Clinical usefulness of chemosensitivity test for advanced colorectal cancer

We assessed the usefulness of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay in the evaluation of appropriate adjuvant cancer chemotherapy for patients with advanced colorectal cancer. We analyzed 405 cases of colorectal cancer treated between January 1990 and August 1999 in terms of the MTT assay and survival outcome. Patients with Dukes' C and D were classified into a "surgery alone" group (n = 53), a "sensitive" group who received drugs that had a greater than 50% inhibition rate by MTT assay (n = 23), or "resistant"" group who were insensitive to the chemotherapy drugs (n = 124). Statistically significant differences in survival outcome were observed between the groups, with the sensitive group showing significantly better survival compared with the resistant group (p = 0.0158) and the surgery-alone group (p = 0.0004). Our results suggest that the MTT assay may be useful in evaluating the optimum adjuvant chemotherapy for patients with advanced colorectal cancer.