At-home DNA breast cancer test may not offer ‘full risk picture’


A warning from doctors after the Federal Drug Administration cleared the way for a genetic testing company to offer over-the-counter breast cancer screening kits.

The 23 and Me tests are the first-ever at-home DNA exam that checks for three cancer-causing gene mutations.

But doctors say results may not give women the full picture of their cancer risk.

Last week, doctors removed Catrina Edwards’s ovaries. A full genetic screening at Texas Oncology in Austin revealed she has a high-risk for breast and ovarian cancers. She saw the link in her family tree.

“My dad has prostate cancer,” she said. “He had thyroid cancer. He had leukemia and his mother died of ovarian and uterine cancer.”

Edwards said she considered a double mastectomy to get rid of the breast cancer risk, but her insurance wouldn’t pay for the surgery. Now, she closely watches for signs of the disease. But the driving force behind her decision: her daughter is expecting a little girl this summer.

“I have to stick around. I want to see her,” she said. “Knowing early helps, because, there are so many things that they can do to help them. And my daughter will be able to be proactive before her next pregnancy.”

Many women will soon have access to that DNA information with a quick swab and a $199 fee to 23 and Me, a DNA testing firm. The company is set to offer results of cancer-causing mutations found on the BRCA 1 and BRCA 2 genes, they are the best-known genes linked to the disease.

This week, the FDA approved a request from 23 and Me to offer the spit tests.

But doctors warn the over-the-counter option only looks at three specific spots on those genes, when there are at least 1,000 other known mutations.

“If you imagine spell-checking a book and you say, ‘well the word “color” tends to be misspelled. So, we’re just going to look for “color” through the book but we’re not going to spell check the whole book,’” she said. “If you spell-check the whole book, we’re going to find those misspellings or those mutations. But, we’re also going to find everything else.”

Texas Oncology Nurse Practitioner Elisabeth King said something will probably go missing. It is why she counsels women to get comprehensive DNA screening, in addition to the at-home test. Plus, she said even if results come back all clear, it doesn’t always mean that is the case.

“About half the patients we follow for high-risk actually have negative genetic testing,” King said. “But they still have this concerning family history that we can’t explain. We’re still worried about you even though we haven’t found the thing causing all of the cancer in your family.”

Doctors say women most at risk of developing such cancers found on those genes are of Eastern European Jewish descent. But experts report women of other genetic backgrounds can also be affected.

Copyright 2021 Nexstar Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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