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In cancer screening, earlier isn’t always better

Medicare shouldn’t be forced to pay for liquid biopsies just yet.

Blood is drawn from a person participating in a clinical trial of liquid biopsy technology at the Oregon Health & Science University's Knight Cancer Institute.Gillian Flaccus/Associated Press

When the two Republican senators from Mississippi cosponsor legislation with the two Democratic senators from California, something intriguing must be going on. In fact, there appears to be an outbreak of bipartisanship: 20 Republicans, 25 Democrats, and one Independent in the Senate are cosponsors, along with a bipartisan majority of 99 Republicans and 134 Democrats in the House.

What do these Republicans and Democrats agree on? That Medicare should be compelled to pay for liquid biopsies, which test for multiple cancers using a single vial of blood, even though no one is sure whether they work or not.


Talk about putting the cart before the horse.

The cosponsors would probably respond that their bill, the Medicare Multi-Cancer Early Detection Screening Coverage Act, would go into effect only if the Food and Drug Administration approves the tests. But unlike with drugs and vaccines, the FDA does not have a particularly high bar for medical tests. The agency’s focus is on the safety of tests, not whether they help people. One liquid biopsy test, CancerSEEK, has already obtained FDA status as a breakthrough device, which signals an expedited review process. Another, Galleri, has avoided the FDA approval process altogether under a waiver for tests that are performed in a single laboratory and are not sold to other labs. Instead, Galleri is being sold directly to consumers at $949 a pop.

The company that sells Galleri recommends that people test once a year. So let’s do the math. Given that there are some 60 million Medicare beneficiaries, that would be approximately $60 billion per year. It would represent a 7 percent increase in total Medicare expenditures ­— to be passed on to taxpayers and/or to Medicare beneficiaries in the form of higher premiums.


All for one test. And no one knows whether that test helps people live longer or live better.

Nonetheless, enthusiasm for cancer screening abounds. As one opinion piece in The Daily Beast put it, “Early Cancer Screening Saves Lives. Congress Needs to Act,” which appears to capture the thinking of more than 400 medical organizations and advocacy groups that support the legislation. They seem to be forgetting the great prostate cancer screening mistake — when men were indiscriminately screened and put through debilitating treatment for a disease that would have killed very few of them.

Advocates of liquid biopsies apparently assume that multi-cancer screening can only help. But screening can hurt people. Some will be overdiagnosed and treated for cancers that would never have otherwise bothered them. Some of these people will be harmed by treatment; a few may even die from it. Others will be found to have advanced cancer at a time when they have no symptoms, yet the earlier detection may have no effect on when they die. These people will be subjected to the toxicities of treatment at a time they would otherwise feel well.

Still others will be told by a liquid biopsy that they have a “cancer signal” — triggering fear and more testing — only to be told later it was a false alarm, because subsequent imaging tests (like a combined PET/CT scan) found no abnormalities. But was it truly a false alarm or does it mean they have a cancer that can’t be found with current technology? Imagine having a cancer signal detected, yet your doctors can’t find the cancer.


There is only one way to know whether a new cancer screening test helps more than it hurts: Perform a randomized trial in which participants are divided into two groups. One gets regularly screened; the other does not. The participants are then followed for a decade or so, counting the number of deaths in each group. It’s the time-honored standard used in tests that screen for breast, colon, lung, and prostate cancer. Such studies have shown, for example, that early screening for lung cancer in heavy smokers does save lives.

The National Cancer Institute is actually planning a randomized trial of liquid biopsy screening now. Ironically, passage of the Medicare Multi-Cancer Early Detection Screening Coverage Act would impede the trial, because of a dynamic we have seen before. In the 1990s, many doctors and patients believed that a transplant of a patient’s own bone marrow was an effective treatment for metastatic breast cancer. Press reports focused on young women dying from aggressive cancer without access to the “lifesaving” procedure. Insurers were sued for not covering it. Fifty-four members of Congress wrote to the Office of Personnel Management demanding that it cover the procedure for federal employees. The presumption of benefit was so strong that investigators had great difficulty finding volunteers to enroll in studies to see if the procedure worked. Everyone already assumed it did.


But it didn’t. Although enrollment was painfully slow, the randomized trials ultimately demonstrated bone marrow transplants didn’t help women live longer. And they most certainly did not live better. Tens of thousands of women were subjected to an arduous procedure often complicated by anemia, infection, and diarrhea. And some died from it.

Liquid biopsy proponents want to bypass the time-honored standard of a randomized trial, which would make clear whether these tests are truly worth doing. They want to bypass review by the US Preventive Services Task Force — the panel authorized by Congress to review the evidence and make recommendations about clinical preventive services like screening. They want multi-cancer liquid biopsy screening to become part of routine medical practice before it is rigorously evaluated. They argue we can’t afford to wait.

In fact, the opposite is true: We can’t afford not to wait. Congress must let the National Cancer Institute and the task force do their work.

H. Gilbert Welch, senior investigator in the Center for Surgery and Public Health at Brigham and Women’s Hospital, is the author of several books, including “Less Medicine, More Health: 7 Assumptions That Drive Too Much Medical Care.”