Ongoing and increasing evidence suggest that an equivalent rate of mutations may be found regardless of whether patients meet current testing criteria, according to a large group of community breast physicians. They presented their findings on Friday, December 8, during a poster session at the San Antonio Breast Cancer Symposium.
Although emerging research indicates that the rate of pathogenic mutations is higher than originally suspected in the general population, few studies have examined the broad use of genetic testing in patients who present to breast practices, the researchers said. As a result, those referred for risk assessment are generally those who have a perceived higher risk or who already have a diagnosis of breast cancer. Traditionally, National Comprehensive Cancer Network (NCCN) guidelines have been the primary reference for patient selection.
In this analysis, 13 community-based breast physicians experienced in cancer genetic risk assessment and testing identified candidates based on perceived and actual risks for hereditary breast cancer. A single test price was used to eliminate cost as a variable in panel selection.
A total of 226 patients were tested; patients met NCCN guidelines as reported by their physician 65% of the time. The majority of patients (77%) were tested for more than 14 genes. A recent diagnosis of breast cancer was reported for 139 (61.5%) of patients. Overall, 13.9% had a pathogenic mutation. The most common positive findings were BRCA1, BRCA2, CHEK2, and MUTYH. Among patients who met NCCN criteria for testing, 12.2% had pathogenic mutations (50.0% of which were in BRCA1 or 2), whereas 11.1% of the patients who did not meet NCCN criteria had pathogenic mutations (28.6% of which were in BRCA1 or 2). Patient age did not greatly affect outcomes: 13.5% of those younger than 50 years had pathogenic mutations compared to 12.3% of those older than 50. However, a substantially larger percentage of patients younger than 50 had BRCA1 or 2 mutations (53.3% versus 40.0%).
The group hopes to enroll 1,000 patients to confirm findings that non-NCCN criteria patients had a lower incidence of the most common mutations (BRCA1 or 2) but still had actionable mutations.