Serum alkaline phosphatase differentiates prostate-specific antigen flare from early disease progression after docetaxel chemotherapy in castration-resistant prostate cancer with bone metastasis

Abstract

PURPOSE: A transient rise in prostate-specific antigen (PSA) after the initiation of chemotherapy, called as PSA flare, has been frequently reported in patients with castration-resistant prostate cancer (CRPC) but there has been no way to differentiate PSA rises in CRPC. We investigated whether bone-related serum markers differentiate PSA flare from progression in CRPC patients with bone metastasis. METHODS: We reviewed CRPC patients with bone metastasis who received systemic chemotherapy from 2002 to 2008. Pretreatment baseline and follow-up data including age, performance score, PSA, Gleason score, alkaline phosphatase (ALP), calcium level, and hemoglobin were evaluated. Pretreatment parameters and follow-up serum parameters after the first cycle of chemotherapy were included in statistical analyses. RESULTS: PSA increased in 38 patients (45.8 %) at the first evaluation after chemotherapy. Among the PSA rises, PSA increased continuously or did not decrease to the stabilization level by the third evaluation in 22 (26.5 %) patients, while PSA decreased to the stabilization or response level by the third evaluation in 16 (19.3 %). PSA flare occurred in 17 (20.5 %). The univariate analyses showed that no baseline parameters were associated with PSA flare, but the initial ALP decrease, changed ALP ratio, and median calcium level were significantly associated with PSA flare (p = 0.001, p = 0.008 and p = 0.012, respectively). Multivariate logistic regression analysis showed that a change in the ALP level is an independent predictive factor for PSA flare (p = 0.017). CONCLUSIONS: ALP is a useful biomarker to differentiate PSA flare from early PSA progression during docetaxel chemotherapy in CRPC patients with bone metastasis.