More women may need breast cancer gene test: U.S. guidelines

Breast cancer prevention with genetics

More women may benefit from gene testing for hereditary breast or ovarian cancer, especially if they’ve already survived cancer once, an influential health group recommended Tuesday.

At issue are genes called BRCA1 and BRCA2. When they’re mutated, the body can’t repair damaged DNA as well, greatly increasing the chances of breast, ovarian and certain other cancers.

Gene testing allows affected women to consider steps to lower their risk, such as when actress Angelina Jolie underwent a preventive mastectomy several years ago.

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Most cancer isn’t caused by BRCA mutations — they account for five per cent to ten per cent of breast cancers and 15 per cent of ovarian cancers — so the gene tests aren’t for everyone. But mutations cluster in families, and the U.S. Preventive Services Task Force has long recommended that doctors screen women who have relatives with BRCA-related cancers and refer those who might benefit from gene testing to a genetic counsellor to help them decide.

Tuesday, the task force expanded that advice, telling primary care doctors they should also assess women’s risk if:

  • They previously were treated for breast or other BRCA-related cancers including ovarian, fallopian tube or peritoneal cancers, and now are considered cancer-free.
  • Their ancestry is prone to BRCA mutations, such as Ashkenazi Jewish women.

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Why screen breast cancer survivors? After all, they already know there’s a risk of recurrence.

Take, for example, someone who had a tumour removed in one breast in their forties a decade ago, when genetic testing wasn’t as common.

Even this many years later, a BRCA test still could reveal if they’re at risk for ovarian cancer — or at higher than usual risk for another tumour in their remaining breast tissue, explained task force member Dr. Carol Mangione of the University of California, Los Angeles. And it could alert their daughters or other relatives to a potential shared risk.

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“It’s important to test those people now,” Mangione said. “We need to get the word out to primary care doctors to do this assessment and to make the referrals.”

Private insurers follow task force recommendations on what preventive care to cover, some at no out-of-pocket cost under rules from former President Barack Obama’s healthcare law. The recommendations were published in the Journal of the American Medical Association.

Cancer groups have similar recommendations for BRCA testing, and increasingly urge that the newly diagnosed be tested, too, because the inherited risk can impact choices about surgery and other treatment.

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Identifying BRCA mutation carriers “can be lifesaving, and should be a part of routine medical care,” Drs. Susan Domchek of the University of Pennsylvania and Mark Robson of Memorial Sloan Kettering Cancer Center, who weren’t involved with the new guidelines, wrote in an editorial accompanying them.

But too few high-risk women ever learn if they harbour BRCA mutations, they wrote. For example, cancer groups have long recommended that all ovarian cancer patients be tested, but several studies have found testing is done in less than a third.

Don’t skip the genetic counselling, said the task force’s Mangione. BRCA testing can cause anxiety and sometimes gives confusing results, finding mutations that might not be dangerous — things the counselors are trained to interpret. There’s a shortage of genetic counselors, particularly in rural areas, and she said counselling by phone can work.

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There’s a wide array of gene tests, some that search just for BRCA mutations and others that test dozens of additional genes at the same time.

There’s even a direct-to-consumer kit sold by 23andMe — but Domchek and Robson warned it only detects the three mutations found most in women of Ashkenazi Jewish descent, not dozens of other mutations.

© 2019 The Canadian Press

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