Study: Men May Benefit from Earlier Colonoscopy, But Women Can Wait

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Colonoscopies aren’t the most pleasant medical procedures around, but regular colon-cancer screening can potentially save your life. That’s why doctors and most professional medical organizations recommend that all men and women start getting colonoscopy screenings at age 50. But now researchers from Vienna, Austria, report that colon tumors develop more often and earlier in men than in women, suggesting that the blanket screening guidelines should be reconsidered.

Led by Dr. Monika Ferlitsch, an associate professor of medicine at the Medical University of Vienna, researchers analyzed colonoscopy screening results for 44,350 participants over a four-year period. The research team recorded all abnormal lesions, including adenomas, which are colon polyps that can become malignant, advanced adenomas, and colorectal cancers.

Men were nearly twice as likely as women to have each of the three aberrant types of growths. Researchers found that 25% of men had adenomas, for example, versus 15% of women. Likewise, about 1.5% of men had colon cancer, compared with 0.7% of women.

When they looked at the breakdown of these growths by age, Ferlitsch and her colleagues found that men started developing them long before women did. For example, 3.8% of men aged 45 to 49 had advanced adenomas, but a similar rate wasn’t seen in women (3.9%) until age 55 to 59.

“At the age group we recommend that screening start, between 50 and 55, the incidence of advanced adenomas was twice as high in men [5%] as in women [2.9%],” says Ferlitsch. “And when we compare age groups to find comparable incidence of advanced adenomas, it’s 45 to 49 years for men and 55 to 59 years for women, a gap of about 10 years.”

If colon cancer lags about a decade in women, does that mean men should start getting screened earlier? Ferlitsch and her team calculated an important statistic for determining screening guidelines — the number needed to screen. This refers to how many patients would need to have colonoscopies in order to detect one colon cancer. Because there aren’t strong data to support what this number should be, Ferlitsch’s team used a reasonable number of 26, which isn’t far from the number needed to screen that supports the current recommendation for screening at age 50.

Based on this number, she says more colon cancers might be detected among men if screening began at age 45, while women may not need to start screening until they are 55. At age 50 to 54, the data suggest, the number needed to screen is 20 in men, but 34 in women.

Ferlitsch’s study isn’t the first to find different rates of colon cancers between men and women, or between other groups. There are guidelines in place that already take into account the higher rate of cancer among African Americans, for example. The American Gastroenterology Association advises that African Americans start regular screenings at age 45, based on studies that show they are 23% more likely than whites to develop polyps at that age.

“Our paper is another that underlines the need for changing the recommendations,” says Ferlitsch. “We really don’t know exactly how to do that at this time, whether men should be screened earlier and women should continue to be screened starting at age 50, or whether there should be changes for both men and women.”

The current guidelines to start routine screening at 50 are based on data that show rates of colon cancer start to peak at age 60. Since these tumors take about a decade to develop, experts think it makes sense to start looking for the first signs of malignancies at age 50. But as the latest data show, that advice may not have accounted for some gender differences in the way colon cancers arise.

The new study was published in the Journal of the American Medical Association.

Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.

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