title: Lynch syndrome screening in newly diagnosed colorectal cancer in general pathology practice: from the revised Bethesda guidelines to a universal approach.
abstract: OBJECTIVE
  Lynch syndrome (LS) is the most common hereditary form of colorectal cancer (CRC). The revised 2004 Bethesda guidelines were developed to identify potential LS patients. This study aimed to retrospectively evaluate utilization and adequacy of the guidelines in general pathology practice and to determine if a universal LS screening approach increased the potential LS detection rate in newly diagnosed CRCs.
  
  
  METHODS
  Included were 445 primary CRCs surgically resected from November 2006 to March 2009, when reflex microsatellite instability (MSI) testing was based on histomorphology and age as well as 145 CRCs resected from July 2009 to July 2010 when a universal LS testing paradigm was used. Reflex MSI testing rates and MSI testing results were determined.
  
  
  RESULTS
  The overall LS screening rate from November 2006 to March 2009 was 34.8%, and the extrapolated microsatellite instability-high (MSI-H) rate was 8.5% (38/445). Strict adherence to the revised Bethesda guidelines, that is, without testing CRC diagnosed in patients ‡60 years, would have missed 26 (68.4%) MSI-H CRCs. The overall LS screening rate from July 2009 to July 2010 was 76.3% and the MSI-H rate was 20.6% (30/145). Compared with the MSI tested group, the untested group had more CRCs removed by local excision (22.2% vs. 4.8%, p = 0.00035).
  
  
  CONCLUSIONS
  The revised Bethesda guidelines are inadequate for LS screening when personal and family cancer history is not available to the pathologist, a universal screening paradigm greatly increased the rate of MSI testing and MSI-H CRC detection and CRCs less likely to be screened for LS were those diagnosed in locally excised specimens.
authors: Department of Anatomic Pathology , Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors: Jane
authors: J
authors: Morrison
authors: Mary
authors: M
authors: Bronner
authors: Brandie H
authors: BH
authors: Leach
authors: Erinn
authors: E
authors: Downs-Kelly
authors: John R
authors: JR
authors: Goldblum
authors: Xiuli
authors: X
authors: Liu
mesh_terms: D000367:Age Factors; D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000235:genetics* / Q000473:pathology; D005260:Female; D005820:Genetic Testing / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D053842:Microsatellite Instability; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D012189:Retrospective Studies