Living with cancer blog
Testing for BRCA1 and BRCA2 genes can identify people who have a higher risk of developing breast and ovarian cancer. If a positive DNA mutation is discovered in one person, other family members can be tested to determine if they also carry a BRCA mutation.
Once you learn if you carry an inherited BRCA gene mutation, you can understand better your personal risk of developing breast or ovarian cancer. You can talk with a genetic counselor and your health care provider about measures you can take to reduce your cancer risk.
To reduce your cancer risk, you may choose to:
- Increase the frequency of screening tests to detect early cancer
- Take preventive medications that have been proven effective in lowering breast cancer risks (chemoprevention)
- Undergo preventive surgery (removal of breast tissue, ovarian and fallopian tubes)
However, not everyone who has their DNA tested for BRCA mutations gets clear results. There are times when the genetic tests show variants of uncertain significance (VUS) that have undefined risks of cancer. Individuals found to have these VUS cannot benefit from individualized cancer risk assessment that comes from a positive test result. In addition, a VUS cannot be used to determine risks of cancer among relatives of the tested individual.
Recently, scientists from around the world collaborated on developing a new model to help understand the clinical meaning of some of the known VUS in the BRCA genes. The model mathematically combines multiple lines of evidence to produce a number (or score), called the posterior probability. This probability score reflects the result from calculations that measure the chance that a VUS is or is not likely to be a real BRCA mutation or a harmless difference.
This new model is helping people who have VUS better understand their personal risk. However, more research is needed to understand all the variants as they are discovered. The field of genetics is evolving every day, so look for updates to this from Mayo Clinic.
For more on VUS and probability scores, check out mayoresearch.mayo.edu/mayo/research/womens_cancer/projects.cfm.
I'd love to hear from those of you who have experienced BRCA testing. Share your thoughts with others through the blog.
Aug. 10, 2012
Sheryl M. Ness, R.N.