MTT assay with reference to the clinical effect of chemotherapy.

Tumor cells from 40 patients were tested by MTT assay. Five thousand to sixteen thousand tumor cells were plated into 96-well microplates with various concentrations of anticancer agents. After incubation for 48 h, the absorbance of each well was detected with an EIA reader and the effects of the agents were evaluated as positive when the inhibition rate was equal to or more than 50%. Normal cells were also processed under the same conditions, and the absorbance for normal cells was lower than that of tumor cells with statistical significance (P less than 0.05). The efficacy rates of MMC, 5-FU, ADM, and CDDP were 16.7, 8.3, 13.9, and 5.6%, respectively. The overall accuracy of this assay for clinical effects was 83.3%, with one false-positive and five true-negative cases. This MTT assay was also assumed to be useful for in vitro chemosensitivity testing of fresh surgical specimens.