BRCA-1 and BRCA-2 (breast cancer)
BREAST CANCER GENE 1 and breast cancer gene 2, the first genes in which researchers identified mutations that correlate to increased susceptibility to BREAST cancer and OVARIAN CANCER. About one in six women who have either of these cancers have mutations in either or both of the genes. Many are women who have a known family history of breast cancer or ovarian cancer. The presence of mutations in either of these genes means a woman has an increased risk for developing breast or ovarian cancer but it does not mean cancer is inevitable. Researchers do not yet know the extent to which BRCA-1/BRCA-2 gene mutations affect a woman’s risk for cancer, though believe they are responsible for about 5 percent of breast and ovarian cancers. Many factors influence the development of cancer; genetics remains only one among them.
Testing for BRCA-1/BRCA-2 is controversial because there are few preventive or therapeutic actions women or doctors can take as a result of knowing a positive result. Under current practice guidelines, doctors may choose to offer such testing to women who have first-degree relatives (mother, daughter, sister, grandmother) who have breast cancer or ovarian cancer or who are themselves under age 50 at the time of being diagnosed with either type of cancer. A positive result (mutations are present) may be a factor in prophylaxis or treatment decisions, though is by itself not a strong enough indicator to be the basis for such decisions. Nor is a negative result any indication that a woman will not develop breast or ovarian cancer. Because doctors can detect breast and ovarian cancers early through regular examinations, most health experts believe such examinations remain the most effective means for early diagnosis and treatment regardless of genetic influences.