To derive age and sex specific estimates of transition rates from advanced adenomas to colorectal cancer by combining data of a nationwide screening colonoscopy registry and national data on colorectal cancer (CRC) incidence.Registry based study.National screening colonoscopy programme in Germany.Participants of screening colonoscopy in 2003 and 2004 (n = 840,149).Advanced adenoma prevalence, colorectal cancer incidence, annual and 10 year cumulative risk of developing CRC among carriers of advanced adenomas according to sex and age (range 55-80+ years)The age gradient is much stronger for CRC incidence than for advanced adenoma prevalence. As a result, projected annual transition rates from advanced adenomas to CRC strongly increase with age (from 2.6% in age group 55-59 years to 5.6% in age group >or=80 years among women, and from 2.6% in age group 55-59 years to 5.1% in age group >or=80 years among men). Projections of 10 year cumulative risk increase from 25.4% at age 55 years to 42.9% at age 80 years in women, and from 25.2% at age 55 years to 39.7% at age 80 years in men.Advanced adenoma transition rates are similar in both sexes, but there is a strong age gradient for both sexes. Our estimates of transition rates in older age groups are in line with previous estimates derived from small case series in the pre-colonoscopy era independent of age. However, our projections for younger age groups are considerably lower. These findings may have important implications for the design of CRC screening programmes.

Risk of progression of advanced adenomas to colorectal cancer by age and sex: estimates based on 840 149 screening colonoscopies