Studies with C3(1)/SV40 Tag mice, which can spontaneously develop estrogen receptor (ER)-negative mammary and prostate tumors, have shown that DHEA at 4,000 mg/kg diet given between the 7 th and 19 th weeks of age, decreased the incidence of mammary tumors by 30% and tumor multiplicity by about 50% [9]. Here, ESR1 is linked to breast cancer.