Colonoscopies Could Prevent 40% of Colorectal Cancers

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Katie Couric was right about colonoscopies. They aren’t fun, but they lower cancer risk and save lives.

After the popular talk-show host underwent a colonoscopy on live TV to raise awareness about the disease that claimed her husband’s life, more Americans underwent the uncomfortable procedure to screen for colorectal tumors. But studies raised questions about how effective the process was in reducing incidence of disease and lowering deaths from the cancer, particular for people with growths in the upper intestines that are generally less accessible by the colonoscopy scope.

But according to the latest results from a Harvard School of Public Health (HSPH) study, 40% of colorectal cancers might be prevented if more people get regular colonoscopy screening, which existing guidelines recommend for those over 50, every 10 years.

In the study, which appears in the New England Journal of Medicine, researchers looked at data from close to 89,000 participants who were a part of either the Nurses’ Health Study or the Health Professionals Follow-up Study, both long-term trials that followed men and women over several decades and recorded a number of health measures. The participants filled out data about their colon cancer screenings with either colonoscopy or sigmoidoscopy, which screens for lesions only in the lower part of the colon, every two years from 1988 to 2008. Overall, there were 1,815 cases of colorectal cancer and 474 deaths.

(MORE: Men May Benefit from Earlier Colonoscopy, but Women Can Wait)

Those getting either procedure had a lower risk of developing cancer or dying from it compared to those were weren’t screened, but only people who had colonoscopies also benefited from fewer cancers in the upper part of the colon, which sigmoidoscopies generally can’t reach. If all of the participants had been screened, the study authors say, they would have developed 40% fewer colon cancers.

The findings are reassuring, since, as TIME reported last year, experts have been debating which type of screening procedure is more accurate and predictive.

(MORE: Cancer Health Special: The Screening Dilemma)

“Each year, more than 1.2 million people are diagnosed with colorectal cancer worldwide. Our findings could help improve and strengthen the current guidelines for colorectal cancer screening,” said lead study author Reiko Nishihara, a research fellow in the Department of Nutrition at HSPH in a statement.

Earlier studies have documented that colonoscopies can reduce the number of colon cancers, but only recently have studies confirmed that the screening, which also involves removal of suspicious growths or tumors, can actually save lives. Now the data supporting the life-saving benefits of colonoscopy looks even stronger.