Time trends in first-diagnosis rates of colorectal adenomas: a 24-year population-based study

Little is known about the descriptive epidemiology of colorectal adenomas diagnosed in the population.

To describe time trends in the rate of first diagnosis of colorectal adenomas and estimate the proportion of adenoma-bearing individuals detected over a 24-year period.

A total of 11,027 patients were first-diagnosed with colorectal adenomas among Côte-d'Or residents (France) between 1976 and 1999. Annual percentage changes were estimated using a Poisson regression model. The proportion of diagnosed adenoma-bearing individuals was estimated using the prevalence of adenomas in an autopsy study performed in the area.

Standardized diagnosis rates were 89.6/100,000 men and 50.3/100,000 women. During the period 1976-1993, diagnosis rates significantly increased with annual percentage changes in men and women of respectively +17.1% and +22.3% for proximal adenomas, +7.5% and +9.1% for distal adenomas and +7.2% and +8.0% for advanced adenomas. Changes were less marked during the period 1994-1999. The estimated proportion of adenoma-bearing individuals diagnosed during the 24-year period was 20.0% in men and 16.0% in women.

Despite a marked increase in the rate of first adenoma diagnosis, the proportion of diagnosed adenoma-bearing individuals seems too low to induce a significant decrease in colorectal cancer incidence.