Findings in the distal and proximal colon in colonoscopy screening after positive FIT and related pre-procedure factors

Abstract

Background: Colonoscopy is the gold standard method for the early diagnosis and prevention of colorectal cancer (CRC). Screening programs include immune determination of blood in faeces. Regardless of the method used, proximal colon lesions appear to be detected less frequently. Objective: analyse the characteristics of proximal and distal lesions and possible predisposing factors. Methods: We made a cross-sectional study of 692 patients from the CRC screening program with FIT ≥ 100ngHb/ml (October 2017 - October 2018). The right colon was examined twice as patients were participating in a randomized clinical trial to re-evaluate the right colon by forward-viewing endoscope or proximal retroflexion. The adenoma detection rate (ADR), advanced neoplasia (AN) and CRC in the proximal and distal colon, the histological and morphological characteristics in each section were analysed. Results: Patients were 52.9% male, a mean age of 59.5 years (SD: 7.6). We found 1490 polyps. The ADR was 57.7% (distal 42% and proximal 37%). Detection rates were 45.8% for AN, 40.9% for advanced adenomas, 5.2% for advanced SSL and CRC was diagnosed in 4.8% of patients. Males had more AN than females. The mean age of patients with AN was significantly higher. AN were associated with smoking and alcohol consumption (p=0.0001). Globally, FIT levels were higher in patients with AN (p=0.003). Sixty-six per cent of cancers were distally located and 61.3% of CRC were diagnosed in the early stages. Conclusions: In an average-risk asymptomatic population undergoing colonoscopy after positive FIT, AN were more common in the distal colon in males, older patients, smokers, and those with alcohol intake.