A U.S. Food and Drug Administration (FDA) advisory panel voted on Wednesday in favor of a blood test for multiple cancers. The Galleri test is designed to help screen for cancers before symptoms appear, according to its maker, Grail Inc.

The ten-person panel unanimously agreed that Grail showed that the Galleri test is safe, but there was less agreement over whether it was effective and if the benefits of using the test outweigh the risks—six in favor to four against and seven in favor to two against and one panelist abstaining, respectively.

The panel’s favorable vote “represents an important step forward for the field,” says Ajay Goel, a professor and chair of the department of Molecular Diagnostics and Experimental Therapeutics at City of Hope, a cancer research center.

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Ultimately, however, he says that “I would still view it as an encouraging step rather than the final word on the clinical value of this type of testing.”

Some cancer screening tools exist on the market already—including for breast, lung prostate cancer and others—but no multi-cancer early detection tests have been approved by the FDA, according to the American Cancer Society. Having such a test would be clinically useful, enabling doctors to potentially detect a variety of cancers early and affording more time to respond to a diagnosis. Galleri is currently designed for people 50 and over.

The test, experts say, is promising, but not perfect. In a study published on Tuesday in the journal Nature Medicine including more than 35,000 participants, Galleri detected signs of cancer in 287 people, about 60 percent of whom were later diagnosed with the disease. The test was also able to accurately predict what area of the body the cancer originated in about 91 percent of cases.

A negative result, however, Grail has emphasized in its FDA application, does not definitively rule out cancer.

“Galleri has shown that we can detect signals from many different cancers with very high specificity using a simple blood test, including cancers for which we currently have no routine screening,” Goel says. “That is an important advance.”

But the “real goal,” he adds, is not just to find more cancers: “It is to find them early enough to change what happens to the patient.”

“We still need longer term evidence showing that this leads to fewer advanced cancers and ultimately fewer cancer deaths.”

Colin Pritchard, a professor and cancer researcher at the University of Washington, says the Galleri test may be beneficial for people with a high risk of developing cancer, such as those with a family history. But for people with a low cancer risk, false positives could result in unnecessary harms such as expensive imaging or biopsies.

“More research is warranted on which populations should be offered this type of testing and on guidelines for follow up after a positive test result,” Pritchard says.

The FDA considers, but is not required to, follow the advice of its expert panel in making decisions.

If the FDA approves Galleri, Goel says, it should be viewed as “an additional screening tool, not a replacement for established cancer screening.”

This is a breaking news story and will be updated.

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