Could saliva tests become the future of diagnosis? : NPR

Your saliva is “like a microbial fingerprint,” says Purnima Kumar, a spokeswoman for the American Dental Association. But it also changes if you take a sip of water or coffee.

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The saliva that flows through your mouth contains a wealth of microbial information about the rest of your body and is easier to collect than blood samples. Today, a few drops of sputum can help detect viruses like HIV and the one that causes COVID-19, or assess genetic risks for breast cancer.

Within a few years, experts say, similar tests could be available to diagnose other diseases, such as diabetes or prostate cancer.

“It would be great to treat preventatively rather than reactively,” says Wallace Bellamy, a dentist in Sacramento, Calif., and president of the National Dental Association, which promotes health equity.

He says that if saliva tests become commonplace in dental care, they could help save lives and money by detecting diseases earlier. But they are not widely used because they are expensive.

“Insurance is a key factor here. Most of our patients want to know if they’re covered by insurance, and they’re not,” says Bellamy, who has no financial interest in the companies that offer the tests.

Currently available tests performed at home or at the dentist’s office cost between $100 and $200, and samples are usually mailed back to the lab that developed them for analysis. Bellamy doesn’t offer the tests in his office to his dental patients, but if one of his patients takes one he ordered online, he likes to know the results.

Limited FDA approval

The tests can be very accurate in detecting cavities or oral cancer, for example.

These tests are created by specific laboratories approved by the Centers for Disease Control and Prevention, but they are not approved by the Food and Drug Administration (FDA), which requires exhaustive reliability studies.

Most companies operating without FDA approval are like OrisDX, a Chicago-based company that plans to start selling a test in April that can detect squamous cell cancers of the head and neck with 93% reliability, CEO Harald Steltzer said. Patient samples will be collected, either in a dentist’s office or via dental telehealth, and will then be sent back to a specific laboratory for processing.

“There’s a big unmet need,” Steltzer says. Otherwise, he says, “we still look for cancer like we did 100 years ago, which is visual inspection of the oral cavity and tactile sensation around the chin and glands.”

To date, the only diagnostic saliva tests approved by the FDA are those to detect HIV and COVID-19.

New incentives

Some companies are seeking FDA approval for tests to diagnose various types of cancers, including mouth and throat cancers — and now there’s a new financial incentive to do so, too.

As part of its recent spending bill, Congress required Medicare to cover FDA-approved multicancer detection, whether it uses blood, saliva or other means, says Sheila Walcoff, a regulatory consultant and CEO of Goldbug Strategies.

That means that once these tests are approved by the FDA, Medicare — as well as other private insurers likely to follow Medicare’s lead — will cover the costs, she says, making it worth the effort for companies to invest in getting full FDA approval.

“Now that there’s a carrot for them to get immediate national reimbursement for these tests, that’s really going to move them forward,” Walcoff says.

Always on the move

One challenge is that saliva is more difficult to test than blood because it is always moving. It changes after brushing, drinking, eating or smoking, for example, and its composition differs in different people, says Purnima Kumar, chair of periodontics and oral health at the University of Michigan and a spokesperson for the American Dental Association.

“There’s a lot of variability,” says Kumar. “They’re like a microbial fingerprint for you.”

Researchers are now trying to identify specific salivary markers that can reliably identify the disease in diverse populations, Kumar says.

If they succeed, Kumar hopes the saliva tests will help reduce barriers to care. In her own practice, for example, she uses at-home saliva tests to monitor infections after oral surgery, particularly in patients who live in rural areas, are elderly, or lack transportation. The results can be read by the patient and reported to the doctor, who can prescribe additional medications if necessary.

Kumar says that while the availability and reliability of these tests are improving, they should not replace in-person care or dental visits. Just as blood tests help identify problems with cholesterol or liver disease, saliva tests could become another way for busy people to keep tabs on their health, potentially during a visit to the dentist. She says it’s like a health alert system that could warn people, “Hey, something’s wrong with you, go get help.” »