Journal Article

Effect of screening sigmoidoscopy and screening colonoscopy on colorectal cancer incidence and mortality: systematic review and meta-analysis of randomised controlled trials and observational studies

Stock, Christian, Hoffmeister, Michael, Brenner, Hermann

2014

Overview

Objectives To review, summarise, and compare the evidence for effectiveness of screening sigmoidoscopy and screening colonoscopy in the prevention of colorectal cancer occurrence and deaths.Design Systematic review and meta-analysis of randomised controlled trials and observational studies.Data sources PubMed, Embase, and Web of Science. Two investigators independently extracted characteristics and results of identified studies and performed standardised quality ratings.Eligibility criteria Randomised controlled trials and observational studies in English on the impact of screening sigmoidoscopy and screening colonoscopy on colorectal cancer incidence and mortality in the general population at average risk.Results For screening sigmoidoscopy, four randomised controlled trials and 10 observational studies were identified that consistently found a major reduction in distal but not proximal colorectal cancer incidence and mortality. Summary estimates of reduction in distal colorectal cancer incidence and mortality were 31% (95% confidence intervals 26% to 37%) and 46% (33% to 57%) in intention to screen analysis, 42% (29% to 53%) and 61% (27% to 79%) in per protocol analysis of randomised controlled trials, and 64% (50% to 74%) and 66% (38% to 81%) in observational studies. For screening colonoscopy, evidence was restricted to six observational studies, the results of which suggest tentatively an even stronger reduction in distal colorectal cancer incidence and mortality, along with a significant reduction in mortality from cancer of the proximal colon. Indirect comparisons of results of observational studies on screening sigmoidoscopy and colonoscopy suggest a 40% to 60% lower risk of incident colorectal cancer and death from colorectal cancer after screening colonoscopy even though this incremental risk reduction was statistically significant for deaths from cancer of the proximal colon only.Conclusions Compelling and consistent evidence from randomised controlled trials and observational studies suggests that screening sigmoidoscopy and screening colonoscopy prevent most deaths from distal colorectal cancer. Observational studies suggest that colonoscopy compared with flexible sigmoidoscopy decreases mortality from cancer of the proximal colon. This added value should be examined in further research and weighed against the higher costs, discomfort, complication rates, capacities needed, and possible differences in compliance.

• Publisher: British Medical Journal Publishing Group,BMJ Publishing Group LTD,BMJ Publishing Group Ltd
• Subject: Canada - epidemiology / Colon / Colon cancer / Colonic Neoplasms - diagnosis / Colonic Neoplasms - mortality / Colonoscopy / Colonoscopy - mortality / Colorectal cancer / Colorectal carcinoma / Confidence intervals / Early Detection of Cancer - mortality / Endoscopy / Europe - epidemiology / Gastroenterology / Health risk assessment / Humans / Incidence / Medical screening / Meta-analysis / Mortality / Motivation / Observational Studies as Topic / Population / Quality / Randomized Controlled Trials as Topic / Rectal Neoplasms - diagnosis / Rectal Neoplasms - mortality / Reviews / Risk Reduction Behavior / Sigmoidoscopy / Sigmoidoscopy - mortality / Statistical analysis / Studies / Trends / United States - epidemiology