Huge trial yields disappointing results on colonoscopy benefits

"Analysis suggests that the screening method cuts risk of colorectal cancer by only a modest amount.

Human colon-cancer cells. A randomized trial failed to show that the screening technique called colonoscopy strongly reduces deaths from colorectal cancer. Credit: Dr Torsten Wittmann/Science Photo Library

Colonoscopies might reduce the risk of colorectal cancer less than expected, according to a landmark trial¹.

One way to screen for colorectal cancer is through colonoscopy, a procedure in which doctors insert a camera inside the big intestine. Colonoscopy is the gold standard for preventing colorectal cancer in the United States, but the procedure’s benefits are unclear.

Michael Bretthauer at the University of Oslo and his colleagues offered colonoscopies to the one-third of their study participants who were randomized to receive such an invitation. The authors followed all 84,500 study participants for 10 years. The researchers found that those offered a colonoscopy were 18% less likely to develop colorectal cancer than those who weren’t.

 

The risk of dying from the disease was roughly the same for both groups.

 

But only 42% of participants who were offered a colonoscopy actually had one. Analysis of that subgroup showed a greater benefit for colonoscopy than was observed for the entire group that received the offer.

 

Even so, the benefit was lower than expected. The researchers say that this could reflect recent improvements in colorectal-cancer survival rates." [1]

1. Nature 610, 423 (2022)