Gallen International Conference 2013, the definition of luminal A breast cancer was proposed as ER and PgR positive, HER2 negative and Ki-67 “low.” No absolute values of a cut-off between “high” and “low” were suggested during this conference; locally useful cut-off points are adopted in daily practice to distinguish between luminal A and B [20]. Here, ESR1 is linked to breast carcinoma.