Screening procedure fails to prevent colon cancer deaths, large study finds

Colonoscopy screening exams that are recommended for older U.S. adults failed to reduce the risk of death from colon cancer in a 10-year study that questions the benefits of the common procedure.

While people who underwent the exam were 18% less likely to develop colon cancer, the overall death rate among screened and unscreened people were the same, at about 0.3%, researchers from Poland, Norway and Sweden said Sunday in a study published in the New England Journal of Medicine.

Health experts at the World Health Organization, the U.S. Preventive Services Task Force and other bodies issue recommendations on screening for breast, prostate, colon and other cancers to catch disease in its earliest and most treatable stages. Debate has ensued over the last few years over whether some preventive screenings are helpful in the general population because of possible patient harm and unnecessary treatment, leading to higher health-care costs.

“This relatively small reduction in the risk of colorectal cancer and the non-significant reduction in the risk of death are both surprising and disappointing,” Jason Dominitz, a gastroenterologist at the University of Washington School of Medicine, and Douglas Robertson of the Dartmouth Geisel School of Medicine said in an accompanying commentary. “Additional analyses, including longer follow-up and results from other ongoing comparative effectiveness trials, will help us to fully understand the benefits of this test.”

In a colonoscopy, a long, flexible tube with a tiny video camera is threaded through the rectum into the intestine to look for possible cancerous changes. Doctors sometimes remove polyps and other abnormal tissue using the tube during the procedure. Before the pandemic, more than 15 million colonoscopies were performed each year in the U.S., according to the University of Pennsylvania Abramson Cancer Center.

The American Cancer Society recommends regular colon cancer screening begin at age 45, lowering the age from 50 after noting an increase in these tumors in younger adults. People with a family history of colon cancer or other significant risk factors are recommended to start being screened earlier. Available screening tests range from stool assays that are typically administered annually to colonoscopies that are performed once every 10 years.