Prognostic role of serum prostatic acid phosphatase for Pd-103-based radiation for prostatic carcinoma

Purpose: To establish the prognostic role of serum enzymatic prostatic acid phosphatase (PAP) in patients treated with palladium (Pd-103) and suppleme ntal external beam irradiation (EBRT) for clinically localized, high-risk p rostate carcinoma. Methods and Materials: One hundred twenty-four consecutive patients with St age T2a-T3 prostatic carcinoma were treated from 1992 through 1995. Each pa tient had at least one of the following risk factors for extracapsular dise ase extension: Stage T2b or greater (100 patients), Gleason score 7-10 (40 patients), pretreatment prostate specific antigen (PSA) > 15 ng/ml (32 pati ents), or elevated serum PAP (25 patients). Patients received 41 Gy conform al EBRT to a limited pelvic field, followed 4 weeks later by a Pd-103 boost (prescription dose 80 Gy). Biochemical failure was defined as a PSA greate r than 1 ng/ml (normal < 4 ng/ml). Results: The overall, actuarial freedom from biochemical failure at 4 years after treatment was 79%. In Cox-proportional hazard multivariate analysis, the strongest predictor of failure was elevated pretreatment acid phosphat ase (p = 0.02), followed by Gleason score (p = 0.1), and PSA (p = 0.14). Conclusion: PAP was the strongest predictor of long-term biochemical failur e. It may be a more accurate indicator of micrometastatic disease than PSA, and as such, we suggest that it be reconsidered for general use in radiati on-treated patients. (C) 1999 Elsevier Science Inc.