Study examines whether age for initial screening colonoscopy should be different for men, women

Although some studies have shown that men are at greater age-specific risk for advanced colorectal neoplasia than women, the age for referring patients to screening colonoscopy for colorectal cancer (CRC) in average-risk patients is 50 years for both men and women because of the increase in the prevalence of CRC in the sixth decade of life. The goal of screening colonoscopy is to find and remove adenomas (polyps, or benign tumors) and particularly advanced adenomas (AAs), according to background information in the article.

Monika Ferlitsch, M.D., of the Austrian Society for Gastroenterology and Hepatology, Vienna, Austria, and colleagues conducted a study to investigate the most appropriate age for initial screening colonoscopy for both male and female patient groups to achieve a higher detection rate of adenoma, AA, and CRC, which could result in a lower CRC mortality rate. The study included 44,350 participants in a national screening colonoscopy program over a 4-year period (2007 to 2010) in Austria. Of the participants, 51 percent were women; the median (midpoint) ages were 60.7 years for women and 60.6 years for men.

The results of the screening colonoscopies included polyps in 34.4 percent (n = 15,267) of the patients, colon cancer in 0.4 percent (n = 162), and rectal cancer in 0.2 percent (n = 92). In 61.4 percent (n = 27,212) of the colonoscopies, no abnormalities were found. Adenomas were found in 19.7 percent of individuals screened, AAs in 6.3 percent, and CRCs in 1.1 percent. The prevalence of adenomas was 24.9 percent for men and 14.8 percent for women; among 50- to 54-year-old men, the prevalence was 18.5 percent, which was greater than the prevalence among women in the same age group (10.7 percent) but similar to the prevalence among 65- to 69-year-old women (17.9 percent). The average number needed to screen (NNS) to detect adenomas were 5.1 for all individuals, 4.0 for men, and 6.7 for women. In 50- to 54-year-old women, NNS was nearly twice as high as in men at the same age (9.3 vs. 5.4). Among 45- to 49-year-old men, NNS was 5.9; a similar NNS of 6.0 was found for women ages 60 to 64 years.

"The prevalence of AAs in 50- to 54-year-old individuals was 5.0 percent in men but 2.9 percent in women; the NNS in men was 20 vs. 34 in women. There was no statistical significance between the prevalence and NNS of AAs in men aged 45 to 49 years compared with women aged 55 to 59 years (3.8 percent vs. 3.9 percent and 26.1 vs. 26," the authors write.

The prevalence of CRC was twice as high among men compared with women (1.5 percent vs. 0.7 percent). A prevalence of 1.2 percent among 65- to 69-year-old women was similar to that in 55-to 59-year-old men (1.3 percent). The researchers found that 55- to 59-year-old men had similar NNS for CRC to that for women who were 10 years older (65-69 years): 75.0 vs. 81.8, respectively.

"In our study, analysis of age- and sex-specific prevalence of adenomas, AAs, and CRC indicates a significantly higher rate of these lesions among men compared with women in all age groups, suggesting that male sex constitutes an independent risk factor for colorectal carcinoma and indicating new sex-specific age recommendations for screening colonoscopy," the authors write.

The researchers note that "deciding whether to adjust the age at which screening begins also requires considering whether the recommended age for women should be older or the recommended age for men younger."

"Further prospective studies are needed to demonstrate the relative clinical effectiveness of screening at different ages."

More information: JAMA. 2011;306[12]:1352-1358.

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