uniform in the radiotherapy-alone group, at 35%, 41%, and 39%, respectively, as compared with 12%, 24%, and 30% in the combined-therapy group. Analyses of treatment efficacy separately in white and black patients and in patients who were 70 years of age or younger and those who were older than 70 years were also performed.

The addition of short-term ADT was associated with a benefit in all these subgroups, with the 10-year rate of overall survival increasing from 57 to 62% among white patients (hazard ratio for death with radiotherapy alone, 1.19), 55 to 61% among black patients (hazard ratio, 1.15), 64 to 70% among patients who were 70 years of age or younger (hazard ratio, 1.23), and 50 to 54% among those older than 70 years of age (hazard ratio, 1.11), with no statistical evidence of a differential benefit between whites and blacks (interaction test, P = 0.79) or between age subgroups (P = 0.47). Among black patients, the addition of shortterm ADT to radiotherapy was associated with a decrease in the 10-year disease-specific mortality from 7 to 5% (hazard ratio with radiotherapy alone, 1.27) and a decrease in the 10-year rate of biochemical failure from 40 to 19% (hazard ratio, 2.27).