Multigene testing replacing BRCA tests for breast cancer risk

The use of genetic tests aimed at detecting the presence of mutations in the BRCA1 and BRCA2 genes in women with breast cancer is rapidly declining in favour of tests that can detect multiple cancer-associated mutations, according to researchers at the Stanford University School of Medicine and five other U.S. medical centres.
Some researchers had wondered whether multigene testing, which may identify genetic mutations of uncertain clinical significance, would lead more women to consider prophylactic mastectomies — a surgery in which both breasts are removed to prevent future cancers — out of an abundance of caution. However, the current study did not show an increase in mastectomies associated with testing more genes. 
The shift reflects a growing acknowledgement by clinicians that multigene panel tests can yield more clinically useful information for patients and their unaffected relatives, the researchers said.
Overall, multigene panels were about twice as likely as the tests for BRCA1 and BRCA2 to identify disease-associated genetic variants, the study found. However, multigene testing was more likely than the BRCA-only testing to be delayed until after surgery to remove the tumour. This time lag may limit a patient’s treatment options, the researchers said.
 “In general, multigene panel tests yield more clinically useful results and are rapidly becoming the norm,” said Allison Kurian, MD, associate professor of medicine and of health research and policy at Stanford. “Newly diagnosed women should ask their doctors whether they may be appropriate candidates for genetic testing. They should also advocate for the opportunity to discuss genetic testing and its implications with an experienced clinician, such as a genetic counselor, in a timely manner.”
In general, multigene panel tests yield more clinically useful results and are rapidly becoming the norm.
Multigene panel tests are more likely than BRCA-only tests to yield information about both a patient and her family members, who may be unwitting carriers of disease-associated mutations. “This is very important because it offers the opportunity for genetically targeted, primary cancer prevention in unaffected relatives,” said Kurian, who is a member of the Stanford Cancer Institute. “Some prior research has shown that this ‘cascade testing’ of unaffected relatives is cost-effective, and there are currently several initiatives underway to improve upon the delivery and success rates of cascade testing.”

Stanford School of Medicine
med.stanford.edu/news/all-news/2018/05/multigene-testing-replacing-brca-tests-for-breast-cancer-risk.html