A cancer blood test that aims to catch more than 50 types of cancer before symptoms appear narrowly won the backing of U.S. Food and Drug Administration advisers in September, even as several members of the panel openly doubted that it works. The Washington Post this week told the story of one cancer survivor who says an early catch through a multi-cancer blood test changed his outcome, putting the promise and the uncertainty of the technology in the spotlight.
The test, called Galleri, is made by the biotechnology company Grail. It looks for fragments of DNA in the blood that may signal cancer, and Grail says it can spot cancers of the stomach, bladder, colon, skin and breast, among others, identifying the likely tissue of origin with 93.4 per cent accuracy. It has been sold in the United States since 2021 without FDA approval, costs nearly 1,000 dollars, and is meant for adults aged 50 and older. Grail applied for formal approval in February and stresses the test should not replace standard screenings.
How the cancer blood test won FDA panel backing
The FDA’s 10-member advisory committee voted 6-4 that the test is effective. On whether its benefits outweigh its risks, members voted 7-2, with one abstention, and all agreed the test is safe. Some members said finding cancers that have no screening option today made the test worth backing, but others voted yes with open reservations.
“If we can find more Stage 1 or more early-stage cancers in a population that we can’t screen for currently, then that will end up having benefit,” said committee member Dr Victor van Berkel, division chief of thoracic surgery at the University of Louisville in Kentucky. “But I don’t know that that’s been proven yet. So perhaps my ‘yes’ is a hopeful [vote] rather than an accurate one.”
The evidence gap behind the cancer blood test
Much of the doubt traces to a trial with England’s National Health Service involving more than 140,000 people. The trial’s main goal was to lower the rate of stage 3 and 4 diagnoses across 12 cancers. It did not, Grail announced earlier this year, although full results presented in May showed a 26 per cent reduction in stage IV diagnoses across 12 deadly cancers by the third round of screening. Other research paints a more hopeful picture: in a Grail-funded study published September 22 in Nature Medicine, researchers tested more than 32,000 adults aged 50 and older with no signs of cancer.
The cancer blood test field extends beyond Galleri. Several companies are developing rival multi-cancer early detection tests, and insurers are watching the FDA decision closely: a formal approval could trigger coverage decisions that determine whether the test reaches beyond the wealthy patients who can currently afford its near-1,000-dollar price.
Experts also warn the test can produce false positives, which could cause patients unnecessary anxiety, and false negatives, which may give people false reassurance and discourage them from undergoing recommended screening. Only five cancers currently have established U.S. preventive screening guidelines: breast, cervical, colorectal, prostate and lung. With more than 200 types of cancer and only about 14 per cent of newly diagnosed cancers detected through routine screening, the gap that a cancer blood test could fill is enormous.
What the cancer blood test decision means for patients
The advisory committee’s backing does not amount to FDA approval, which is still pending, and insurance coverage remains an open question. Until regulators rule, the cancer blood test remains a self-pay product sold directly to consumers and through employer wellness programmes. A positive result requires follow-up testing to confirm a diagnosis, and a negative result does not rule out cancer.
For patients and doctors, the dilemma is familiar: adopt a promising tool before its benefit is fully proven, or wait for the definitive trials while cancers go undetected. As the survivor’s story in the Post suggests, for some individuals the bet has already paid off. For the population as a whole, the FDA’s eventual decision will hinge on whether the cancer blood test can convert early signals into saved lives.