The Test Sample
What is being tested?
BRCA1 and BRCA2 are two tumor suppressor genes. Normally, these genes help prevent cancer by producing proteins that suppress abnormal cell growth. Certain changes (mutations) in these genes affect their normal function, thereby potentially allowing cell growth to occur uncontrolled. This test detects mutations in these genes that are linked mainly with hereditary breast and ovarian cancers.
According to the American Cancer Society (ACS), about 225,000 women are diagnosed with invasive breast cancer each year and about 22,000 with ovarian cancer. Of these cancers, about 5-10% will be due to a harmful mutation in BRCA1 or BRCA2 genes. Men can also inherit an increased risk of developing breast cancer, occasionally from mutations in BRCA1, but primarily from mutations in the BRCA2 gene.
Women with inherited mutations in BRCA1 or BRCA2 have up to an 85% lifetime risk of developing breast cancer and a 30-50% lifetime risk of developing ovarian cancer. Men and women may be at slightly increased risk for other cancers as well. Breast cancer in women with inherited mutations is likely to develop at an earlier age, before menopause.
BRCA mutations are inherited and passed from generation to generation. Each person will have two copies of BRCA1 and BRCA2, one copy from each parent. Mutations may be present in either copy of the gene. The DNA in cells is used to detect mutations in the BRCA genes. Cells from the blood or cells from the mouth are the most easily accessible sources of that DNA.
How is the sample collected for testing?
The test for BRCA mutations is done on a blood sample collected by needle from a vein in the arm or from a special oral rinse that collects cells from the mouth. The test does not require surgical biopsy of breast or ovarian tissue.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed, but genetic counseling is strongly recommended.