May 6, 2023. Last September Lead From Behind, an organization founded to “get the word out that colon cancer is preventable,” released a video starring Ryan Reynolds and Rob McElhenney. The wise-cracking actors, both 45 and in good health, reveal that they have undergone colonoscopies, during which a physician snakes a tube more than a meter long up your butt to look for suspicious growths, or polyps.

Physicians detected and removed polyps during both actors’ colonoscopies. Gastroenterologist Jon LaPook, who performed Reynolds’ colonoscopy, says it was “potentially life-saving.” LaPook, a medical correspondent for CBS News, says colonoscopy “saves lives, pure and simple.” Lead from Behind (yes, “Behind” is a double entendre) urges viewers 45 or older to “help Rob and Ryan kick colon cancer’s ass” by getting a colonoscopy.

Weeks later, leaders of the most rigorous study of colonoscopy to date, NordICC, reported finding no evidence that colonoscopy saves lives. LaPook, discussing the study on CBS News, reiterated his faith in colonoscopy. But an editorial in the prestigious New England Journal of Medicine, which published the NordICC study, called it “surprising and disappointing.”

Before I delve into the colonoscopy study, some background: The National Cancer Institute estimates that 52,500 Americans will die of colorectal cancer in 2023. That makes colorectal cancer the second deadliest cancer, behind only lung cancer, which is expected to kill 127,070 people this year. The risk of colorectal cancer, like most cancers, rises with age. In 2021 a federal task force recommended screening asymptomatic people 45 and older with colonoscopy or other methods, such as examining feces for blood.

A selling point of colonoscopy is that it can detect and remove growths in a single procedure. A tube equipped with a camera is inserted into the rectum and colon; if the camera finds a suspicious polyp, a surgical device slices it off and retrieves it for biopsy. Colonoscopy’s popularity has surged over the last several decades; more than 15 million Americans were being screened a year before the Covid-19 pandemic, according to one estimate.

Past studies suggest that colonoscopy reduces your risk of dying from colorectal cancer by anywhere from 29 to 88 percent. But these studies might reflect self-selection bias: people who get a colonoscopy might be healthier and hence less prone to colon cancer than people who don’t. Randomized trials avoid self-selection bias by assigning people at random to two groups: one receives the intervention in question, and the control group doesn’t.

NordICC, for Nordic-European Initiative on Colorectal Cancer, is the first large-scale, randomized trial of colonoscopy. The study focused on 84,585 men and women 55-64 years old in Sweden, Norway, Poland and the Netherlands. The researchers randomly divided subjects into two groups: one invited to get a colonoscopy, the other not. 

NordICC measured rates of death from colon cancer and from any cause in these two groups after 10 years. Some researchers favor “all-cause” mortality, because tests and treatments for a specific cancer can result in deaths unattributed to that cancer.

Colonoscopy can cause perforation of the colon, bleeding and infection; patients may also have adverse reactions to purging of the bowels and sedation. A 2016 study of 331,880 people who underwent colonoscopies found that 1.6 percent had complications serious enough to require “unplanned hospital visits” within one week. 

NordICC found that the risk of death from colon cancer after 10 years was 0.28 percent in the invited group and 0.31 percent in the control group. The difference in risk of death from any cause was even smaller: 11.03 percent in the invited group and 11.04 percent in the uninvited group. These are not statistically significant differences.

Defenders of colonoscopy seize on the fact that only 42 percent of the NordICC subjects invited to get a colonoscopy actually got it; this group’s mortality rate from colon cancer was 0.15, significantly less than the control rate of 0.31. The Colon Cancer Coalition says this finding confirms that “colonoscopy saves lives.” But this lower mortality rate might reflect self-selection bias, precisely what NordICC was designed to overcome.

Think of the NordICC results this way: You’re the health czar of America, with limited funds to invest in public-health programs. Should you offer colonoscopy to everyone 45 and over, whether or not they have risk factors for colorectal cancer? The NordICC findings suggest that investing in such a program would be dumb, because it would not extend Americans’ lives.

Colonoscopies are expensive, too. Costs in the U.S. vary from under $1,000 to more than $27,000, according to a recent study, and average about $3,000. Costs can be unpredictable, going up if polyps are removed and if complications ensue. If 15 million Americans a year undergo colonoscopy at $3,000 a pop, that comes to $45 billion a year.

Clearly, colonoscopy is a lucrative business, as is the treatment of colorectal cancer. Keep that in mind when you encounter pitches for colonoscopy. Lead from Behind, which produced the Reynolds/McElhenney video, is associated with the Colorectal Cancer Alliance, which is supported by biomedical companies that market cancer-related products. When examining dubious scientific claims, I tell my science-writing students, follow the money.

A few more points: Lead from Behind says “roughly 1 in 3 people has a polyp in their gut by their 45th birthday.” This claim is meant to frighten people into getting colonoscopies. But the one-in-three statistic tells me that most polyps—including, I’m guessing, the ones found in Ryan Reynolds and Rob McElhenney—are harmless.

Proponents of colonoscopies credit them with recent declines in mortality from colon cancer. But the declines parallel decreases in smoking, a risk factor for colorectal cancer. Other risk factors include consumption of alcohol, obesity, a sedentary lifestyle and a family history of the disease. Pain in your abdomen and blood in your poop are also symptoms of colon cancer--and of many other disorders.

The FDA has approved tests, such as Cologuard, that examine feces for blood and other possible signs of colorectal cancer. These tests are cheap and non-invasive, but they have high false-positive rates. The recommended follow-up to a positive stool test is, you guessed it, colonoscopy.

On the newsletter Sensible Medicine, physicians John Mandrola and Vinay Prasad say the “stunning” NordICC results should have “immediate influence on decisions regarding screening programs and individual choices.” They suggest that people at risk of colorectal cancer get screened with sigmoidoscopy, which examines a shorter section of the colon than colonoscopy.

Advocates of colonoscopy pooh-pooh sigmoidoscopy, comparing it to a mammogram that examines only one breast; but sigmoidoscopy is cheaper and less intrusive than colonoscopy and its benefits better established, according to Mandrola and Prasad.

Let me return for a moment to the comment, quoted above, that the NordICC results are “surprising and disappointing.” The results are certainly disappointing to physicians and hospitals who benefit from administering colonoscopies and providing follow-up care. But surprising? Come on. 

As I’ve argued here and here, the cancer industry’s aggressive promotion of screening for asymptomatic people has unleashed an epidemic of traumatic, costly overdiagnosis. Overdiagnosis, which occurs when a harmless polyp or other anomaly is flagged as cancerous or potentially cancerous, results in unnecessary surgery, radiation and chemotherapy.

The U.S. cancer industry suffers from a massive case of what economists call the expert service problem. The problem arises when experts whom we trust to take care of our cars or bodies have a financial incentive to find things wrong with us. I wish Ryan Reynolds and Rob McElhenney would make a video about that.

Further Reading:

Physicians John Mandrola and Vinay Prasad offer an excellent analysis of the NordICC results on Sensible Medicine. See also Prasad’s video on the NordIIC trial, which is just as entertaining as the Reynolds/McElhenney video and much more factual.

See also my previous columns on cancer: The Cancer Industry: Hype Versus Reality and We’re Too Scared of Skin Cancer.