Flexible sigmoidoscopy or colonoscopy as a screening modality for colorectal adenomas in older age groups? Findings in a cohort of the normal population aged 63-72 years

Background-Most cases of colorectal cancer originate from adenomas. Removin g adenomas has been shown to reduce the incidence of colorectal cancer. The design of cost effective endoscopic screening programmes requires a knowle dge of the distribution of adenomas in different age groups. Aim-To investigate the distribution of colorectal adenomas in older age gro ups in the normal population. Method-A total of 356 men and women selected randomly from the population r egister were offered a colonoscopic screening examination to detect and rem ove polyps. Results-In all, 241 (68%) subjects, mean age 67.4 years (range 62-73), atte nded. The caecum was intubated in 193 (80%), and in this group 32 (38%) wom en and 51 (47%) men had adenomas. One hundred and ten (54%) of the adenomas and 11 (39%) of the "high risk adenomas" (adenomas larger than 10 mm in di ameter, adenomas containing villous components, and adenomas with severe dy splasia) were found proximal to the sigmoid colon. In 36 (43%) of the subje cts with adenomas, the adenomas were only found proximal to the sigmoid col on. Twenty two (11%) subjects had more than two adenomas. Of 203 adenomas d iscovered, 189 (93%) were less than 10 non in diameter. Conclusion-More than half of the adenomas were localised proximal to the si gmoid colon, and, in nearly half of the adenoma bearing subjects examined, the adenoma was proximal to the descending colon. This indicates that a sig moidoscopic screening examination in this age group would miss a substantia l number of adenomas, but this may be acceptable as the vast majority of pr oximal adenomas db not progress to clinical cancer within the life expectan cy of this age group.