Freedom from castration: an alternative end point for men with localized prostate cancer treated by external beam radiation therapy.

Abstract

Androgen deprivation therapy (ADT) is frequently given to men with localized prostate cancer. This study was designed to determine what proportion of men require subsequent ADT if their localized prostate cancer is first treated by radiation. A retrospective review of the outcome of 768 men with T1-4NxM0 prostate cancer treated with external beam radiation at a single institution from 1988 to 1995. The median follow-up for the entire group was 5.8 years. The end points analyzed were biochemical failure (3 successive rises in prostate-specific antigen) and ADT (either medical or surgical castration). A total of 322 biochemical failure events occurred among the 768 treated patients, and 187 began ADT during the period of observation. Fifty-four percent of men starting ADT did so without rebiopsy or radiographic evidence of persistent disease. The overall freedom from biochemical failure rate at 10 years was 43.3% and the 10-year freedom from ADT rate was 56.3%. The corresponding values for the most favorable subgroup (T1-2a, Gleason sum 6, prostate-specific antigen <or=10 ng/mL) were 61.8% and 72.8%. Curative therapy is often given to men with prostate cancer and a life expectancy of <10 years, even when a survival gain is not expected. One new measure of its value, if any, may be its efficacy in preventing a subsequent, potentially more morbid, therapy such as ADT. The results of this study showed that most men with early-stage prostate cancer do avoid ADT in the 10 years after radiation therapy. This rate is less than that seen in the few contemporary watchful-waiting series.