ESR1 and breast cancer: Among 561 BC cases with available ER, PR, Ki-67, tumor size, tumor location, lymph nodes metastasis, distance metastasis, TNM stage, and primary or recurrent information, 380 (67.7%) cases were ER positive, 328 (58.5%) cases were PR positive, 371 (66.1%) cases had high Ki-67, 238 (42.4%) cases had tumor size > 2 cm, 267 (47.6%) cases were lymph nodes metastasis positive, 517 (92.2%) cases had distance metastasis of M0, 366 (65.2%) cases were at I-II TNM stage, and 424 (75.6%) cases were primary.