Clinical predictive value of in vitro anticancer drug sensitivity test for the therapeutic effect of adjuvant chemotherapy in patients with stage II–III colorectal cancer

Clinically useful predictors of the efficacy of adjuvant chemotherapy following curative colorectal surgery remain to be determined. In the present study, we investigated the clinical utility of the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) as a predictor of the therapeutic response to 5-fluorouracil (5-FU)-based adjuvant chemo-therapy in patients with stage II–III colorectal cancer. CD-DST was conducted using tumor samples surgically obtained from 189 patients. The therapeutic effect of 5-FU-based regimens between high (high-group) and low (low-group) sensitivity groups and a group that did not receive chemotherapy [CTx(-) group] was compared. CD-DST was successfully performed in 151 out of the 189 patients (79.9%), 87 of whom received 5-FU-based adjuvant chemotherapy after surgery. Twenty-seven of these 87 patients (31.0%) were classified as the high-group and the remaining 60 (69.0%) as the low-group. The 5-year recurrence-free survival (RFS) in the high-group was significantly higher compared to that in the low- and the CTx(-) groups. No differences in the 5-year RFS were observed between the low- and CTx(-) groups. In conclusion, CD-DST appears to be useful for predicting the therapeutic response to 5-FU-based adjuvant chemotherapy in patients with stage II-III colorectal cancer.