Current guidelines call for average-risk men and women to begin colorectal cancercancer screening at age 50. Colonoscopy, in which a doctor uses a long, flexible tube to check inside the large intestine, is one method for such screening.
But the new findings, published in Thursday's New England Journal of Medicine, suggest there is a big difference in risk between the sexes at the recommended age.
When researchers in Poland reviewed the results of more than 50,000 colonoscopy screenings conducted in people between the ages of 40 and 66, they found that men had more cancers or large precancerous polyps at earlier ages than women.
The researchers concluded that to maximize the cost effectiveness of screening, men may need to be screened earlier, or women later, than current guidelines suggest.
"If cost is not an issue, then men should probably begin screening a little earlier, maybe at age 40 or 45," researcher Jaroslaw Regula, MD, tells WebMD. "This would be very expensive. But to achieve the same screening value, the recommendations should be different for men and women."
Not a Man's Disease
The lifetime risk for developing the disease is similar for men and women, but women tend to be slightly older when diagnosed, Durado Brooks, MD, tells WebMD.
Brooks, the American Cancer Society's director of prostate and colorectal cancer, says he is concerned that the new findings will be misinterpreted.
"Any explanation of these findings that suggests colorectal cancer is predominantly a man's disease would be a disservice to the public," he says. "That is just not the case."
Brooks also found it troubling that people older than 66 were excluded from the study.
"Colorectal cancer rates continue to rise as people age, and we have a rapidly growing population of people who are 65 and older," he says.
Cancers Appear Later in Women
The new study included about 43,000 people between the ages of 50 and 66 and about 7,000 people between the ages of 40 and 49.
Colorectal cancer or large precancerous polyps were found in 5.9% of the older study participants and 3.4% of those younger than 50.
For each age group examined, significantly more women than men needed to be screened to find one cancer or large polyp. This was true even among people at high risk for developing colorectal cancer because they had a family history of the disease.
"It may not be prudent to exclude from screening men 40 to 49 years of age without a family history of colorectal cancer and, at the same time, include women 50 to 54 years of age without a family history of colorectal cancer, because our data show that these two groups have very similar numbers needed to screen," the researchers write.