A landmark study suggests colonoscopies are not as effective as previously thought, though they can still help some.
The study, published in The New England Journal of Medicine, followed more than 84,000 people. Half of participants were invited to have a colonoscopy. Only 42 percent did.
After a ten-year follow-up, researchers found an 18 percent risk reduction for those who underwent a colonoscopy and a 50 percent reduction in risk of dying from colorectal cancer.
However, 50 percent is "on the low end" of the medical community's expectations, lead researcher and gastroenterologist Michael Bretthauer, MD, told CNN. "We may have oversold the message for the last 10 years or so, and we have to wind it back a little."
Some experts say the findings shouldn't discourage people from getting a colonoscopy.
"I think it's just hard to know the value of a screening test when the majority of people in the screening didn't get it done," William Dahut, MD, chief scientific officer at the American Cancer Society, told CNN.