BRCA1 / BRCA2 Test
Definition
BRCA is short for breast cancer gene. BRCA1 and BRCA2 are tumor suppressor genes; they prevent uncontrolled cell growth by repairing damaged DNA and keeping cells from dividing too quickly.
When a variant occurs, the gene or the protein it produces may not work well or may stop working altogether, which can lead to tumor development.
Who should be tested: Testing is not recommended for most people; harmful BRCA variants are found in only ~0.2% of the US population. It should be considered if the family history includes the following:
- Breast cancer before age 50
- Triple-negative breast cancer before age 60
- Breast cancer in a man
- Ovarian, fallopian tube or peritoneal cancer
- Metastatic prostate cancer
- Pancreatic cancer
People of Ashkenazi Jewish ancestry should also be evaluated, as BRCA variants are much more common in this community than in the general population.
Results
| Result | Meaning |
|---|---|
| Negative | No harmful change detected, but cancer risk depends on personal and family history |
| Uncertain (VUS) | A variant was found but it is not known whether it causes cancer |
| Positive | A harmful variant known to increase risk is present |
A positive result does not mean you will get cancer:
Not everyone with a harmful variant in BRCA1 or BRCA2 will develop cancer.
A positive result indicates increased risk; it cannot predict whether cancer will develop (see the Penetrance entry; BRCA is the classic example of reduced penetrance).
Risks and Limitations
At-home saliva tests look at only 3 common harmful variants. Because there are more than 1,000 known variants, home tests cannot rule out all harmful mutations; comprehensive laboratory testing is required.
Management options after a positive result:
- Intensified screening, earlier and more frequent check-ups
- Preventive medications, tamoxifen, raloxifene
- Surgical options, bilateral mastectomy, removal of the ovaries and fallopian tubes