It has been suggested that loss of SULT1E1 expression in the transformation of normal breast tissue to breast cancer is an important factor in increasing the growth responsiveness of preneoplastic or tumor cells to estrogen stimulation [6], and that factors involved in the stimulation of the SULT1E1 could provide new possibilities for the treatment of patients with hormone-dependent breast and endometrial cancers. This evidence concerns the gene SULT1E1 and breast cancer.