A randomized controlled study comparing Anastrozole+TS-1 as postoperative chemotherapy in ER positive metastatic breast cancer

INTERVENTION: Group A: Anastrozole (1mg/day) is administratedd orally on days 1‐21 until progression or discontimuation of drug (ex. Adverse event et al.)for PgR(+) Breast cancer Group B: Anastrozole (1mg/day) is administratedd orally on days 1‐21 and S‐1 (80mg/m2/day) is administrated orally on days 1‐21 every 28 days until progression or discontimuation of drug (ex. Adverse event et al.)for PgR(+) Breast cancer Group C: Anastrozole (1mg/day) is administratedd orally on days 1‐21 until progression or discontimuation of drug (ex. Adverse event et al.)for PgR(‐) Breast cancer Group D: Anastrozole (1mg/day) is administratedd orally on days 1‐21 and S‐1 (80mg/m2/day) is administrated orally on days 1‐21 every 28 days until progression or discontimuation of drug (ex. Adverse event et al.)for PgR(‐) Breast cancer CONDITION: Breast Cancer PRIMARY OUTCOME: Response rate SECONDARY OUTCOME: Overall survival (OS), Disease free survival (DFS), Adverse events, Examination of the relevance of 5‐FU relative factors (thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), orotate phosphoribosyl transferase (OPRT) mRNA) and HER2 profile with efficacy, Clinical benefit INCLUSION CRITERIA: 1) Histologically confirmed Breast Cancer 2) Estrogen Respecter positive (10% cut off) 3) Performance Status (ECOG) 0‐2 4) Measurable disease 5) Without prior chemotherapy nor use of Anastrozole 6) Adequate organ functions 7) Estimated life expectancy of at least 3 months 8) Postmenopausal 9) Oral intake is possible 10) Written informed consent