Predictive chemotherapy of advanced breast cancer directed by MTT assay in vitro

In order to investigate the predictive value of in vitro MTT assay for directing chemotherapy of breast cancer patients, from 1992 to 1995, 156 advanced breast cancer patients who had evaluable lesions were recruited for a prospective study. Of them 83 had MTT assay before chemotherapy; the 73 patients in the MTT sensitive group received chemotherapy according to the result of the MTT assay. The other 10 patients in the MTT resistant group and 73 patients in the control group were given chemotherapy according to clinicians' discretion. The response rate in the MTT sensitive group was 76.7% (56/73). There was statistically significant difference as compared with 0 (0/10) in the MTT resistant group and 43.8% (32/73) in the control group. Between in vitro and in vivo, the overall coincident rate was 79.5% [(56 + 10)/83]. In the MTT sensitive group, the response rate of the subgroups of lesions and the chemotherapy regiments tended to be higher than that in the control group. Patients in the MTT sensitive group had longer response and survival than those in the control group. However, there was no statistical difference in the median response duration and the median survival between the two groups. Further exploration of in vitro chemosensitivity testing by MTT assay for patients with advanced breast cancer is warranted.