Objectives: Serum acid phosphatase (ACP) was once used as the marker for advanced prostate cancer. However, with the development of assays for prostate-specific antigen (PSA), a more sensitive and specific tumor marker, the use of ACP has diminished. We investigated the prognostic value of preoperative serum ACP in predicting prognosis for men with localized prostate cancer following radical retropubic prostatectomy (RRP).
Methods: Of 2293 men treated from 1982 to 1998, 1681 men had a preoperative ACP measurement using an enzymatic assay. We analyzed the actuarial freedom from biochemical (PSA) progression following RRP according to ACP levels. We used multivariate logistic regression and proportional hazards models to determine the independent prognostic value of ACP level with respect of pathologic stage and biochemical recurrence.
Results: ACP was not an independent predictor of organ confinement or lymph node involvement in the multivariate logistic regression models using preoperative variables. However, in the proportional hazards model, ACP was an independent predictor of tumor recurrence following RRP, and there was a statistically significant improvement in biochemical recurrence-free survival for men with lower levels of ACP (P <0.001). Furthermore, the normalized hazard ratios of ACP and PSA for predicting biochemical recurrence were similar.
Conclusions: Stratification of men according to their preoperative ACP levels was predictive of patient outcome after RRP. Proportional hazards modeling using preoperative variables demonstrated that the serum ACP level is an independent predictor of tumor recurrence following RRP.