Older BRCA Genetic Tests May Have Missed Cancer-Linked Mutations
Women tested before 2013 may need retesting as scientific understanding and technology have advanced.
Individuals who underwent BRCA genetic testing more than a decade ago may have received results that missed cancer-linked mutations now detectable with modern technology. A recent study indicates that approximately 17.3% of women who initially tested negative for dangerous mutations actually harbored a significant variant when retested, with the retesting occurring an average of five years later.
"There are probably thousands of individuals out there who need to be retested," Dr. Sofia Merajver, a breast cancer researcher, told The Washington Post. Approximately 5% to 10% of breast cancer cases are linked to inherited gene mutations. Current medical recommendations advise all women to complete a risk assessment by age 25 to determine if further genetic testing for cancer-linked BRCA mutations is necessary.
Advancements in Genetic Testing
Historically, testing primarily focused on BRCA1 and BRCA2 genes, which carry the highest risk for breast cancer. These genes were identified in the 1990s, and for about 15 years, a single company held exclusive rights to test for mutations. This limited scope often excluded other genes now known to contribute to cancer risk.
The landscape of genetic testing changed significantly in 2013 after the Supreme Court ruled that human genes could not be patented. This decision opened the door for more comprehensive testing that could examine both BRCA genes and mutations in up to 50 cancer-related genes simultaneously. Concurrently, the cost of testing decreased substantially, dropping from around $4,000 to under $400, which led to a steady increase in testing rates.
Research has since identified at least 11 additional genes linked to an increased risk of breast cancer beyond BRCA1 and BRCA2, with dozens more under investigation. "It's very worthwhile for someone to get retested because if you’ve only been tested for BRCA1 and 2, you only have part of the story," stated Dr. Versha Pleasant, another breast cancer researcher.
Rationale for Retesting
The study highlighting potential missed mutations noted that many women only sought retesting after a family member was diagnosed with cancer. A family history of breast cancer, particularly in a first-degree relative, nearly doubles a woman's risk of developing the disease herself. Family history remains a crucial factor in standard risk assessments for genetic testing.
Genetic testing can also be particularly important for individuals already diagnosed with cancer, as the results can influence treatment plans. For instance, a positive result for a high-risk inherited gene mutation might lead a doctor to recommend a mastectomy instead of a lumpectomy to significantly reduce the risk of recurrence. Furthermore, genetic testing can guide treatment decisions by identifying specific mutations that respond better to certain medications.
