Chemosensitivity testing of docetaxel and paclitaxel for gastric cancer using the Histoculture Drug Response Assay

4194 Background: In vitro chemosensitivity testing for individualized chemotherapy is known to improve the reponse rates although the impact on survival has not been adequately addressed. In vitro testing concentrations for new anticancer drugs such as the taxanes are unknown. Methods: Chemosensitivity tests for 30 gastric carcinoma tissues obtained at surgery were performed with Histoculture Drug Response Assay (HDRA) at 150μg/mL for 5FU and at three different concentrations for docetaxel (3, 30, 100 μg/mL) and paclitaxel (10, 60, 100 μg/mL). Inhibition rates (IR) were calculated using the formlula: (1-A/B) × 100% where A and B represent the mean absorbances of drug-treated and control wells, respectively. Results: For both drugs, the inhibition rates rose significantly as the testing concentration was elevated. Valid testing concentrations were determined as 10 μg/mL for paclitaxel and 30 μg/mL for docetaxel, based on the distribution of IRs between 0 and 100%. Five, 10 and 8 tumors were ranked as sensi...