Failing to achieve a nadir prostate-specific antigen after combined androgen blockade: Predictive factors

Objectives: To determine the optimal cut-off of a nadir prostate-specific antigen (PSA) for prediction of progression within 24 months after combined androgen blockade (CAB) and to analyze predictive factors of failing to achieve the nadir PSA. Methods: We retrospectively reviewed the medical records of 343 patients with prostate cancer treated with CAB from 2000 to 2005. We determined the nadir PSA level that predicts progression to hormone refractory prostate cancer (HRPC) at 24 months after CAB. Predictive factors for failing to achieve a determined nadir PSA were analyzed. Results: Mean age was 74.0 years. Mean follow up was 42.1 month. Seventy-seven patients experienced progression to HRPC. A nadir PSA of 1.0 ng/mL predicts progression to HRPC at 24 months. Predictive factors for failing to achieve a nadir PSA of 1.0 ng/mL or less include pretreatment PSA, percentage positive biopsy core, Gleason score, serum hemoglobin, stage, and extent of bone metastasis in univariate analysis. Pretreatment PSA (> 50 ng/mL) and serum hemoglobin (< 12 g/dL) were significant factors to predict failing to achieve a nadir PSA of 1.0 ng/mL or less in logistic regression analysis. Conclusions: A nadir PSA of 1.0 ng/mL can predict progression to HRPC after CAB. Pretreatment PSA and serum hemoglobin are significant predictors of failing to achieve a nadir PSA of 1.0 ng/mL or less.