It’s important to understand that only five to 10 percent of all breast cancer cases are hereditary. A common cause (85 percent) of those few hereditary cases is a mutation in one of the BRCA genes. If your mother had breast cancer, you may be a candidate for genetic testing – or your mother may be a better candidate. If a patient is diagnosed as having a positive BRCA test, that means we have identified a place on that gene where the mutation is located. Other family members can be tested at that specific location. Their testing is then very specific and much less expensive.
BRCA1 and BRCA2 are genes (we all have BRCA genes) that produce tumor suppressor proteins. These proteins help repair damaged DNA and, therefore, play a role in ensuring the stability of the cell’s genetic material. When either of these genes is mutated, or altered, DNA damage may not be repaired properly. As a result, cells are more likely to develop additional genetic alterations that can lead to cancer.
A mutation of BRCA1 or BRCA2 might be one piece of the puzzle. The mere presence of a gene mutation does not mean a woman will develop cancer; it means the woman’s risk is elevated.
Who is eligible for testing?
According to guidelines from the National Comprehensive Cancer Network (NCCN), testing is recommended when a patient is diagnosed with early-onset breast cancer, has triple-negative breast cancer or has two separate breast cancers. Family history also plays an important role and having a diagnosis of breast cancer and close relatives with breast or ovarian cancer are part of the criteria. Male breast cancer is extremely rare and is considered a red flag for a hereditary syndrome. There are additional criteria for unaffected individuals when it is not possible to test someone in the family with breast or ovarian cancer. Family history again is considered a major factor in determining eligibility for testing.
Unfortunately, in many cases a close relative with breast cancer and/or ovarian cancer might be unavailable for testing. So, we’re left with many questions: Did the mother actually have a BRCA mutation? If so, her daughter would have a 50/50 chance of having inherited the same mutation.
Find a genetic counselor.
If you’re considering testing, it’s important for you to find a genetic counselor or other health care professional prior to doing any testing. The first phase will include a family history going back three generations. You will have an appointment where genetic principles and risk-reducing options will be discussed, and only then will a blood or saliva sample be taken and sent to a lab. The results could be back in seven to 10 days, and the genetics professional will go over the results with you.
If a BRCA test comes back positive for a harmful mutation, that person is then diagnosed with hereditary breast and ovarian cancer syndrome. Prevention strategies to reduce risk would include additional breast and ovarian screening, and perhaps chemoprevention or preventive surgery.
A negative result when a known mutation is present in the family would mean that the person tested did not inherit a mutation. This is a true negative because even if a mother had the BRCA gene mutation, her daughter did not inherit the mutation. This lowers the daughter’s breast cancer risk to the same level as the general public.
If a patient tests negative but we do not know the genetic status of family members diagnosed with cancer, we would keep that patient in an increased risk group because of her family history. Keep in mind that while BRCA1 and BRCA2 are the biggest players in hereditary cancers, there are rarer genetic syndromes that can also increase risk.
The trend in genetics is to look at large groups of genes instead of one or two. This is called panel testing and is becoming more common. Current genetic testing criteria are pretty specific and relate to a patient’s personal and family history of cancer.