Patient Care

Do Colonoscopies Prevent Colon Cancer?

Oct. 13, 2022
Wilmot Clarifies Contradictory Information from a European Study

Despite some confusing messages this week around the value of colonoscopies, Wilmot Cancer Institute physicians and clinicians across the U.S. say the procedure remains the best and most proven way to detect cancer and prevent colorectal cancer deaths.

The controversy stems from a New England Journal of Medicine article published Oct. 9, 2022, on a large Nordic-European clinical trial.

National news articles covering the study highlighted a finding that colonoscopies only cut the risk of colon cancer by about 18 percent and didn’t substantially reduce deaths — which is far different than previous multiple studies showing that colonoscopy does, in fact, significantly decrease cancer incidence and death. The news articles raised the possibility that the invasive procedure is not worth it.

However, the trial had a major limitation — within the group of study patients who were supposed to get colonoscopies, only 42 percent actually got one.

Not getting screened is obviously going to skew the trial results because a person has to get a colonoscopy to receive the benefits of early detection, said Danielle Marino, M.D., a gastroenterologist with expertise in colon cancer screenings and Medical Director of Wilmot’s Hereditary Cancer Screening and Risk Reduction Program.  

Many news articles glossed over this red flag and made claims in headlines that colonoscopies fail to reduce cancer deaths, ignoring important context, according to the American College of Gastroenterology (ACG).

ACG issued a public statement and sent a terse letter to CNN, which led the news coverage, calling out the media for doing the public a disservice.

“No one should cancel their colonoscopies,” Marino emphasized. “This procedure is the best way to prevent colorectal cancer and to detect cancer early, which can lead to improvement in outcomes.”

Here are some key facts about the study to keep in mind:

  • Among the 42 percent of European study participants who did get colonoscopies, their risk of getting cancer was reduced by 31 percent and the risk of dying from that cancer was 50 percent lower.
  • The quality of the colonoscopies performed by about one-third of the physicians in the European study was below what is considered minimum standards in the U.S., ACG stated.

The European study results show that it’s difficult and complicated to investigate the risks and benefits of cancer screenings across populations in the real world, where many people are reluctant to undergo invasive tests, said Jonathan Friedberg, M.D., M.M.Sc., Wilmot’s director.

There’s no question that colonoscopy finds cancers earlier, he said, but it’s important that clinicians and scientists are open to findings, like in this case, that may point to the need for more research.

In Monroe County, the rates of colon cancer deaths are higher among Black men compared to white men. Wilmot faculty and staff have made significant efforts, with the help of City Council member Willie Lightfoot, to reach out to the community and advocate for screening and early detection.

Colon cancer is the third leading cause of cancer death for men and women. Marino noted that rates of colon cancer are rising in the U.S., particularly because many individuals put off colonoscopies during the Covid-19 pandemic.

It is most often diagnosed in people ages 65 to 74. In the U.S., it is recommended that adults ages 45 to 75 get screened to obtain substantial benefits; younger adults starting at age 40 are also recommended for screening if they have a family history of colorectal cancer or certain medical conditions. Primary care physicians can answer questions about cancer screenings, as well.