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Effectiveness of screening colonoscopy in reducing the risk of death from right and left colon cancer: a large community-based study
  1. Chyke A Doubeni1,
  2. Douglas A Corley2,
  3. Virginia P Quinn3,
  4. Christopher D Jensen2,
  5. Ann G Zauber4,
  6. Michael Goodman5,
  7. Jill R Johnson1,
  8. Shivan J Mehta6,
  9. Tracy A Becerra3,
  10. Wei K Zhao2,
  11. Joanne Schottinger3,
  12. V Paul Doria-Rose7,
  13. Theodore R Levin2,
  14. Noel S Weiss8,
  15. Robert H Fletcher9
  1. 1 Department of Family Medicine and Community Health, The Abramson Cancer Center, Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
  2. 2 Division of Research, Kaiser Permanente Northern California, Oakland, California, USA
  3. 3 Department of Research & Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA
  4. 4 Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
  5. 5 Department of Epidemiology, Emory University, Atlanta, Georgia, USA
  6. 6 Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
  7. 7 Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
  8. 8 Department of Epidemiology, University of Washington, Seattle, Washington, USA
  9. 9 Department of Population Medicine, Harvard Medical School, Boston, Massachusetts, USA
  1. Correspondence to Professor Chyke A Doubeni, Department of Family Medicine and Community Health, Perelman School of Medicine, University of Pennsylvania, Gates 2, 3400 Spruce Street, Philadelphia PA 19104, USA; Chyke.Doubeni{at}


Objective Screening colonoscopy's effectiveness in reducing colorectal cancer mortality risk in community populations is unclear, particularly for right-colon cancers, leading to recommendations against its use for screening in some countries. This study aimed to determine whether, among average-risk people, receipt of screening colonoscopy reduces the risk of dying from both right-colon and left-colon/rectal cancers.

Design We conducted a nested case–control study with incidence-density matching in screening-eligible Kaiser Permanente members. Patients who were 55–90 years old on their colorectal cancer death date during 2006–2012 were matched on diagnosis (reference) date to controls on age, sex, health plan enrolment duration and geographical region. We excluded patients at increased colorectal cancer risk, or with prior colorectal cancer diagnosis or colectomy. The association between screening colonoscopy receipt in the 10-year period before the reference date and colorectal cancer death risk was evaluated while accounting for other screening exposures.

Results We analysed 1747 patients who died from colorectal cancer and 3460 colorectal cancer-free controls. Compared with no endoscopic screening, receipt of a screening colonoscopy was associated with a 67% reduction in the risk of death from any colorectal cancer (adjusted OR (aOR)=0.33, 95% CI 0.21 to 0.52). By cancer location, screening colonoscopy was associated with a 65% reduction in risk of death for right-colon cancers (aOR=0.35, CI 0.18 to 0.65) and a 75% reduction for left-colon/rectal cancers (aOR=0.25, CI 0.12 to 0.53).

Conclusions Screening colonoscopy was associated with a substantial and comparably decreased mortality risk for both right-sided and left-sided cancers within a large community-based population.


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  • Twitter Follow Shivan Mehta at @shivan_mehta

  • Contributors CAD, DAC, VPQ, CDJ, AGZ, MG, TAB, JS, VPD-R, TRL, NSW and RHF conceived of the study and participated in its design and coordination. CAD conducted the data analysis, interpreted the findings and drafted the original manuscript. DAC, VPQ, AGZ, JRJ, SJM, NSW and RHF contributed to interpretation of the findings and writing of the manuscript. WKZ participated in data collection and cleaning. All authors read and approved the final manuscript.

  • Funding This study was supported by an award (number U01CA151736) from the United States National Cancer Institute of the National Institutes of Health. The views expressed here are those of the authors only and do not represent any official position of the National Cancer Institute or National Institutes of Health.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Additional summary tables and sensitivity analyses are available upon request from the corresponding author.