Secondly, that chemotherapy should be considered or administered within 4 months of diagnosis for women under the age of 70 with AJCC T1c, Stage II, or Stage III hormone‐receptor‐negative breast cancer, and thirdly, that tamoxifen or a third‐generation aromatase inhibitor is considered or administered within 1 year of diagnosis for women with AJCC T1c, Stage II, or Stage III hormone receptor positive breast cancer. This evidence concerns the gene CYP19A1 and breast cancer.