title: Population-Based Lynch Syndrome Screening by Microsatellite Instability in Patients ≤50: Prevalence, Testing Determinants, and Result Availability Prior to Colon Surgery.
abstract: OBJECTIVE
  As there are no US population-based studies examining Lynch syndrome (LS) screening frequency by microsatellite instability (MSI) and immunohistochemistry (IHC), we seek to quantitate statewide rates in patients aged ≤50 years using data from a Centers for Disease Control and Prevention-funded Comparative Effectiveness Research (CER) project and identify factors associated with testing. Screening rates in this young, high-risk population may provide a best-case scenario as older patients, potentially deemed lower risk, may undergo testing less frequently. We also seek to determine how frequently MSI/IHC results are available preoperatively, as this may assist with decisions regarding colonic resection extent.
  
  
  METHODS
  Data from all Louisiana colorectal cancer (CRC) patients aged ≤50 years diagnosed in 2011 were obtained from the Louisiana Tumor Registry CER project. Registry researchers and physicians analyzed data, including pathology and MSI/IHC.
  
  
  RESULTS
  Of the 2,427 statewide all-age CRC patients, there were 274 patients aged ≤50 years, representing health care at 61 distinct facilities. MSI and/or IHC were performed in 23.0% of patients. Testing-associated factors included CRC family history (P<0.0045), urban location (P<0.0370), and care at comprehensive cancer centers (P<0.0020) but not synchronous/metachronous CRC or MSI-like histology. Public hospital screening was disproportionately low (P<0.0217). Of those tested, MSI and/or IHC was abnormal in 21.7%. Of those with abnormal IHC, staining patterns were consistent with LS in 87.5%. MSI/IHC results were available preoperatively in 16.9% of cases.
  
  
  CONCLUSIONS
  Despite frequently abnormal MSI/IHC results, LS screening in young, high-risk patients is low. Provider education and disparities in access to specialized services, particularly in underserved populations, are possible contributors. MSI/IHC results are infrequently available preoperatively.
authors.affiliation: Division of Gastroenterology, Tulane University School of Medicine, New Orleans, Louisiana, USA.
authors.forename: Jordan J
authors.initials: JJ
authors.lastname: Karlitz
authors.affiliation: Louisiana Tumor Registry, Epidemiology Program, LSU Health Sciences Center School of Public Health, New Orleans, Louisiana, USA.
authors.forename: Mei-Chin
authors.initials: MC
authors.lastname: Hsieh
authors.affiliation: Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Division of Gastroenterology, Tulane University School of Medicine, New Orleans, Louisiana, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Blanton
authors.affiliation: Louisiana Tumor Registry, LSU Health Sciences Center School of Public Health, New Orleans, Louisiana, USA.
authors.forename: Beth
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: Cancer Diagnosis Program-National Cancer Institute (NCI), Division of Cancer Treatment and Diagnosis (DCTD), National Institute of Health (NIH), Rockville, Maryland, USA.
authors.forename: J Milburn
authors.initials: JM
authors.lastname: Jessup
authors.affiliation: Louisiana Tumor Registry, Epidemiology Program, LSU Health Sciences Center School of Public Health, New Orleans, Louisiana, USA.
authors.forename: Xiao-Cheng
authors.initials: XC
authors.lastname: Wu
authors.affiliation: Louisiana Tumor Registry, Epidemiology Program, LSU Health Sciences Center School of Public Health, New Orleans, Louisiana, USA.
authors.forename: Vivien W
authors.initials: VW
authors.lastname: Chen
mesh_terms: D000328:Adult; D000367:Age Factors; D003082:Colectomy; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics* / Q000517:prevention & control / Q000601:surgery; D015986:Confounding Factors, Epidemiologic; D055088:Early Detection of Cancer / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D005820:Genetic Testing; D006801:Humans; D007150:Immunohistochemistry; D008145:Louisiana / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D053842:Microsatellite Instability; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000235:genetics; D016609:Neoplasms, Second Primary / Q000235:genetics; D057234:Preoperative Period; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data