About 5 to 10% of breast cancer cases are linked to inherited genetic mutations. That’s why doctors recommend that all women complete a risk assessment before age 25 to determine whether they need additional genetic testing to detect cancer-related BRCA mutations.
But women who got their genetic test results back some time ago – before 2013 – might find that they missed mutations that we can easily test for at the moment.
In fact, a recent study found that one in six women (17.3%) who tested negative for dangerous mutations at the start of the test actually did have a dangerous variant when they retested on average five years later.
“There are probably thousands of people who need to be retested,” breast cancer researcher Dr. Sofia Merajver told the Washington Post.
Why were tests less accurate before?
You’ve probably heard of BRCA1 and BRCA2: when these genes mutate, they pose the highest risk of breast cancer. When cancer develops in people with mutations in these genes, it is often more aggressive.
These genes were identified in the 1990s by Myriad Genetics, and for 15 years the company held the exclusive rights to screen and test for BRCA1 and BRCA2 mutations. The tests generally looked for one or the other, or both, excluding many other genes that we now know pose a risk.
In 2013, the Supreme Court ruled that human genes could not be patented, opening the door to easier tests that looked at both BRCA genes as well as mutations in up to 50 cancer-related genes in a single test.
After 2013, costs also dropped, from around $4,000 to less than $400. As a result, testing of both men and women increased steadily over the next decade.
As research has expanded, we now know of at least 11 additional genes linked to increased breast cancer risk besides BRCA1 and BRCA2.
But this list is not exhaustive: dozens of other genes are being studied to see if they increase the risk of breast cancer.
“It’s definitely worth it for someone to get retested, because if you’ve only had tests for BRCA1 and 2, you only have part of the story,” breast cancer researcher Dr. Versha Pleasant told the Washington Post.
Should you get tested for genetic risk of breast cancer?
In the study that showed more than one in six women received a false negative on a genetic test for breast cancer, most only returned for retesting after a family member was diagnosed.
Having a first-degree relative (parent, sibling, or child) with breast cancer almost doubles a woman’s risk of developing it herself.
Family history is one of the most important factors in a standard risk assessment to determine whether you should undergo genetic testing. Ideally, this should be done with a doctor for a homemade risk assessment.
Genetic testing is especially important for those who have already been diagnosed with cancer, as genetic mutations could change treatment plans.
For example, after a test shows a high-risk inherited genetic mutation, a doctor may recommend a mastectomy (removal of all breast tissue) rather than a lumpectomy (removal of the tumor only, preservation of the breast) to reduce the risk of the cancer returning to the single digits.
Additionally, drugs may work well for a certain mutation but not for another. Genetic testing can tell doctors which treatment will work best.
Gn Health
