What You Should Know
- A panel of experts advising the U.S. Food and Drug Administration (FDA) voted that the benefits of Galleri, a blood test that looks for signs of many cancers at once, outweigh its risks. The FDA hasn’t made its final decision yet.
- Galleri is meant for adults 50 and older who have no signs of cancer. It’s designed to be used alongside regular screenings like mammograms and colonoscopies, not instead of them.
- In studies, the test found about 1 in 3 cancers that people were diagnosed with over the next year. It was much better at finding advanced cancers than early-stage cancers.
On Wednesday, an FDA advisory panel voted on Galleri, a test made by the company Grail. An advisory panel is a group of outside experts the FDA consults for advice before deciding whether to approve a medical product. The FDA doesn’t have to follow the panel’s vote, but it takes it into account.
Read More- 10 to 0 that there’s “reasonable assurance” the test is safe.
- 6 to 4 that it’s effective.
- 7 to 2, with one member abstaining, that its benefits outweigh its risks.
FDA safety approvals will not only bring further legitimacy to the products, but will also come with significant benefits for consumers. While the Galleri test is available for purchase already, FDA approval will enable more robust coverage for the test through other payors and Medicare.
What Is Galleri?
Galleri is a multi-cancer early detection test, or MCED test. That means one blood draw checks for signs of many different cancers. Grail says it can pick up signals from about 50 types.
Here’s how it works:
- Cells release tiny bits of their DNA (the genetic instructions inside every cell) into the blood. This is called cell-free DNA.
- DNA from cancer cells often carries a different pattern of chemical tags, called methylation patterns.
- Galleri looks for those cancer-like patterns.
Why Does That Matter to You?
In theory, it could spot some cancers before you ever feel sick.
If the test finds a signal, the result says “cancer signal detected.” It also guesses where in the body the cancer might be, which is called the cancer signal origin. In the studies, that guess was right about 9 out of 10 times. That helps your doctor know where to look first.
Why This Test Is Getting So Much Attention
Screening means testing people who feel fine to catch cancer early. Right now, routine screening exists for only a handful of cancers, including breast, cervical, colorectal, lung, and prostate cancer.
Many deadly cancers, like pancreatic and liver cancer, have no routine screening at all. According to the FDA, most U.S. cancer deaths come from cancer types that don’t have a recommended screening test. That’s the gap Galleri hopes to help fill.
The test is already available with a doctor’s prescription. It costs around $1,000, and most insurance plans don’t cover it right now. FDA approval could make insurance coverage more likely down the road.
“What remains uncertain is whether finding cancers through this approach will ultimately translate into fewer advanced cancers or fewer cancer deaths. Those are important questions, but they require longer follow-up,” Dr. Garcia said.
Why the Vote Was Close
The 6-to-4 vote on whether the test works tells you something. So does one question the FDA put to the panel: whether the data really support calling Galleri an “early” detection test.
In two large studies, one in the U.S. and Canada and one in England, the test caught roughly 1 in 3 of the cancers people were diagnosed with over the following year.
Stage Matters Here.
A cancer’s stage describes how much it has grown or spread, usually from stage 1 to stage 4. Stage 1 cancers are small and often easier to treat. In the studies, Galleri found stage 3 and 4 cancers far more often than stage 1 cancers.
It also missed most breast and prostate cancers, two of the most common cancers in the U.S.
“People must understand that this does not substitute for other cancer screenings such as mammograms, colonoscopy, or PSA,” a cancer expert told SurvivorNet. A PSA test is a blood test used to check for prostate cancer.
One more detail: the numbers the FDA reviewed came from a newer version of Galleri. That version was tested on blood samples saved from the studies. People in the studies received an earlier version of the test.
False Alarms and False Reassurance
No screening test is perfect, and Galleri can be wrong in two ways.
A false positive means the test says cancer may be there, but follow-up tests don’t find any. In the FDA’s review, somewhere between 2 in 3 and 3 in 4 people with a positive result actually had cancer. The rest got a scare. In the U.S. study, nearly half of the people with a false alarm had an invasive test, such as an endoscopy, to check. An endoscopy is a procedure where a doctor looks inside your body with a thin tube and a camera.
A false negative means the test says no cancer signal was found, but cancer is there. Because Galleri misses many cancers, this is a real concern. Dr. Nitzan Rosenfeld, a cancer researcher at Queen Mary University of London, wrote in an editorial in BJC Reports that people who get a negative result “may be falsely reassured.”
A negative result is not a clean bill of health. If you notice a new symptom, tell your doctor, no matter what the test said.
What the Big Trial In England Found
The NHS-Galleri trial enrolled more than 142,000 people in England, ages 50 to 77. It was a randomized controlled trial, meaning people were randomly assigned to two groups so the results could be fairly compared. It’s considered the strongest kind of study.
One group got the test once a year for three years. The trial’s main goal was to show fewer cancers diagnosed at stage 3 or 4 in that group.
That didn’t happen. “It is disappointing that this goal was not reached,” Rosenfeld wrote.
The tested group did have more cancers found at early stages. There were also somewhat fewer stage 4 cancers, but that difference wasn’t strong enough to be sure it was real.
Finding more early cancers sounds good, and it may be. But researchers still need to learn whether it helps people live longer, or whether some of those cancers would never have caused harm. Results on cancer deaths are expected years from now.
“For me, the potential clinical value of Galleri is not captured by any single sensitivity number. It is the possibility of expanding cancer screening beyond the relatively small number of cancers for which organized screening currently exists, while maintaining very high specificity and providing information that can help guide diagnostic evaluation after a positive result,” Dr. Garcia told SurvivorNet.
“How the test is used will be just as important as the technology itself. Patients need to understand that a positive Galleri result is not a diagnosis of cancer and that a negative result is not an “all clear.” Physicians need to continue established cancer screening and have clear pathways for evaluating a positive result,” Dr. Garcia continued.
What This Means for You
If you’re 50 or older and curious about Galleri, talk with your doctor. Ask what it costs, what happens if the result is positive, and whether it makes sense for you.
And keep up with your regular screenings.
“Think of it as a possible extra layer, not a replacement,” an expert told SurvivotNNet. “The tests we already have save lives.”
The FDA’s final decision is still ahead, and the science is still growing. For now, the most powerful thing you can do hasn’t changed: Stay on schedule with the screenings your doctor recommends.
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