In the spring of 2021, the cancer field was abuzz over research that suggested a simple early-detection blood test could find dozens of different cancers, including many for which there is no routine screening.
Four and a half years later, the chatter has only gotten louder: The maker of the test, called Galleri, released new data suggesting its performance had improved.
A number of companies are vying to develop such multi-cancer early-detection blood tests. And though none have been approved by federal regulators — and they cost hundreds of dollars — people are still seeking them out through employers, concierge practices and even major academic centers.
GRAIL, the company that manufactures Galleri, said a total of 420,000 tests had been prescribed thus far, up from 180,000 as of March 31, 2024. The company plans to apply for approval from the Food and Drug Administration next year, and has spent millions lobbying for legislation that would give Medicare the authority to cover the tests.
But despite the demand, there is limited research on the tests’ effectiveness, and whether the benefits outweigh the potential harms — like offering a false sense of security. And the medical field is not yet equipped to make sense of their results, with doctors worried about how to evaluate positive results and unsure whether insurance will pay for follow-up tests.
“It feels like the airplane is being built while flying,” said Cristian Tomasetti, the director of the Centre for Cancer Prevention, Early Detection and Monitoring at City of Hope, a cancer centre in Southern California.
The idea behind early-detection blood tests is simple: When cancer is caught earlier, it is usually easier to treat.
“When you find an early cancer and you can cure it, it is exhilarating,” said Dr Elizabeth O’Donnell, who directs a multi-cancer early-detection clinic at Dana-Farber Cancer Institute in Boston. “You feel like you’ve just done something amazing for someone, especially in a cancer that doesn’t have a screening test.”
William Hill, a 56-year-old firefighter in Brockton, Massachusetts, took a Galleri test last year at a conference for firefighters, who are often exposed on the job to a number of carcinogens.
His blood was sent to a laboratory in North Carolina, where DNA fragments were extracted and analysed for patterns that suggest whether cancer is present and, if so, what type.
Two weeks later, Hill got the result. Cancer signal detected.
“I was hoping it was wrong,” said Hill, who had previously been treated for testicular cancer.
But it was right, he learned, after he went to Dana-Farber for more tests and an abdominal CT scan. They showed metastatic testicular cancer. Immediately, he began treatment.
In retrospect, Hill realised that the back pain and frequent urination he had been experiencing before the blood test were a result of a mass pressing on his kidney. But at the time, he chalked the symptoms up to old age and his job.
It’s hard to say whether getting the test changed his long-term outcome. But Hill credits it with getting treatment started early.
“If I hadn’t had that test, I probably wouldn’t have thought it was cancer,” he said. “I probably would have waited and the mass in my abdomen would have grown even more.”
Cases like Hill’s offer hope. But there is not yet evidence that these tests reduce the risk of death from cancers they find. There is such evidence for breast, cervical, colon and lung cancer screening, and it comes from large, randomised controlled trials that take years.
Studies led by GRAIL and other test makers have supplied the bulk of the evidence so far. In GRAIL’s most recent study, 99 per cent of roughly 23,000 people screened with Galleri got a negative result. Four in 10 of the positive results were later deemed false. The test missed 60 per cent of cancers that went on to be detected within a year, picking up cancer 40 per cent of the time.
Put another way: “They found fewer cancers than they didn’t find,” said Ruth Etzioni, a professor of biostatistics at the Fred Hutch Cancer Centre in Washington State who studies early detection.
Dr Joshua Ofman, the president of GRAIL, said in an interview that the false-positive rate for the Galleri test was far lower than that of some conventional cancer screening tests (0.4 per cent of those tested, compared with about 10 per cent for mammograms, for example). He also said the Galleri test was less likely to pick up slow-growing cancers not likely to cause harm, though currently there appears to be little independent evidence to support that claim.
GRAIL has touted data from its study showing that Galleri detected slightly more than half of cancers at early stages. But that’s similar to how many of the same cancers are found at those stages without the test, said Dr Etzioni, who performed a rough, unpublished analysis of national cancer data for comparison.
New York Times News Service