Clinical outcomes by relative docetaxel dose and dose intensity as chemotherapy for Japanese patients with castration-resistant prostate cancer: a retrospective multi-institutional collaborative study.

Background: The aim of this study was to retrospectively investigate clinical outcomes by relative dose and dose intensity of docetaxel (DOC) as chemotherapy for Japanese patients with castration-resistant prostate cancer (CRPC). Methods: A total of 145 CRPC patients who received more than 4 courses of DOC chemotherapy at 14 hospitals between 2005 and 2011 were enrolled. Patients were divided into two groups-those receiving a higher or lower dose (mg/m) or dose intensity (mg/m/week). Differences between the groups regarding treatment outcomes and adverse events (AEs) were determined. Additionally, prognostic factors predictive of cancer-specific survival (CSS) in these patients were identified by both univariate and multivariate analysis. Results: The total patient group underwent a mean of 11.2 ± 7.4 DOC cycles, and the mean CSS after therapy was 15.6 ± 10.1 months. The higher-dose group had a better prostate-specific antigen (PSA) response than the lower-dose group. However, there was no significant difference between the groups in prognosis after DOC chemotherapy. Leukopenia and neutropenia were observed more frequently in the higher-dose group. Serum biomarkers (including PSA, lactate dehydrogenase and alkaline phosphatase), hemoglobin levels and presence of pain at initiation of chemotherapy, as well as the PSA nadir level on first-line hormone therapy, all were significant predictors of CSS. Conclusions: In the Japanese population, relatively low-dose DOC chemotherapy had no deleterious effect on the CSS of CRPC patients, and a lower incidence of AEs occurred, in spite of a diminished PSA response compared with those receiving a higher dose. [ABSTRACT FROM AUTHOR]