Send to

Choose Destination
Int J Colorectal Dis. 2019 Jul;34(7):1273-1281. doi: 10.1007/s00384-019-03300-7. Epub 2019 May 31.

Screening flexible sigmoidoscopy versus colonoscopy for reduction of colorectal cancer mortality.

Author information

Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
Division of Gastroenterology, University of Washington, 356424, Seattle, WA, 98105, USA.
National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Information Management Services, Inc., Calverton, MD, USA.
Kaiser Permanente Washington Health Research Institute, Seattle, WA, USA.
Department of Epidemiology, University of Washington, Seattle, WA, USA.



Colonoscopy and flexible sigmoidoscopy are both recommended colorectal cancer (CRC) screening strategies, but their relative effectiveness is unclear. We sought to evaluate the ability of each of these two modalities to reduce CRC mortality.


We conducted a case-control study using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Cases were persons aged 70-85 years who died of CRC and were matched to up to three non-CRC controls. Receipt of endoscopy was ascertained from Medicare claims and endoscopy indication assigned using a validated algorithm. Conditional logistic regression models were developed to estimate the association between screening colonoscopy or sigmoidoscopy and CRC mortality. We conducted secondary analyses by race, sex, and endoscopist characteristics, and with varying duration of the look-back period.


In the initial analysis using all available look-back years, screening flexible sigmoidoscopy was associated with a 35% reduction in CRC mortality (OR 0.65, 95% CI 0.48, 0.89), while screening colonoscopy was associated with a 74% reduction (OR 0.26, 95% CI 0.23, 0.30). Sigmoidoscopy was not associated with any reduction in proximal CRC mortality. The association between colonoscopy and reduced CRC mortality was stronger in the distal than the proximal colon. Results were similar in analyses using a 5-year look-back period.


Screening colonoscopy was associated with greater reductions in CRC mortality than screening sigmoidoscopy, and with a greater reduction in the distal than the proximal colon. These results provide additional information on the relative benefits of screening for CRC with sigmoidoscopy and colonoscopy.


Case-control studies; Colonoscopy; Colorectal neoplasm; Mass screening; Sigmoidoscopy


Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center