CYP19 Genetic Polymorphism & Aromatase Inhibitor(AI)

Inclusion Criteria: 1. The patient must sign the informed consent. 2. The patient must sign the informed consent of genetic screening test. 3. The patient must be between 18 years old and 80 years old who can make a decision independently. 4. The patient must be post-menopause status. 5. The patient should be the stage 1,2 or 3 of the breast cancer. 6. The test result of the estrogen receptor or progesterone receptor is positive, so the patient should be taking the medication of AI (Aromatase Inhibitor). Exclusion Criteria: 1. The patient is pre-menopause status. 2. The test result of serum FSH level is below 30mU/ml. 3. The test result of the hormone receptor(ER \& PR) is negative or unknown. 4. Patient's breast cancer stage is 4 which has systemic metastatics.