RT Book, Section A1 Jameson, J. Larry A1 Fauci, Anthony S. A1 Kasper, Dennis L. A1 Hauser, Stephen L. A1 Longo, Dan L. A1 Loscalzo, Joseph SR Print(0) ID 1167064185 T1 Breast Cancer T2 Harrison's Manual of Medicine, 20e YR 2020 FD 2020 PB McGraw-Hill Education PP New York, NY SN 9781260455342 LK accessmedicine.mhmedical.com/content.aspx?aid=1167064185 RD 2024/04/25 AB The most common tumor in women; 266,120 women in the United States were diagnosed in 2019 and 40,920 died with breast cancer. Men also get breast cancer; F:M is 150:1. Breast cancer is hormone-dependent. Women with late menarche, early menopause, and first full-term pregnancy by age 18 years have a significantly reduced risk. The average American woman has about a one in nine lifetime risk of developing breast cancer. Dietary fat is a controversial risk factor. Oral contraceptives have little, if any, effect on risk and lower the risk of endometrial and ovarian cancer. Voluntary interruption of pregnancy does not increase risk. Estrogen replacement therapy may slightly increase the risk, but the beneficial effects of estrogen on quality of life, bone mineral density, and decreased risk of colorectal cancer appear to be somewhat outnumbered by increases in cardiovascular and thrombotic diseases. Women who received therapeutic radiation before age 30 years are at increased risk. Breast cancer risk is increased when a sister and mother also had the disease.