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Myriad Says Study Supports Routine BRCA Testing in Women with Triple-Negative Breast Cancer


Originally published Oct. 5.

Myriad Genetics this week reported preliminary results from a study supporting the hypothesis that BRCA germline mutations occur frequently enough in women with triple-negative breast cancer to justify screening all women in this disease setting.

In a study of 77 women with TNBC, researchers from Myriad Genetics and MD Anderson Cancer Center aimed to characterize the incidence of BRCA mutations within this cancer subtype. According to an abstract of the study, presented this week at the American Society of Clinical Oncology's Breast Cancer Symposium in Washington, DC, the researchers found a 19.5 percent incidence of BRCA mutations in women with TNBC.

In the study, five-year relapse-free survival estimates were 51.7 percent for wild-type patients versus 86.2 percent for mutation carriers, while five-year overall survival estimates were 52.8 percent for wild-type patients versus 73.3 percent for mutation carriers.

"After adjustment for other patient characteristics, patients with BRCA mutations had a significantly better relapse-free survival compared to wild-type patients," the researchers reported in the abstract. "Genetic testing should be discussed with patients with TNBC. Patients with TNBC with BRCA mutations have a significantly lower risk of relapse."

TNBC is particularly difficult to treat because tumors don't express estrogen receptor, progesterone receptor, or HER2. Testing with BRACAnalysis is currently recommended in women diagnosed with TNBC who are under the age of 45 or have family history of disease or other risk factors.

According to Myriad, the study presented at the ASCO meeting this week provides evidence for routine BRCA mutations testing in all women with TNBC, since the 77 participants evaluated in the study did not meet the standard testing criteria, and 43 percent of the mutation carriers in the study — six patients — "would not have qualified for BRACAnalysis testing under existing guidelines," the company noted.

The TNBC setting is a key market where Myriad is looking to expand its flagship BRACAnalysis test. According to Myriad's estimates, TNBC could be a 40,000-patient market opportunity for the test. BRACAnalysis already comprises 90 percent of the company's revenues (PGx Reporter 09/22/10).

"This study confirms the emerging story of the importance of BRACAnalysis testing in triple-negative breast cancer," Mark Capone, President of Myriad Genetic Laboratories, said in a statement. "The high prevalence of BRCA mutations in women that do not currently qualify for BRACAnalysis testing, if confirmed in additional studies, could be considered for future updates to testing guidelines."