Colonoscopy with polypectomy reduces the incidence of colorectal cancer and its associated mortality. The ideal interval between surveillance examinations is determined by clinical features and endoscopic findings considered as risk factors to the development of advanced colonic neoplasias.
To determine the development rate of advanced neoplasia in patients submitted to surveillance colonoscopy in a tertiary referral center.
Three hundred and ninety two patients who underwent two or more complete colonoscopies between 1995 and 2005, and who have at least one diagnosed colorectal adenoma entered into the study. The endoscopic findings of the first and subsequent colonoscopies of each patient were analysed, considering advanced neoplasia as the main outcome. The patients enrolled were divided in accordance to the first colonoscopy findings in groups 1 or high risk; 2 or low risk; and 3 or without adenoma at the first colonoscopy. The development of advanced colorectal neoplasia and the period of surveillance until the outcome were analysed and compared among groups.
Twenty eight per cent of patients had advanced adenomas at index colonoscopy; 57.8% presented with low grade dysplasia neoplastic lesions and 14.1% had no adenoma at the first examination. The mean age was 59.54 +/- 11.74 years. Twenty six point four per cent of subjects from group 1 presented with advanced neoplasia during the surveillance period, while this outcome occurred in 10.9% and 5.3% of patients from groups 2 and 3, respectively (P<0,05). The mean period of surveillance was 123.35 months, and the mean time between the first examination and the one which presented with the outcome statistically differed among group 1 and the others, being 104.02, 115.31 and 120.61 months, respectively.
Patients with advanced neoplasia at index colonoscopy presented with a higher probability of harbouring this condition during the follow-up when compared with other two groups. These lesions also occur earlier in this patients than in the ones without these lesions at the first examination.