Pilot Study of Irinotecan and S-1 (IRIS) for Advanced and Metastatic Breast Cancer

Background/aim Irinotecan is rarely used on the metastatic breast cancer (MBC) setting. S-1 is an oral mixture of tegafur, gimeracil and oteracil. We conducted this pilot study to assess efficacy and safty of chemotherapy with combined irinotecan and S-1 (IRIS). Patients and methods Irinotecan was given intravenously at 80 mg/m2 on days 1 and 8 and S-1 was given orally at 80-120 mg/day depending on body surface area for 2 weeks, repeating the cycle every 3 weeks. Results Twenty-two patients were enrolled in the study. Median age was 50.5 years (range=26-72). Nineteen patients were evaluable for response. Median overall survival and progression-free survival were 672 days (95% CI=420-967) and 166 days (95% CI=76-814), respectively. Conclusion The IRIS regimen has an acceptable safety profile and modest efficacy against MBC in patients previously heavily treated with chemotherapy. This regimen has potential to treat MBC.