Statistical Analysis
On the basis of previous studies, we expected patients treated with radiotherapy alone to have an 8-year overall survival rate of 60%. Adding short-term ADT was projected to increase this rate to at least 67%. Accordingly, the trial was designed to provide 90% power to detect a 7-percentage-point absolute difference in the 8-year survival rate, with the use of a one-sided log-rank test at the 0.025 significance level, requiring 1980 patients and 716 deaths for definitive analysis. We conducted three planned interim analyses with a significance level of P<0.001 as the criterion for early stopping, which was not met in any of these analyses. The primary end point, overall survival, was estimated by means of the Kaplan–Meier approach, and in the multivariate analyses, hazard ratios with 95% confidence intervals were estimated
with the use of the Cox regression model.

The end points of disease-specific mortality, distant metastases, and biochemical failure were estimated by means of the cumulative incidence function to account for competing risks. The Fine–Gray model was used to estimate hazard ratios for competing risks. The chi-square test was used to test differences in patients’ responses to the Sexual Adjustment Questionnaire. Three subgroup analyses of treatment efficacy were conducted. One was planned: a comparison of treatments within racial groups (white and black). Two were unplanned; one compared treatments within three risk categories defined according to baseline characteristics, and the other evaluated treatments within two age groups (≤70 years and >70 years). The likelihood-ratio test was used to assess whether there was a statistically significant difference in the magnitude of treatment benefit (i.e., interaction effect) according to patient subgroups.

Characteristics of the Patients
Between October 1994 and April 2001, a total of 2028 patients from 212 centers in the United States and Canada were randomly assigned to radiotherapy plus short-term ADT (the combined-therapy group) or radiotherapy alone. Forty-nine patients were ineligible, withdrew consent, or were lacking pretreatment data, leaving 1979 eligible patients who were available for evaluation (992 in the radiotherapy-alone group and 987 in the combined- therapy group).

Compliance
Compliance with the radiotherapy protocol was assessed in a random sample of 61% of the patients in the combined-therapy group and 64% in the radiotherapy-alone group. Compliance was balanced between the two treatment groups; 65% of the patients were treated per protocol, 19% were treated with acceptable variations, and 5% were treated with unacceptable variations. Data were incomplete in 1% of the patients because of death or progressive disease or because the patient declined radiotherapy, and 9% were not available for evaluation. Compliance with hormonal therapy was reviewed in all randomly assigned patients; the therapy was delivered per protocol in 78% of the patients, with acceptable variation in 17% and unacceptable deviation in 4%. Data were incomplete or were not available for evaluation in 1% of these patients.

Outcomes
The median follow-up for surviving patients was 9.1 years (range, 0.01 to 13.5) in the group of patients who received radiotherapy plus short-term ADT and 9.2 years (range, 0.2 to 14.1) in the group of patients who received radiotherapy alone. The 10-year rate of overall survival was 57% in the radiotherapy-alone group and 62% in the combined-therapy group (hazard ratio for death with radiotherapy alone, 1.17; 95% confidence interval [CI], 1.01 to 1.35; P = 0.03). The 10-year disease-specific mortality was 8% in the radiotherapy-alone group and 4% in the combined-therapy group (hazard ratio, 1.87; 95% CI, 1.27 to 2.74; P = 0.001). The 10-year rate of biochemical failure was 41% in the radiotherapy-alone group and 26% in the combined-therapy group (hazard ratio, 1.74; 95% CI, 1.48 to 2.04; P<0.001). The 10-year cumulative incidence of distant metastases was 8% in the radiotherapy-alone group and 6% in the combined-therapy group (hazard ratio, 1.45; 95% CI, 1.03 to 2.06; P = 0.04). The 10-year cumulative incidence of death from causes other than prostate cancer was 37% in the radiotherapy-alone group and 34% in the combined-therapy group (P = 0.56).