Overall survival after prostate-specific-antigen-detected recurrence following conformal radiation therapy

Purpose: To study the significance, in terms of overall and cause-specific survival, of biochemical failure after conformal external-beam radiation th erapy (RT) for prostate cancer. Methods and Materials: Of the 1844 patients in the Radiation Oncology prost ate cancer database, 718 were deemed eligible. Patients excluded were those with N1 or M1 disease, those treated after radical prostatectomy, those wh o received hormone therapy before radiation therapy, and those who died, fa iled clinically, or had no PSA response in the first 6 months after RT. Pat ients included were required to have a minimum of 2 post-RT PSAs separated by at least 1 week. Biochemical relapse was defined as 3 consecutive PSA ri ses. This resulted in 154 patients with biochemical failure. Survival was c alculated from the third PSA elevation. The rate of rise of PSA was calcula ted by fitting a regression line to the four rising PSAs on a In PSA vs, ti me plot. Results: There were 41 deaths among the 154 patients with failure in 23 of the 41 due to prostate cancer. The overall survival after failure was 58% a t 5 years, while the cause specific failure was 73% at 5 years. Among the 1 54 failures, several factors were evaluated for an association with overall survival: age at failure, pre-RT PSA, PSA at second rise, PSA nadir, time from RT to failure, time to nadir, Gleason score, T-stage, and rate of rise , both from the nadir and from the beginning of the rise. None of these fac tors were significantly associated with an increased risk of death. As expe cted, the group of patients nith biochemical failure have significantly wor se prognostic factors than those without biochemical failure: median pre-RT PSA 15.9 vs. 9.0 (p < 0.001), and Gleason score of 7 or greater for 48% of subjects vs. 40% (p = 0.1). Relative PSA rise and slope of In PSA vs. time were associated with cause-specific mortality (p < 0.001 and p = 0.007, re spectively). Conclusion: Overall survival after conformal radiotherapy for prostate canc er remains high 5 years after biochemical failure. This high survival rate occurs even though the group of patients with biochemical failure has worse than average adverse preradiation prognostic factors. Thus, although bioch emical failure can identify patients who have recurrent disease after RT, t he ultimate relationship between this endpoint and death remains to be bett er defined. (C) 2000 Elsevier Science Inc.