Preoperative enrollment
cancer, tumors, N0, breast cancer
METASTASIS, BREAST CANCER, CANCER, INVASIVE CANCER, SENTINEL LYMPH NODE, TUMORS, BILATERAL BREAST CANCER
Postmenopausal women aged < 76 years with histologically diagnosed primary invasive ER+/HER2−, T1c-T2, N0 and M0 breast cancer were enrolled. The definition of ER+was ≥ 10% of cells stained by immunohistochemical assay at each local site in a pretreatment needle biopsy specimen. Patients with proven metastasis to a sentinel lymph node, synchronous or asynchronous bilateral breast cancer, multiple tumors located in multiple breast segments, double primary invasive cancer untreated or diagnosed within 5 years after completing the treatment for the previous cancer, a history of breast cancer, or ongoing treatment with any continuous systemic corticosteroid, any estrogen-containing agent, or any selective ER modulator were ineligible.