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

Abstract

Purpose: To establish the prognostic role of serum enzymatic prostatic acid phosphatase (PAP) in patients treated with palladium ( 103Pd) and supplemental external beam irradiation (EBRT) for clinically localized, high-risk prostate carcinoma. Methods and Materials: One hundred twenty-four consecutive patients with Stage T2a–T3 prostatic carcinoma were treated from 1992 through 1995. Each patient had at least one of the following risk factors for extracapsular disease extension: Stage T2b or greater (100 patients), Gleason score 7–10 (40 patients), pretreatment prostate specific antigen (PSA) > 15 ng/ml (32 patients), or elevated serum PAP (25 patients). Patients received 41 Gy conformal EBRT to a limited pelvic field, followed 4 weeks later by a 103Pd boost (prescription dose 80 Gy). Biochemical failure was defined as a PSA greater 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 phosphatase ( 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 failure. 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 radiation-treated patients.