Blood test that detects 50 types of cancer shows promise in preliminary study

A single blood test that can detect more than 50 types of cancer appears to work quite well in the real world, a preliminary study reveals.

The researchers found that of more than 6,600 apparently healthy people aged 50 and older, the blood test detected a possible “sign” of cancer in about 1%. When those people underwent more extensive testing, cancer was confirmed in 38%.

Experts called the findings an “important first step” in seeing how the so-called multiple cancer screening test might fit into real-world care.

“This is not ready for prime time,” said study co-author Catherine Marinac, a researcher at the Dana-Farber Cancer Institute in Boston.

But if more studies confirm the usefulness of the blood test, he said, it could become a “game changer.”

The findings come from a study called Pathfinder, which is being conducted at various medical institutions across the United States to evaluate Galleri’s blood test. It is one of several blood tests being developed by various companies, all with the goal of providing “one-stop” screening for multiple types of cancer.

Galleri’s test can detect more than 50 types of tumors, including many that currently lack routine screening, such as cancers of the pancreas, liver, and ovary.

But while that may sound like a panacea, there are pitfalls to any cancer screening test. One is the risk of a false-positive result leading to further, possibly invasive, testing, only to find that no cancer is present, and all the anxiety and expense that might accompany that.

It’s important, Marinac said, to study not just how well multiple cancer screening tests work, but what happens when they’re part of real-world care.

And ultimately, he said, a screening test must save lives. Much more research will be needed to show whether the cancers detected by these blood tests are less likely to be fatal.

Galleri’s test is performed by GRAIL, a California biotech company that is funding the Pathfinder study. Galleri and similar tests in development work on a basic premise: They look for biological “signs” that cancer may be present, such as bits of DNA that cancer cells shed into the bloodstream.

Blood tests can also predict where in the body the potential threat is, so doctors can decide which follow-up tests, such as imaging, endoscopy, or biopsy, should be used.

The current findings are based on more than 6,600 adults age 50 and older with no known cancer. Just over 1% tested positive for the Galleri test, and 38% of them were ultimately diagnosed with cancer.

Of all patients with a positive blood test, more than 90% underwent more than one imaging test, while half underwent more than one invasive test, although many of these were performed on people who turned out to have cancer .

The “diagnostic odyssey,” Marinac said, was longer for people who were ultimately not diagnosed with cancer: In those cases, doctors were often hesitant to stop diagnostic workup after initial tests showed no signs of cancer. cancer.

So for those patients, diagnosis “resolution” took a median of 79 days, meaning half had a longer wait.

Importantly, the researchers found that when the blood test indicated no cancer was present, it was correct 99% of the time.

The results were presented Sunday at a meeting of the European Society for Medical Oncology in Paris. Studies published at meetings are generally considered preliminary until published in a peer-reviewed journal.

“This is very exciting technology,” said Dr. Ruth Oratz, a medical oncologist at NYU Langone Perlmutter Cancer Center in New York City.

Oratz, who was not involved in the research, said it would be “fantastic” to detect many types of cancer with a single blood draw. “But,” he emphasized, “we are not there yet.”

Cancer detection is complex, Oratz noted. Depending on their risk factors, some people need to start screening sooner, or have more frequent or different tests, for example.

It’s not yet clear, Marinac said, who should get multiple cancer screening, how often it should be done, or whether the frequency should vary based on people’s risk factors.

Both experts stressed that people should continue existing screening tests for diseases such as breast, cervical and colon cancer.

Talk to your doctor, Oratz said, about what tests you should have.

At this time, the US Food and Drug Administration has not approved any screening tests for multiple cancers. Galleri is available for doctors to order as a “laboratory-developed test,” which the FDA has historically not regulated, according to the US National Cancer Institute.

But patients would likely have to pay for the test, the institute says, and possibly for any diagnostic tests used to follow up on a positive result.

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