To evaluate the economic impact of regimens including the oral anticancer drug S-1 (a combination of tegafur, gimeracil, and oteracil), we performed cost-minimization analysis to compare the medical costs of S-1 plus irinotecan (IRIS) with those of conventional intravenous treatment with oxaliplatin or irinotecan plus fluorouracil and folinic acid (mFOLFOX6/FOLFIRI) in patients with advanced colorectal cancer. Patients with advanced colorectal cancer were extracted from the ordering system database for outpatients in Showa University Hospital. Direct medical costs and patients' time-related costs were calculated from the hospital billing data and the average Japanese labor wage, respectively. The results were analyzed from a limited societal perspective. Twenty-nine patients with advanced colorectal cancer were identified, and 25 IRIS regimens, 11 mFOLFOX6 regimens, and 5 FOLFIRI regimens were registered. Mean (± SE) monthly costs of treatment were 183,682 (± 4,767) yen for IRIS regimens and 279,077(± 13,345) yen for mFOLFOX6/FOLFIRI regimens. The monthly cost of IRIS regimens was significantly lower than that of mFOLFOX6/FOLFIRI regimens (P < 0.0001). IRIS regimens are cost-saving compared to mFOLFOX6 or FOLFIRI regimens for the management of advanced colorectal cancer.
