Colonoscopy Finds Advanced Cancer More Often in Men

WARSAW, Poland, Nov. 2 -- Men are significantly more likely than women to have advanced colorectal cancer detected on colonoscopy screening, suggesting that gender might play a role in how often the procedure should be done.

At all ages from 40 to 66, significantly fewer men than women would need to be screened to pick up one case of advanced colorectal neoplasia, found Jaroslaw Regula, M.D., of the Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology here, and colleagues.

"We found that sex is an independent predictor of the detection of advanced neoplasia during colonoscopic screening," they wrote in the Nov. 2 issue of the New England Journal of Medicine. "Different rates of detection of advanced neoplasia during colonoscopic screening of men and women may warrant a refinement of the screening recommendations to include sex along with age and family history of colorectal cancer."

The findings could have been skewed by gender-based reasons for seeking care or agreeing to undergo colonoscopy, the authors acknowledged.

"Although it is generally accepted that the lifetime risk of colorectal cancer is similar among men and women, the prevalence of advanced neoplasia that is detected during colonoscopic screening has been found to be higher among men than among women," they wrote. "Despite this fact, current recommendations for colorectal-cancer screening do not take sex into account."

They performed a cross-sectional analysis of the data from a large colonoscopy-based screening program that included 50,148 participants from 40 to 66 years old. In all, 32,136 women and 18,012 men took part in the study.

People in their 40s were eligible only if they a family history of any type of cancer, and 66.3% of the 7,106 participants in this age category reported a family history of colorectal cancer. Among the remaining 43,042 participants from the ages of 50 to 66, 13.3% reported a family history of colorectal cancer.

The investigators defined advanced neoplasia as any cancer or adenoma that was least 10 mm in diameter, had high-grade dysplasia, or had villous or tubulovillous histologic characteristics, or any combination.

They looked for associations between patient characteristics and advanced neoplasia using multivariate logistic regression modeling in both a primary analysis and a secondary analysis for validation.

Advanced neoplasia was detected in 5.9% (2,553) of the participants from 50 to 66 years old, and in 3.4% (243) of the participants who were 40 to 49.

The rate of complications during colonoscopy was 0.1%, and there were no deaths.

The modeling indicated the following independent predictors of advanced neoplasia: an age of more than 49, family history of colorectal cancer, and male sex. Hosmer-Lemeshow goodness-of-fit testing of the model in the derivation and validation data sets confirmed its validity.

The authors found in their primary analysis that male gender was independently associated with nearly double the risk for advanced neoplasia (adjusted odds ratio, 1.73, 95% confidence interval, 1.52 to 1.98; P<0.001). After adjustment for colonoscopic factors (presence or absence of cecal intubation and sedation, and adequacy of bowel preparation) as well as for family history and age, the Mantel-Haenszel odds ratios for the detection of advanced neoplasia in men, as compared with women, was 1.98 (95% CI, 1.83 to 2.14).

In addition, for each age group, the analysis showed that the number of men who would need to be screened to detect one case of colorectal cancer was significantly lower than the number of women who would need to undergo colonoscopy. For 40- to 49-year-olds, the ratio was 23 men to 36 women to detect one case. For 50- to 54-year-olds, the ration was 17 to 28, and for 55- to 59-year-olds and 60- to 66-year-olds, the male-to-female ratios were 12 to 22, and 10 to 18, respectively. All differences between men and women in the same age group were significant.

"This finding suggests that the screening recommendations should be modified in order to ensure the maximal diagnostic yield of the screening and the optimal use of resources," the authors wrote. "The numbers needed to screen, as calculated from our data, can be used as a basis for such modifications; however, we did not evaluate the effect of potential changes in screening recommendations on the cost-effectiveness of screening or on the incidence of colorectal cancer or death."

They suggested that screening could be based on a fixed number-needed-to-screen approach. Under such an approach, men 40 to 49 with no family history of cancer, and women 50 to 54 with no family history would both be screened routinely, because the numbers needed to screen are similar between the groups.

"Alternatively, if the recommended age at first screening is 50 years for men, the age for women may be 60 years, because the number needed to screen among women 60 to 66 years old is similar to that among men 50 to 54 years of age," the authors wrote. "Our data also reinforce the recommendation that men who are 40 to 49 years of age and have one first-degree relative older than 60 years of age with colorectal cancer should be screened, since the number needed to screen in this group is as low as 23."

They noted that although both men and women were recruited for the study by their family doctors, women enrolled in the study outnumbered men by a three to two ratio, which could reflect the ratio of patients in private practice who are asked to undergo screening, or could be the result of differences in the way that men and women seek care.

Other studies have shown that women tend to seek medical care sooner and more than men, and "it cannot be ruled out that more men than women entered the program owing to unreported subtle symptoms potentially related to colorectal cancer," they wrote.