title: Metachronous colorectal cancers result from missed lesions and non-compliance with surveillance.
abstract: BACKGROUND
  Several studies examined the rate of colorectal cancer (CRC) developed during colonoscopy surveillance after CRC resection (ie, metachronous CRC [mCRC]), yet the underlying etiology is unclear.
  
  
  OBJECTIVE
  To examine the rate and likely etiology of mCRCs.
  
  
  METHODS
  Population-based, multicenter study. Review of clinical and histopathologic records, including data of the national pathology database and The Netherlands Cancer Registry.
  
  
  METHODS
  National cancer databases reviewed at 3 hospitals in South-Limburg, The Netherlands.
  
  
  METHODS
  Total CRC population diagnosed in South-Limburg from January 2001 to December 2010.
  
  
  METHODS
  Colonoscopy.
  
  
  METHODS
  We defined an mCRC as a second primary CRC, diagnosed >6 months after the primary CRC. By using a modified algorithm to ascribe likely etiology, we classified the mCRCs into cancers caused by non-compliance with surveillance recommendations, inadequate examination, incomplete resection of precursor lesions (CRC in same segment as previous advanced adenoma), missed lesions, or newly developed cancers.
  
  
  RESULTS
  We included a total of 5157 patients with CRC, of whom 93 (1.8%) had mCRCs, which were diagnosed on an average of 81 months (range 7-356 months) after the initial CRC diagnosis. Of all mCRCs, 43.0% were attributable to non-compliance with surveillance advice, 43.0% to missed lesions, 5.4% to incompletely resected lesions, 5.4% to newly developed cancers, and 3.2% to inadequate examination. Age-adjusted and sex-adjusted logistic regression analyses showed that mCRCs were significantly smaller in size (odds ratio [OR] 0.8; 95% confidence interval [CI], 0.7-0.9) and more often poorly differentiated (OR 1.7; 95% CI, 1.0-2.8) than were solitary CRCs.
  
  
  CONCLUSIONS
  Retrospective evaluation of clinical data.
  
  
  CONCLUSIONS
  In this study, 1.8% of all patients with CRC developed mCRCs, and the vast majority were attributable to missed lesions or non-compliance with surveillance advice. Our findings underscore the importance of high-quality colonoscopy to maximize the benefit of post-CRC surveillance.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Chantal M C
authors.initials: CM
authors.lastname: le Clercq
authors.affiliation: Department of Methodology and Statistics, Maastricht University Medical Center, Maastricht, The Netherlands; CAPHRI, School for Public Health and Primary Care, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Bjorn
authors.initials: B
authors.lastname: Winkens
authors.affiliation: Department of Internal Medicine and Gastroenterology, Atrium Medical Center Heerlen, Heerlen, The Netherlands.
authors.forename: C Minke
authors.initials: CM
authors.lastname: Bakker
authors.affiliation: Department of Internal Medicine and Gastroenterology, Orbis Medical Center Sittard, Sittard, The Netherlands.
authors.forename: Eric T P
authors.initials: ET
authors.lastname: Keulen
authors.affiliation: GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands; Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Geerard L
authors.initials: GL
authors.lastname: Beets
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; NUTRIM, School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Ad A M
authors.initials: AA
authors.lastname: Masclee
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sanduleanu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D000236:Adenoma / Q000175:diagnosis* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003113:Colonoscopy / Q000592:standards; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000601:surgery; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D016609:Neoplasms, Second Primary / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D010349:Patient Compliance / Q000706:statistics & numerical data*; D011159:Population Surveillance; D012189:Retrospective Studies