PSA flare-up in patients with hormone-refractory prostate cancer (HRPCA) receiving docetaxel-based chemotherapy: Incidence and differentiation from progressive disease

Abstract

14523 Background: Docetaxel-based chemotherapy displays the standard therapy for patients with hormone-refractory prostate cancer. A subset of patients will experience an initial PSA increase after initiation of therapy followed by a subsequent PSA decrease. The aim of our study was to investigate the incidence of this phenomenon and to identify factors that differentiate the flare-up from progressive disease. Methods: We retrospectively analyzed the patient records of 46 patients who received docetaxel as monotherapy or in combination with either mitoxantron or estramustine for hormone-refractory prostate cancer. PSA flare-up was defined as an initial PSA increase of more than 25% after initiation of therapy over baseline followed by a PSA decrease of at least 75% compared to the maximum increase over baseline. Progressive disease was defined as a PSA increase of at least 25% over baseline in patients with no PSA response which had to be confirmed four weeks later. Results: Of 46 patients who received docetaxel-based chemotherapy 16 (34.8%) showed a PSA decrease of at least 50%, 6 (13.0%) between 30–50%, 17 (37.0%) had stable disease and 7 (15.2%) patients experienced progressive disease. An initial PSA increase followed by a subsequent PSA decrease was seen in 6 (13.0%) of the patients. Median PSA increase compared to baseline was 81.0% (25–239). The median following PSA decrease was 110.5% (77–160) compared to the initial increase. Median PSA doubling times of patients with PSA flare up or progressive disease were 113.3 and 100.7 days (p = 0.7941), respectively. Conclusions: PSA flare-up seems to be a common phenomenon in patients being treated with docetaxel-based chemotherapy for hormone-refractory prostate cancer. In order not to prevent those patients from a subsequent PSA decrease by early cessation of therapy it would be useful to discriminate them from patients with progressive disease. According to the results of our study PSADT does not differ between patients with flare-up or progressive disease and can therefore not be used to distinguish between the two. No significant financial relationships to disclose.