Multigene test increasingly used to assess breast cancer risk

More women are foregoing BRCA tests, which only look at the BRCA1 and BRCA2 genes, in favor of more comprehensive genetic testing for breast cancer.
By Brooks Hays  |  May 10, 2018 at 1:25 PM
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May 10 (UPI) -- New research suggests women are increasingly foregoing BRCA tests, which only test for mutations in either of the BRCA1 and BRCA2 genes, opting instead for more comprehensive tests that detect mutations in a larger number of genes.

Because multigene tests can identify a variety of mutations, the risks of which aren't well established, health researchers hypothesized the increase in such tests would lead to an uptick in prophylactic mastectomies -- the removal of both breasts to prevent the development of cancers.

However, the latest survey of breast cancer testing showed changes in test preferences haven't resulted in more mastectomy surgeries.

"In general, multigene panel tests yield more clinically useful results and are rapidly becoming the norm," Dr. Allison Kurian, an associate professor of medicine and of health research and policy at Stanford University, said in a news release. "Newly diagnosed women should ask their doctors whether they may be appropriate candidates for genetic testing."

The findings of Kurian and her colleagues, published Thursday in JAMA Oncology, showed many women are waiting until after tumor removal to undergo genetic testing. This timing could limit their treatment options.

"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," Kurian said.

The researchers surmised the comprehensive tests are sometimes delayed because there are not sufficient resources for their interpretation.

"As genetic testing has become more comprehensive and less expensive, we have begun to see a significant problem in terms of the genetic-counselor workforce," Kurian said. "More genetic counselors are needed, and they should be integrated into routine cancer care."

Unlike BRCA tests, newer, more comprehensive genetic testing can reveal disease-related mutations carried by a patient's unaffected relatives.

"This is very important because it offers the opportunity for genetically targeted, primary cancer prevention in unaffected relatives," Kurian said.

Kurian and her colleagues surveyed women diagnosed with stage 0 through stage 2 breast cancer between 2013 and 2015. The patients were asked about their decision to undergo genetic testing. They were asked which tests they received, as well as who ordered the tests and when.

Only a third of women received genetic testing. At the beginning of the survey, just 26 percent experienced multigene tests. By mid-2015, the number was 66 percent.

The risks of some mutations revealed by multigene tests are poorly understood, particularly for minorities. The authors of the new study argue genetic research needs to include diverse populations to improve the clarity of testing outcomes for minorities.

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