Population-Based Lynch Syndrome Screening by Microsatellite Instability in Patients ≤50: Prevalence, Testing Determinants, and Result Availability Prior to Colon Surgery

Am J Gastroenterol. 2015 Jul;110(7):948-55. doi: 10.1038/ajg.2014.417. Epub 2015 Jan 20.

Abstract

Objectives: 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.

Publication types

  • Multicenter Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Colectomy*
  • Colorectal Neoplasms, Hereditary Nonpolyposis / diagnosis*
  • Colorectal Neoplasms, Hereditary Nonpolyposis / epidemiology
  • Colorectal Neoplasms, Hereditary Nonpolyposis / genetics*
  • Colorectal Neoplasms, Hereditary Nonpolyposis / prevention & control
  • Colorectal Neoplasms, Hereditary Nonpolyposis / surgery
  • Confounding Factors, Epidemiologic
  • Early Detection of Cancer* / methods
  • Early Detection of Cancer* / standards
  • Early Detection of Cancer* / statistics & numerical data
  • Female
  • Genetic Testing*
  • Humans
  • Immunohistochemistry
  • Louisiana / epidemiology
  • Male
  • Mass Screening* / methods
  • Mass Screening* / standards
  • Mass Screening* / statistics & numerical data
  • Microsatellite Instability*
  • Middle Aged
  • Neoplasms, Multiple Primary / genetics
  • Neoplasms, Second Primary / genetics
  • Preoperative Period
  • Prevalence
  • Rural Population / statistics & numerical data
  • Time Factors
  • United States / epidemiology
  • Urban Population / statistics & numerical data