Genetic testing for breast and ovarian cancer is a simple and straightforward laboratory process for people who know the BRCA mutation that is running in their family.
Once the hard work of identifying the genetic component of a family's cancer has already been performed through DNA sequencing, other family members can use single site tests to look just for that DNA sequence.
The Single Site Test
Interpreting Your Results
The Single Site Test
Single-site analysis looks at one location on a person's BRCA1 or BRCA2 gene to see if they carry a specific mutation. This test can only be done for people who know the DNA sequence of the mutation that runs in their family, because the lab needs to know exactly where to look.
DNA sequencing is a complex process. This is because BRCA1 and BRCA2 genes are very large and hundreds of mutations known to be associated with breast and ovarian cancer have been found. Not surprisingly, single-site analysis is much cheaper and faster than DNA sequencing.
Interpreting Your Results
Because this test looks for a single, identified mutation in the BRCA1 or BRCA2 gene, the results are straightforward. You either have the mutation that runs in your family, or you don't. There is no chance of getting an ambiguous result.
- Positive Result. This means the test has detected the family mutation. The person tested has inherited her family's predisposition to breast and ovarian cancer. With this information, she (or he) can talk to a doctor about steps she can take to reduce her risk. These include: following more aggressive screening guidelines, making certain lifestyle changes, and considering the use of preventive medications and/or surgery.
- Negative Result. The test has not detected the family mutation. Since the person tested does not carry the family's genetic mutation, she (or he) is no longer considered at high risk for breast and ovarian cancer. She can follow screening guidelines for the average person.
It is very important to understand that a negative test result does not mean that a person is risk-free — no one is that lucky. It simply means that the person did not inherit her family risk, and so does not have an increased risk. She has the same risk for these diseases as the average person, and should follow regular screening guidelines for self exams and clinical check-ups.
Read more: One Family's Experience with Single Site Testing and DNA Analysis
References:
Arnold, N. et al. (1999). A highly sensitive, fast, and economical technique for mutation analysis in hereditary breast and ovarian cancers. Hum Mutat 14(4): 333-9.
Biesecker, B. B. and Brody, L.C. (1997). Genetic susceptibility testing for breast and ovarian cancer: a progress report. J Am Med Womens Assoc 52(1): 22-7.
Frank, T. S. and Braverman, A.M. (1999). The pros and cons of genetic testing for breast and ovarian cancer risk. Int J Fertil Womens Med 44(3): 139-45.
Mann, G. B. and Borgen, P.I. (1998). Breast cancer genes and the surgeon. J Surg Oncol 67(4): 267-74.
Neuhausen, S. L. and Ostrander, E.A. (1997). Mutation testing of early-onset breast cancer genes BRCA1 and BRCA2. Genet Test 1(2): 75-83.
Shattuck-Eidens, D., A. et al. (1997). BRCA1 sequence analysis in women at high risk for susceptibility mutations. Risk factor analysis and implications for genetic testing [see comments]. JAMA 278(15): 1242-50.
