Men tend to develop colon cancer at an earlier age than women, a study found, suggesting that males should start having screening colonoscopies at a younger age than females, researchers from the Austrian Society for Gastroenterology and Hepatology, Vienna, Austria, reported in JAMA (Journal of the American Medical Association). The scientists had gathered data on analysis results of over 40,000 screening colonoscopies. Men were found to have higher rates of advanced tumors than women in all age groups.

Currently, both males and females are screened for colorectal cancer at the age of fifty years, because the prevalence of the disease rises from this age onward. However, some studies had already demonstrated that men develop advanced colorectal neoplasia at an earlier average age than women.

Screening colonoscopies are aimed at detecting and removing adenomas - benign tumors or polyps - as well as advanced adenomas, the authors explained.

Monika Ferlitsch, M.D. and team set out to determine what the ideal age should be for an initial screening colonoscopy for female and male patient groups so that an optimum detection rate of adenomas, advanced adenomas and colorectal cancer could be achieved, resulting in a reduction in the colorectal cancer mortality rate.

Their study involved 44,350 males and females - they took part in a national screening colonoscopy program from 2007 through 2010. Fifty-one per cent of them were female and their median ages were 60.6 years for men and 60.7 for women.

Below are some highlighted results of the screening colonscopies:
  • 15,257 (34.4%) of them had polyps
  • 162 (0.4%) had colon cancer
  • 92 (0.2%) had rectal cancer
  • No abnormalities were found in 27,212 (61.4%) of the colonoscopies
  • 19.7% had adenomas
  • 6.3% had advanced adenomas
  • 24.9% of males had adenomas
  • 14.8% of females had adenomas
  • 1.1% had colorectal cancer
  • 5.1 needed to be screened to detect adenomas (6.7 for females and 4 for males)
  • Among 50 to 54 year-olds, the average number needed to screen was 9.3 in women compared to 5.4 in men
  • Among 45 to 49 year olds NNS (number needed to screen) was 5.9, nearly the same rate as 6 for 60 to 64 year old females
The authors wrote:

"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 colorectal cancer rate among men was over double that of women - 1.5% versus 0.7%. The rate among 65 to 69 year-old females at 1.2% was similar to that of 55 to 59 year-old males at 1.3%.

The researchers wrote:

"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.

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. "

Written by Christian Nordqvist