This was a real world, observational study of adjuvant therapy with GnRHa for OFS in postoperative, premenopausal women with endocrine responsive breast cancer. This trial is designed to compare patients' QOL and treatment compliance measured by FACT-B and self-administered questionnaires during OFS treatment period. Total score of FACT-B and self-administered questionaries, and change from baseline will be calculated and summarized descriptively. Change from baseline will be compared between GnRHa 3-month and GnRHa 1-month using ANCOVA model with baseline value as a covariate.The number depends on the patients who received questionnaire during 18 months recruitment in planned 10 sites. This analytical plan assumes homogeneity across 10 sites so that strata is not considered.
