Gut doi:10.1136/gutjnl-2012-303796
  • Colon cancer
  • Original article

Colorectal cancers soon after colonoscopy: a pooled multicohort analysis

  1. María Elena Martínez8,9
  1. 1Department of Veterans Affairs Medical Center, White River Junction, VT and Dartmouth Medical School & The Dartmouth Institute, Hanover, New Hampshire, USA
  2. 2Department of Veterans Affairs Medical Center, Portland, Oregon, USA
  3. 3Memorial Sloan-Kettering Cancer Center, New York, New York, USA
  4. 4Department of Veterans Affairs Medical Center, University of Colorado Denver and University of Colorado Cancer Center, Denver, Colorado, USA
  5. 5University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
  6. 6Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
  7. 7Division of Environmental Health Sciences, University of Minnesota School of Public Health, Minneapolis, Minnesota, USA
  8. 8Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
  9. 9Mel and Enid Zuckerman Arizona College of Public Health, University of Arizona, Tucson, Arizona, USA
  10. 10Department of Medicine, University of Arizona, Tucson, Arizona, USA
  11. 11Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
  12. Deceased
  1. Correspondence to Dr Douglas J Robertson, VA Medical Center, 215 N Main Street/Section of Gastroenterology (111E), White River Junction, VT 05009, USA; douglas.robertson{at}
  • Received 21 September 2012
  • Revised 14 May 2013
  • Accepted 24 May 2013
  • Published Online First 21 June 2013


Objective Some individuals are diagnosed with colorectal cancer (CRC) despite recent colonoscopy. We examined individuals under colonoscopic surveillance for colonic adenomas to assess possible reasons for diagnosing cancer after a recent colonoscopy with complete removal of any identified polyps.

Design Primary data were pooled from eight large (>800 patients) North American studies in which participants with adenoma(s) had a baseline colonoscopy (with intent to remove all visualised lesions) and were followed with subsequent colonoscopy. We used an algorithm based on the time from previous colonoscopy and the presence, size and histology of adenomas detected at prior exam to assign interval cancers as likely being new, missed, incompletely resected (while previously an adenoma) or due to failed biopsy detection.

Results 9167 participants (mean age 62) were included in the analyses, with a median follow-up of 47.2 months. Invasive cancer was diagnosed in 58 patients (0.6%) during follow-up (1.71 per 1000 person-years follow-up). Most cancers (78%) were early stage (I or II); however, 9 (16%) resulted in death from CRC. We classified 30 cancers (52%) as probable missed lesions, 11 (19%) as possibly related to incomplete resection of an earlier, non-invasive lesion and 14 (24%) as probable new lesions. The cancer diagnosis may have been delayed in three cases (5%) because of failed biopsy detection.

Conclusions Despite recent colonoscopy with intent to remove all neoplasia, CRC will occasionally be diagnosed. These cancers primarily seem to represent lesions that were missed or incompletely removed at the prior colonoscopy and might be avoided by increased emphasis on identifying and completely removing all neoplastic lesions at colonoscopy.

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