Freneaux et al. demonstrated that a higher histological grade, a higher mitotic index, a higher apoptotic index, and a lower rate of ER positivity were found in Brca1-associated breast cancers and that the rate of Bcl-2-positive tumors was lower in Brca1-associated cancers than in cancers without Brca1 mutation, thus suggesting that the decrease in Bcl-2 expression might account for the high apoptotic and proliferative rates observed in Brca1-associated breast cancers [27]. This evidence concerns the gene ESR1 and cancer.