CANCER PREVENTION IN HIGH-RISK GROUPS
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Risk factors include age, early menarche, nulliparity or late first pregnancy, high body-mass index, radiation exposure before age 30 years, hormone-replacement therapy (HRT), alcohol consumption, family history, presence of mutations in BRCA1 or BRCA2, and prior history of breast neoplasia. Models are able to predict a woman’s risk level (see www.cancer.gov/cancertopics/pdq/treatment/breast/healthprofessional#Section_627).
MRI scanning is a more effective screening tool than mammography in women with a familial breast cancer risk.
Women whose risk exceeds 1.66% in the next 5 years have been shown to have a 50% reduction in breast cancer from taking tamoxifen or raloxifene. Aromatase inhibitors have generally been superior to tamoxifen in the adjuvant treatment of hormone-sensitive breast cancer, and one of them (exemestane) reduces the risk of breast cancer by 65% in postmenopausal women at increased risk. Women with strong family histories should undergo testing for mutations in BRCA1 and BRCA2. Mutations in these genes carry a lifetime probability of >80% for developing breast cancer. Bilateral prophylactic mastectomy prevents at least 90% of these cancers but is a more radical prevention than the usual treatment for the disease. In addition, bilateral salpingo-oophorectomy reduces ovarian and fallopian tube cancer risk by about 96% in women with BRCA1 or BRCA2 mutations.