Efficacy and safety of S-1 in patients with metastatic breast cancer: retrospective review in a single institution.

Background: It is extremely difficult to bring about a complete cure of metastatic breast cancer: the purpose of treatment is to prolong the patient's survival while maintaining their quality of life (QOL). The current retrospective study was conducted to find whether S-1, an orally administered 5-FU agent, can produce a therapeutic result in patients with recurrent metastatic breast cancer while maintaining their QOL.

Methods: Among the patients who were diagnosed at our institution to have recurrent metastatic breast cancer between November 2001 and December 2008, those who were treated with S-1 were selected and their records retrospectively reviewed.

Results: The analysis was conducted on 33 patients. The median number of regimens that these patients underwent was 2 (range 0-6). The overall response rate (ORR), clinical benefit rate (CBR), median time to treatment failure and overall survival were 30%, 42%, 152 days and 338 days, respectively. Among the 11 patients who were treated with S-1 in the first or the second line, ORR and CBR were 45.5 and 63.6%, respectively. Toxicity more than grade 3, leucopenia, neutropenia diarrhea, mucositis, and hand-foot syndrome were found in only 3%.

Conclusion: S-1 is well-tolerated by patients, promising a therapy while maintaining their QOL. When applied in the early stage of a disease in particular, the agent promises a very effective anti-tumor effect.