A case of bone metastasis of colon cancer that markedly responded to S-1/CPT-11 combination chemotherapy and became curable by resection

BACKGROUND An oral combined fluoropyrimidine anticancer drug, tegafur/gimeracil/oteracil potassium (S-1), has recently been used alone or in combination for colon cancer. CASE PRESENTATION The patient was a 42-year-old man with sigmoid colon cancer with direct invasion of the urinary bladder and multiple costal metastases. A diagnosis of T4, M1, stage IV sigmoid colon cancer was made, and curative resection was considered impossible. S-1 at 50 mg/m2 was administered by oral route from day 1 to day 14. Irinotecan (CPT-11) at 40 mg/m2 was administered by intravenous day 1 and 15. This treatment was followed by 2 weeks absent period, and repeated every 4 weeks. Six cycles of administration were performed in total. Following this treatment, the multiple costal metastases resolved. Down-staging to T3, M0, stage IIA was achieved, and curative resection was judged to be possible. CONCLUSION Occasional cases in which S-1/CPT-11 therapy was effective have been recently reported. The patient's tumor became resectable despite the discovery of colon cancer associated with bone metastasis at the initial examination, offering hope for cancer patients.