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About 5-10% of breast cancer cases are believed to be due to genetic mutations, specifically at genes BRCA1 and BRCA2. Estimates of the risk of breast cancer in women with such mutations suggest that by age 30, the cumulative risk is 3.2%, 19.1% by age 40, 50.8% by age 50, and 85% by age 70. These estimates must be viewed with caution, since data are derived from families with clinically evident clusters of cancer, early or multiple cancer, or other variables of lesser concordance with the general population.
Of women who have had breast cancer, the estimated risk of having a contralateral cancer by age 70 is 64%. Additionally, ovarian cancer risk is elevated in one subgroup of BRCA1 patients. For women, BRCA1 and BRCA2 carry similar risks; for men, BRCA2 has been associated with male breast cancer in some families with no manifestation of female breast cancer.
Some of the Task Force recommendations pertaining to women, or their family members, known to carry these mutations, include:
1. Breast self-examination monthly beginning at age 18-21.
2. Annual or semiannual clinical breast examination beginning at age 25-35.
3. Annual mammography beginning at age 25-35.
4. Annual or semiannual transvaginal ultrasound and serum CA-125, beginning at age 25-35.
5. Be aware of increased risk of colorectal CA, and follow standard screening.
6. Prophylactic mastectomy and oophorectomy, though not proven to reduce cancer risk, are options.
Detailed provisions for hormone replacement therapy, chemoprevention, and lifestyle modification are contained in the recommendations. Parallel recommendations for men (e.g., for prostate disease) are also included.
Burke W, et al. JAMA 1997;277: 997-1003.