The new primary chemotherapy with S-1 and docetaxel for advanced breast cancer: A first report of N-1 trial.
e11560 Background: We reported the result of the efficacy and toxicity of S-1 combined with docetaxel (S-1+DOC) in ASCO 2011 (abstract No.1075). It showed good objective response rate (ORR) and some cases showed of complete response (CR) before middle of 8 cycles regimen. But this regimen was difficult to keep compliance of per oral S-1 intake. To improve pathological CR (pCR) rate, we planned a new protocol of primary chemotherapy with S-1+DOC (N-1 trial). Methods: Patients with advanced breast cancer (stage II-IV) were treated with i.v. docetaxel (40mg/m2) on day1 and oral S-1 (80mg as FT/m2/day) on day1 to 14 every 3 weeks for 4 cycles. According to the RECIST criteria, patients with CR were underwent operation, partial response were continued more 4cycles of S-1+DOC. Stable disease or progressive disease cases were changed regimen for EC or Trastuzumab and Paclitaxel (HT) according to their HER2 status. Adequate supportive therapy was provided for typical adverse events. Primary endpoint is a pCR rate. Secondary endpoints are ORR, breast conservation rate and safety. Results: Between 2009 and 2011, Forty-two patients were originally entered. After 4 cycles of S-1+DOC, CR was noted in 6 cases, and PR in 20 cases. 8 cases of SD and 1 case of PD were underwent EC, 4 cases of SD were underwent HT. Among 36 patients who had completed the whole regimen, 30.7% achieved pCR. ORR was 79.4% and breast conservation rate was 97.4%. Patients could keep an intake more than 80% dose of S-1 was 87%. Adverse events over grade3 were peripheral sensory neuropathy, nausea, nail change and neutropenia. Grade 3, 4 of neutropenia was noted in 62%. Conclusions: The new primary chemotherapy with S-1 and Docetaxel is expected to exhibit satisfactory efficacy and showed the possibility of shortened the term of primary chemotherapy. In order to establish this treatment, it is important to proper response assessment.