PGR and breast cancer: It is noteworthy that recent prospective human epidemiologic studies show compelling evidence for high total and saturated fat intake as a risk factor for ER + PR+ as well as HER2− breast cancer [44] and, strikingly, a strong association between the intake of red meat–derived animal fat and breast cancer risk in normal-weight, premenopausal women but not in overweight or obese women [5].