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

Abstract

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). 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(2)) or dose intensity (mg/m(2)/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. 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. 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.