A major clinical trial found that a blood test designed to detect cancer early did not reduce the number of late-stage diagnoses. Grail, the manufacturer of the test, reported the findings. The results suggest multi-cancer blood tests may not be as effective as anticipated. The Galleri test looks for fragments of DNA associated with cancer. The company says the test can detect more than 50 types of cancer, including mesothelioma. The news is a reminder that this cancer screening technology is still developing and is not yet a proven replacement for standard screening or medical follow-up.
The trial was conducted with the support of the National Health Service in Britain. There were 142,000 healthy adults enrolled who were between the ages of 50 and 77. The test consisted of participants’ blood being drawn three times over a three-year period. One group’s blood samples were tested using the Galleri test. If the person tested positive, they were referred to medical care providers. The trial results showed the use of the Galleri test did not lead to a significant reduction in cancers diagnosed at stage 3 and stage 4. Grail plans to present more detailed results from this trial at a cancer-related conference in the spring. The fact that there was no significant reduction in the number of late-stage cancers is a crucial finding in a trial of this scale.
Numbered stages are used to convey the extent of cancers like mesothelioma in the body. As with other cancers, stages 3 and 4 are late mesothelioma stages. They refer to cancers that have advanced with tumor growth and spread. Stage 3 means the cancer has spread near the site where it first developed. Stage 4 means the cancer has spread to other parts of the body. The trial was designed to show that the blood test would reduce stage 3 and stage 4 diagnoses, but Grail’s own analysis shows that did not happen. Despite this finding, the company’s executives said that the results of the trial indicated the Galleri test still has some benefits. The decrease in the number of stage 4 cancers was cited as being particularly promising. They did not hit their primary endpoint, but what they found still has clinical benefit to it.
Early detection for mesothelioma is difficult because it is a rare cancer without distinct symptoms. Screening tests exist for some cancers, like breast and colon, but not for many other hard-to-treat cancers. The results do not mean that the Galleri test cannot detect cancer early, just that using it did not lead to a significant reduction in Stage 3 and Stage 4 diagnoses. For mesothelioma patients and their families, the Galleri test’s ability to detect more than 50 cancers, including mesothelioma, makes Grail’s more detailed findings this spring worth watching.
The Galleri test has been available in the United States since 2021, but the FDA has not approved it yet. Grail has applied for FDA approval and is seeking Medicare coverage through new legislation. Without insurance coverage, the test costs $949 out of pocket. If a doctor recommends the Galleri blood test to screen for cancer, patients should know it supplements standard screenings rather than replacing them. Doctors do not recommend skipping a colonoscopy or mammogram in favor of using the blood test.
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