[Successful low-dose TS-1 administration in an elderly colon cancer patient with liver metastasis].

An 85-year-old man, who had undergone right hemicolectomy and partial hepatectomy for caecum cancer with liver metastasis, was diagnosed with recurrent multiple liver metastasis 10 months after surgery. TS-1 administration at a dose of 80 mg/day induced grade 3 anorexia, and after complete recovery from the adverse reaction, it was converted to a low-dose TS-1 administration at 40 mg/day. This treatment reduced the diameter of the liver metastasis and was continued for ten months without any adverse reaction. Pharmacokinetic analysis in this patient on low-dose TS-1 showed that Cmax and AUC of 5-chloro-2,4-dihydroxypyridine (CDHP) were equivalent to the values reported in cancer patients with normal renal function receiving standard-dose administration. TS-1 therapy may provide a safe and effective alternative to chemotherapy for elderly patients with advanced colorectal carcinoma. Pharmacokinetic analysis could be useful for determining the ideal dose of TS-1.