I’ll confess: I’m terrified of getting cancer. Again. I’m often reminded by my primary care doctor that cancer is a “disease of aging,” meaning that cancer risk increases dramatically each decade after age 50. Being 60-something puts me in the demographic crosshairs, and my health history compounds my risk. In my twenties I was treated with high-dose chemotherapy for testicular cancer, which created a risk of developing a different form of cancer later on. I’ve got a family history of lung cancer (my mom) and ovarian cancer (my sister), and doctors have spotted several precancerous polyps over the course of regular colonoscopies.
I’ve asked many doctors this same question since my original diagnosis: “How do I reduce my risk?” The answer: Eat more fruits and vegetables, don’t smoke, get regular exercise and guard against too much sun exposure. All valid, but still, I want more. And by that, I mean I want more assurance that some insidious new cancer isn’t already taking root inside my body.
That’s why I’ve been paying close attention to “multi-cancer early detection” screenings, or MCEDs, such as Galleri from the California company Grail. The blood test that says it can detect more than 50 types of cancer took a big step forward last month, when a Food and Drug Administration advisory committee narrowly endorsed it, sending it on to a larger panel for approval. Grail’s chief medical officer, Eric Fung, says this brings the company one step closer to providing routine cancer detection tests at early stages. Earlier diagnosis could lead to more effective and less invasive treatments, with better outcomes.
So why is this test so controversial?
The promise of Galleri and other MCEDs, including Cancerguard and Natera — which was granted “breakthrough” status by the Food and Drug Administration this week — is compelling. A simple blood draw could screen individuals for dozens of cancers, including those for which no routine test exists (such as brain, pancreatic and ovarian cancer). Galleri works by detecting genetic material from cells that could be cancerous, then usually identifies the site of the signal. False positives (detecting a signal when no cancer is present) and false negatives (finding no signal although cancer is present) are possible. These false results could trigger excessive concern in one case, and a false sense of assurance in the other.
Of course, an accurate test that finds cancer at its earliest stages would be a boon for patients, as well as health insurers, which would not have to cover invasive and expensive treatments. Kevin Oeffinger, who directs the Duke Cancer Institute and served as Duke’s principal investigator for the study of Galleri, said in an interview that only about 14 percent of cancers diagnosed right now arise from specific screenings for lung, prostate, colorectal, breast and cervical cancer.
“The vast majority” of these illnesses, he said, “are not diagnosed by some screening protocol but by a patient presenting signs or symptoms.”
That often means later-stage diagnoses, especially pancreatic, ovarian, head and neck, and kidney cancers. Advanced cancers are more complicated to treat, leading to more invasive treatments and a higher rate of deaths.
Still, experts agree that none of the MCED tests currently decrease the chances of dying, which many consider to be cancer prevention’s holy grail.
I was initially ambivalent about getting the blood draw at the Duke Cancer Center, which is one of roughly 30 trial centers for the Galleri blood test. The lengthy intake didn’t help much, since I was alarmed by the answers to my many questions. I could get a false positive? (“You have cancer! Oops, no, the test got it wrong.”) Or a false negative? (“You’re cancer-free. Oops, sorry, you have a malignancy.”) Yes, the staff said.
And what exactly are these cancer “signals” that the test finds? Galleri analyzes circulating cell-free DNA, fragments shed into the bloodstream by tumor cells. Is that a diagnosis? No, they explained, if the test were positive, I’d be sent for further testing, similar to a woman who undergoes a biopsy after a mammogram shows a suspicious spot. Would the test reveal the source of the signal? Usually, they said, prompting scans, more bloodwork and, usually, more anxiety.
I had to ask myself: Was I better off knowing something instead of nothing? And would I actually know anything after this test?
In the months after my sister’s death in 2023, I was driven by cancerphobia as well as a desire to further cancer research. So I decided to join the trial despite my concerns, living with a heightened sense of doom while I awaited the results. Fung said in an interview that he has spoken with “some physicians who have ordered Galleri for their patients but will not take it for themselves for that very reason.”
After the draw, the results popped up in MyChart: No cancer signals detected. (Had the results been different, a nurse practitioner would have called.) I breathed a sigh of relief — but understood that my risk of developing a new cancer remains high.
I dug deeper and discovered that two studies published this year, NHS-Galleri (conducted by Britain’s National Health Service) and Pathfinder 2 (its U.S. counterpart), reported different conclusions about Galleri’s clinical value. The large United Kingdom trial failed to meet its primary goal of reducing Stages 3 and 4 cancer diagnoses for population-level cancer screening, although the overall incidence of Stage 4 cancers was lower among those who took the test.
The U.S. study showed more promising results, demonstrating a fourfold increase in cancer detection when paired with standard-of-care screening such as mammograms and colonoscopies. Two out of 3 cancers were detected in Stages 1 through 3. However, a statistically significant reduction was not seen in combined Stages 3 and 4 diagnoses over three years for 12 deadly cancers. Overall, the U.S. trial found a false positive rate of 0.4 percent, lower than most screening tests, including mammograms.
The study also reported that the test’s ability to predict the origin site of the cancer signal is greater than 90 percent accurate, which can help expedite a diagnosis.
Some researchers are more concerned about false negative results, which could lead an individual to think they’ve gotten a clean bill of health when that is not the case.
For now, the test costs nearly $1,000 and is generally not covered by private insurance or Medicare. If the FDA gives final approval as expected early next year, the Galleri test would be covered by most plans.
Is it worth it?
An ad that ran in this year’s Super Bowl featured a man who checks his phone while in the car. The screen reads, “No cancer signal detected.” He smiles, and then closes his eyes in an expression of relief.
But David Tendler, a gastroenterologist at Duke, said he would not recommend the test to his patients. “The marketing is ahead of the science,” he said. Arthur Caplan, an ethicist and professor emeritus at NYU Grossman School of Medicine, summed it up as “modest benefit, high cost, high risk of misuse.”
I’m glad I took the test, on two different occasions, with no cancer signals having been detected. Since then I’ve had a colonoscopy that found new large precancerous polyps, which were removed. For now, I’m going to keep up with my regular screenings, eating all those darn veggies and watching my steps in the hope of keeping cancer at bay.
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