Feasibility study of TS-1 additional therapy for the triple-negative breast cancer received neoadjuvant or adjuvant chemotherapy (SBCCSG14).
162 Background: Prospective randomized clinical trials have demonstrated a significant advantage from postoperative adjuvant chemotherapy for patients with breast cancer. However, triple-negative breast cancer is high rate of early recurrence. Therefore, patients who do not achieve pathological complete response (pCR) for neoadjuvant chemotherapy have worse long-term survival than patients who achieve pCR. Treatment after adjuvant chemotherapy and neoadjuvant chemotherapy is not established yet. We notice that TS-1 improve early recurrent rate of breast cancer. TS-1 proved good response for advanced breast cancer and long-term therapy is possible. We planned the study for the purpose of inspecting it about the safety, completion and efficacy of giving TS-1 after standard therapy of triple negative breast cancer for one year. Methods: The patients with stage ±/II/ III triple negative breast cancer received neoadjuvant or adjuvant chemotherapy and surgery and/or radiotherapy. Furthermore, the cases of neoadjuvant chemotherapy did not achieved pCR. After that, dose of TS-1 is 80mg/m² administered orally daily for 2 weeks followed by a 1-week rest period given as 3-week cycles. Results: 63 patients were enrolled, including 44 patients received neoadjuvant chemotherapy and 19 patients received adjuvant chemotherapy. The average age is 50 years (28-68 years). 38 cases (60.3%) brought oral administration for one year to completion. The reasons of discontinuance were 15 cases of toxicity and 10 cases of recurrence. Average relative dose intensity was 80%. The compliance of TS-1 was 70.1% (222.4 days). Overall survival of 3 years was 86.47%, progression-free survival 50.8%. The overall incidence of toxicity was 54 cases (85.7%), and grade 3 toxicity occurred in 21 cases (33.3%). Conclusions: The compliance of TS-1 was approximately equal to the compliance for gastric cancer in spite of receiving treatments of anthracycline and/or taxane. The toxicity was approximately equal to the results for metastatic breast cancer. TS-1 administered orally for one year was feasible for triple negative breast cancer received standard therapy. Clinical trial information: UMIN000001414.