We divided our cohort of 168 patients into the molecular subtypes of breast cancer: 60 luminal A (ER+ and/or PR+, HER2−, Ki-67 low), 59 luminal B (ER+ and/or PR+, HER2− and Ki-67 high or HER2+ and Ki-67 low/high), 33 triple negative (ER−, PR−, HER2−) and 5 HER2+ (ER−, PR−, HER2+) patients. This evidence concerns the gene ESR1 and breast cancer.