Analysis of colorectal cancer occurrence during surveillance colonoscopy in the dietary Polyp Prevention Trial

Ajay Pabby, Robert E. Schoen, Joel L. Weissfeld, Randall Burt, James W. Kikendall, Peter Lance, Moshe Shike, Elaine Lanza, Arthur Schatzkin

Research output: Contribution to journalArticlepeer-review

312 Scopus citations


Background: Interval colorectal cancer (CRC) occasionally is detected in patients who have recently undergone colonoscopy. Systematic evaluation of CRC detected after colonoscopy could identify ways to improve the quality and the outcome of colonoscopy. Methods: This study examined cancer diagnoses in the course of the dietary Polyp Prevention Trial, a randomized study of a dietary intervention on recurrence of adenomatous polyps. An algorithm was developed to classify each cancer into one of 4 etiologies: (1) incomplete removal (cancer at the site of previous adenoma), (2) failed biopsy detection (cancer in an area of suspected neoplasia with negative biopsy specimens), (3) missed cancer (large, advanced stage cancer found at a short interval after colonoscopy), or (4) new cancer (small, early stage cancer after a longer time interval). Results: Of 2079 patients, 13 had cancer detected over 5810 person years of observation (PYO) (2.2 cases/1000 PYO); 7/13 or 53.8% of patients had either a potentially "avoidable" cancer or one detectable at an earlier time interval because of incomplete removal (4/13) or missed cancer (3/13). Conclusions: Interval cancer occurs despite colonoscopy. Improved quality of colonoscopy may have reduced cancer prevalence or resulted in earlier cancer detection in over 50% of prevalent cancers in the dietary Polyp Prevention Trial.

Original languageEnglish (US)
Pages (from-to)385-391
Number of pages7
JournalGastrointestinal endoscopy
Issue number3
StatePublished - Mar 2005

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Gastroenterology


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