Risk of advanced colorectal neoplasia according to age and gender.

Colorectal cancer (CRC) is one of the leading causes of cancer
related morbidity and death. Despite the fact that the mean age at
diagnosis of CRC is lower in men, screening by colonoscopy or fecal
occult blood test (FOBT) is initiated at same age in both genders.
The prevalence of the common CRC precursor lesion, advanced
adenoma, is well documented only in the screening population. The
purpose of this study was to assess the risk of advanced adenoma at
ages below screening age. We analyzed data from a census of 625,918
outpatient colonoscopies performed in adults in Bavaria between
2006 and 2008. A logistic regression model to determine gender- and
age-specific risk of advanced neoplasia was developed. Advanced
neoplasia was found in 16,740 women (4.6%) and 22,684 men (8.6%).
Male sex was associated with an overall increased risk of advanced
neoplasia (odds ratio 1.95; 95% confidence interval, CI, 1.91 to
2.00). At any age and in any indication group, more colonoscopies
were needed in women than in men to detect advanced adenoma or
cancer. At age 75 14.8 (95% CI, 14.4-15.2) screening, 18.2 (95% CI,
17.7-18.7) diagnostic, and 7.9 (95% CI, 7.6-8.2) colonoscopies to
follow up on a positive FOBT (FOBT colonoscopies) were needed to
find advanced adenoma in women. At age 50 39.0 (95% CI, 38.0-40.0)
diagnostic, and 16.3 (95% CI, 15.7-16.9) FOBT colonoscopies were
needed. Comparable numbers were reached 20 and 10 years earlier in
men than in women, respectively. At any age and independent of the
indication for colonoscopy, men are at higher risk of having
advanced neoplasia diagnosed upon colonoscopy than women. This
suggests that starting screening earlier in life in men than in
women might result in a relevant increase in the detection of
asymptomatic preneoplastic and neoplastic colonic lesions.