Counseling your patient about heritable breast cancer

The baseline frequency of breast cancer increases after age 30 from about 1% to about 10% by age 90. Breast cancer gene mutations cause much higher risks. Risks are nearly as high if two or more first-degree relatives (mother, sisters) had breast cancer when less than 50 years old. Risks are also elevated by occurrence of breast cancer at young ages in second-degree relatives (grandmothers, aunts). Certain rare syndromes are also associated with higher risks of breast cancer. Genetic testing for breast cancer gene mutations and for some of the syndromes is available but mutational heterogeneity limits its usefulness. Counseling about these aspects of breast cancer should be within the purview of any physician who manages patients who are at risk. The medical geneticist can assist in recognizing rare syndromes, identifying patients whose risks merit consideration of genetic testing or of prophylactic surgery, and in counseling in complex cases.