gynecology and obstetrics
Breast Cancer
Risk Factors for Breast Cancer
For women in the United States, cumulative lifetime risk of developing breast cancer is about 13% (1 in 8 [ Risk factor references ]). Much of the risk is incurred after age 60 (see table Factors that may affect breast cancer risk include the following: The incidence is highest among women ages 65 to 74 years. Median age at diagnosis is 63 years ( Risk factor references ). The median age at diagnosis is slightly younger for Black women (60 years old) compared to White women 63 years old) ( Risk factor references ). Black women have the highest death rate from breast cancer compared with other races or ethnicities; this may be in part because they have a higher rate of triple-negative breast cancer (negative for Having a 1st-degree relative (mother, sister, daughter) with breast cancer doubles risk of developing the cancer, but breast cancer in more distant relatives increases risk only slightly ( Risk factor references ). When mutations is about 17% ( Risk factor references , Having had in situ or invasive breast cancer increases risk. Risk of developing cancer in the contralateral breast after mastectomy is about 0.4%/year of follow-up ( Risk factor references ). Having LCIS increases the risk of developing invasive carcinoma in either breast by about 7 to 12 times ( Risk factor references ); invasive carcinoma develops in about 1 to 2% of patients with LCIS annually. Early menarche or late menopause increases risk. Risk increases with increasing age at first pregnancy ( Risk factor references ). History of a lesion that required a biopsy is associated with a slightly increased risk. Women with multiple breast masses but no histologic confirmation of a high-risk histology should not be considered at high risk. Benign lesions associated with a slightly increased risk of developing invasive breast cancer include complex fibroadenoma, moderate or florid hyperplasia (without atypia), sclerosing adenosis, and papilloma. Risk is about 3 to 5 times higher than average in patients with atypical ductal or lobular hyperplasia ( Risk factor references ). Dense breast tissue seen on screening mammography is associated with a 1.2- to 2.1-fold increased risk of breast cancer ( Risk factor references ). Study results vary regarding the use of oral contraceptives and risk of breast cancer. Some studies have found a small increased risk in current or recent users ( Risk factor references ). Menopausal Hormone Therapy : Exposure to radiation therapy of the chest up through 45 years old increases risk, with the highest increase for those exposed between ages 10 to 14 years ( Risk factor references ). Mantle-field radiation therapy for Hodgkin lymphoma about quadruples risk of breast cancer over the next 20 to 30 years. Diet:Diet may contribute to development, growth, or prognosis of breast cancers, but conclusive evidence about the effect of a particular diet (eg, one high in fats) is lacking. Postmenopausal women with obesity are at increased risk of breast cancer; studies show a 10% increase in risk for each additional 5 body mass index (BMI) units above normal BMI ( Risk factor references ). Smoking and alcohol use appear to be associated with an increase in breast cancer risk; the increase with alcohol intake is dose-dependent ( Risk factor references , TheBreast Cancer Risk Assessment Tool(BCRAT), or Gail model, can be used to calculate a women's 5-year and lifetime risk of developing breast cancer. 1.American Cancer Society: Key Statistics for Breast Cancer. Accessed May 4, 2023. 2.American Cancer Society: Survival Rates for Breast Cancer. Accessed March 29, 2023. 3.Collaborative Group on Hormonal Factors in Breast Cancer: Familial breast cancer: collaborative reanalysis of individual data from 52 epidemiological studies including 58,209 women with breast cancer and 101,986 women without the disease.Lancet358(9291):1389-1399, 2001. doi:10.1016/S0140-6736(01)06524-2 4.Kuchenbaecker KB, Hopper JL, Barnes DR, et al: Risks of breast, ovarian, and contralateral breast cancer for BRCA1 and BRCA2 mutation carriers.JAMA317 (23):2402–2416, 2017. doi: 10.1001/jama.2017.7112 5.Breast Cancer Association Consortium; Dorling L, Carvalho S, Allen J, et al: Breast cancer risk genes — Association analysis in more than 113,000 women.N Engl J Med4;384 (5):428–439, 2021. doi: 10.1056/NEJMoa1913948 6.Giannakeas V, Lim DW, Narod SA: The risk of contralateral breast cancer: a SEER-based analysis.Br J Cancer125(4):601-610, 2021. doi:10.1038/s41416-021-01417-7 7.American Cancer Society (ACOG): Lobular Carcinoma in Situ (LCIS). Accessed May 4, 2023. 8.Collins LC, Baer HJ, Tamimi RM, et al: Magnitude and laterality of breast cancer risk according to histologic type of atypical hyperplasia: results from the Nurses' Health Study.Cancer109(2):180-187, 2007. doi:10.1002/cncr.22408 9.American College of Obstetricians and Gynecologists (ACOG): Committee opinion no. 625: Management of women with dense breasts diagnosed by mammography.Obstet Gynecol125 (3):750–751, 2015. Reaffirmed 2020. doi: 10.1097/01.AOG.0000461763.77781.79 Accessed May 4, 2023. 10.American College of Obstetricians and Gynecologists (ACOG): Hormonal contraception and risk of breast cancer: Practice advisory. Published 2018, reaffirmed 2022. 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