[The platelet-sparing effect of carboplatin and docetaxel combination chemotherapy for lung cancer]

Paclitaxel and carboplatin chemotherapy is reported to be a platelet-sparing drug combination. The objective of this study was to elucidate whether docetaxel with carboplatin has a similar platelet-sparing effect. This study investigated the time-course of the changes in the platelet count and the circulating concentration of thrombopoietin (TPO), a platelet growth factor, during combination chemotherapy consisting of carboplatin and docetaxel. Eleven patients with advanced lung cancer were enrolled; 8 receiving carboplatin and docetaxel (docetaxel group), and 3 receiving carboplatin and irinotecan (irinotecan group). The time-course profiles of the platelet count and the circulating TPO concentration were determined and compared between the two groups. The platelet count decreased significantly only in the irinotecan group, and on day 15 after therapy the thrombocytopenia was pronounced in comparison with that in the docetaxel group. The circulating TPO concentration remained almost constant in the irinotecan group, with no significant increases, while that in the docetaxel group was increased significantly on day 4 (p < 0.05), day 8 (p < 0.05), and day 15 (p < 0.01) after therapy. There was also a significant difference between the docetaxel group and irinotecan group with respect to circulating TPO concentration (p < 0.05). These results suggest that docetaxel might also have a platelet-sparing effect on the anti-platelet activity of carboplatin, mediated by levels of circulating TPO concentration.