10-year outcome for men with localized prostate cancer treated with external radiation therapy: results of a cohort study.

PURPOSE: We determine the efficacy of conventional dose, external beam radiation for localized prostate cancer using cohort analysis with maximized followup.
MATERIALS AND METHODS: A total of 205 men with T1-2 prostate cancer were treated with conventional external beam radiation to a median and modal dose of 68.4 Gy during a 16-month period from 1991 to 1993. Followup was maximized in these patients, and median followup for those alive with or without disease was 114 months.
RESULTS: Median patient age at treatment was 72 years, and overall survival at 5 and 10 years was 78% and 53%, respectively. The actuarial risk of local failure was 18% at 10 years as was the risk of metastatic disease. The actuarial risk of being free of biochemical failure at 10 years (American Society for Therapeutic Radiology and Oncology definition) was 49%. That risk was 42% if the definition was used without backdating failure to a time between last low value and first increase. When a crude analysis of 10-year outcome was performed 127 of the 205 treated patients (62%) were still alive, including 59% with no evidence of biochemical failure and a median prostate specific antigen of 1.0 ng/ml. Of the 78 men (38% of total) who died during the 10 years 32 died either of or with recurrent cancer.
CONCLUSIONS: Mature followup minimizes many of the biases seen in previously published radiation series. This study provides a yardstick against which newer radiation modalities may be measured.