Detection of advanced colonic neoplasia in the NHS bowel cancer screening programme and surveillance outcomes in the first six years: are current guidelines overcautious and is it time to change clinical practice?

Abstract

Colorectal cancer (CRC) screening aims to reduce mortality by detecting cancer at an earlier stage. The National Health Service Bowel Cancer Screening Programme (BCSP) offers faecal occult blood screening followed, in positive cases, by colonoscopy to screen for CRC. Participants diagnosed with colorectal adenomas then undergo surveillance according to the British Society of Gastroenterology guidelines.

Data obtained from the BCSP database from June 2006 to June 2012 were studied to evaluate the magnitude of the detection of advanced neoplasia, and identify the predictive factors that influence the presence of carcinoma in adenomas and the proportions of advanced neoplasia detected in different segments of the colon. The outcome of first surveillance procedures was evaluated to assess the validity of the current risk stratification guidelines for BCSP participants. The appropriateness and safety of the time interval used in surveillance for high- (HR) and intermediate-risk (IR) groups were analysed.

The majority of adenomas (59.75%) detected in the BCSP were non-advanced adenomas (NAAs). Advanced neoplastic features were more prevalent in larger adenomas. Increasing size and distal location were significantly associated with the presence of carcinoma in adenomas. The current surveillance strategy is effective in risk-stratifying BCSP participants as the HR group had a significantly higher proportion of adenomas (60.24 vs. 40.14%; P<0.001) at first surveillance; the majority of the IR group did not have any colorectal neoplasia at first surveillance compared to the HR group (59.98 vs. 39.06%; P<0.001). The proportion of HR participants who had their surveillance after one and half years instead of one year, did not demonstrate any increased likelihood of advanced colorectal neoplasia.

Adenoma size and segmental location were the important factors associated with the presence of advanced neoplasia in adenomas. The current guidelines are effective in risk-stratifying BCSP participants; however, the surveillance interval can be safely prolonged for HR and IR patients.