Changes in fPSA level could discriminate tPSA flare-up from tPSA progression in patients with castration-refractory prostate cancer during the initial phase of docetaxel-based chemotherapy

Abstract

To evaluate whether changes in fPSA level could predict tPSA flare-up in patients with castration-refractory prostate cancer during the initial phase of docetaxel-based chemotherapy. We retrospectively identified 79 consecutive patients who received docetaxel-based chemotherapy at our institution. The treatment protocols included docetaxel 75 mg/m² every 21 days, with either prednisone 5 mg twice daily or estramustine 280 mg three times daily on days 1-5; treatment with dexamethasone preceded docetaxel therapy. All PSA values were determined before every cycle of docetaxel-based treatment. According to changes in tPSA level, 79 patients were divided into 3 groups: response (group 1), progression (group 2) and flare-up (group 3). fPSA and tPSA levels showed different patterns in groups 1, 2 and 3. Changes in fPSA level were independent of the changes in tPSA level in group 3, which decreased during chemotherapy. However, comparing with fPSA changes in group 3, changes in fPSA level were in accordance with tPSA changes in groups 1 and 2. Estimated median survival in groups 1, 2 and 3 was 23, 13 and 21 months, respectively. Median survival for patients in groups 1 (P = 0.008 vs group 2) and 3 (P = 0.029 vs group 2) is significantly longer than for patients who experienced progressive disease under therapy. However, there was no statistically significant difference in survival between groups 1 and 3. In the present study, we observed that changes in fPSA level could possibly discriminate tPSA flare-up from tPSA progression in patients with castration-refractory prostate cancer during the initial phase of docetaxel-based chemotherapy.