Detection and management of colorectal neoplasia in the NHS bowel cancer screening programme

Abstract

Background Screening for colorectal cancer aims to reduce mortality by detecting cancer at an earlier stage. The NHS Bowel Cancer Screening Programme (BCSP) offers faecal occult blood testing (FOBt) followed by colonoscopy for those with a positive FOBt. This thesis examines the detection and management of colorectal neoplasia in the BCSP. Aims and Methods 1. Explore adenoma detection rate (ADR) as a measure of colonoscopic performance and examine which factors influence adenoma detection rate by analysing data gathered from the BCSP. 2. Describe the findings at 12 month surveillance colonoscopy in high risk individuals (according to adenoma surveillance guidelines in the BCSP) and explore factors which may predict findings at surveillance. 3. Describe the management of large sessile colonic polyps (LSCP) in the BCSP and explore factors which influence the choice of treatment modality (surgical or endoscopic) and subsequent outcome. A national study of LSCP management was undertaken. Detection and Management of Colorectal Neoplasia in the NHS Bowel Cancer Screening Programme Results ADR correlated positively with other performance indicators including withdrawal time and caecal intubation rate. The yield of advanced colonic neoplasia (ACN) at surveillance colonoscopy was 6.6%. The presence of right sided or villous lesions at baseline may predict the presence of ACN at surveillance. 121/557 LSCP (21.7%) were managed surgically, 436/557 (78.3%) were managed endoscopically. Increasing size was associated with failure of endoscopic therapy and presence of cancer in the resection specimen. Conclusion ADR is a satisfactory indicator of colonoscopic performance. Measures of the total number of adenomas detected are likely to be more discriminatory indicators of performance. The optimal mean withdrawal time for adenoma detection was 10 minutes. Longer mean withdrawal times were not associated with increasing adenoma detection. 12 month surveillance for high risk individuals is justified by the yield of advanced lesions. Larger or right sided LSCP were more likely to be managed surgically. Safe and effective management of LSCP can be delivered by a national screening programme.