Prevalence of Mismatch Repair-Deficient Colorectal Adenoma/Polyp in Early-Onset, Advanced Cases: a Cross-Sectional Study Based on Iranian Hereditary Colorectal Cancer Registry

J Gastrointest Cancer. 2021 Mar;52(1):263-268. doi: 10.1007/s12029-020-00395-y.

Abstract

Background: Lynch syndrome (LS) increases the risk of many types of cancer, mainly colorectal cancer (CRC). The purpose of this study was to assess the prevalence of mismatch repair (MMR) deficiency in patients under the age of 50 with advanced adenomatous polyps, aiming at an early diagnosis of LS.

Methods: This retrospective, cross-sectional study included eligible patients with advanced adenomas diagnosed ≤ 50 years of age registered between April 2014 and February 2017 at three pathology centers in Mashhad. Pathological records were reviewed, and colon tissue specimens were analyzed by immunohistochemistry (IHC) staining to identify proteins which serve as markers for LS as they are related to loss of MMR gene (MLH1, MSH2, MSH6, and PMS2) expression.

Results: Of 862 consecutive patients, a total of 50 adenomas (54% males, 46% females of mean age 41.24 ± 6.5) met the eligibility criteria. Of the adenomas examined, 20 (40%) had a tubulovillous component, 34 (68%) had high-grade dysplasia, and 30 (60%) had were larger than 10 mm protrusions. None of the patients had loss of MMR protein expression.

Conclusion: No individual with MMR genetic disorder was identified by IHC screening of early-onset advanced colorectal adenomas. This strategy is therefore not an effective strategy for detecting MMR mutation carriers.

Keywords: Adenoma; Immunohistochemistry; Iran; Lynch syndrome; Mismatch repair; Polyp.

MeSH terms

  • Adenomatous Polyps / diagnosis
  • Adenomatous Polyps / genetics*
  • Adenomatous Polyps / pathology
  • Adult
  • Age of Onset
  • Colon / diagnostic imaging
  • Colon / pathology
  • Colonoscopy
  • Colorectal Neoplasms, Hereditary Nonpolyposis / diagnosis
  • Colorectal Neoplasms, Hereditary Nonpolyposis / epidemiology*
  • Colorectal Neoplasms, Hereditary Nonpolyposis / genetics
  • Colorectal Neoplasms, Hereditary Nonpolyposis / pathology
  • Cross-Sectional Studies
  • DNA Mismatch Repair*
  • Female
  • Heterozygote
  • Humans
  • Immunohistochemistry
  • Intestinal Mucosa / diagnostic imaging
  • Intestinal Mucosa / pathology
  • Iran / epidemiology
  • Male
  • Medical History Taking
  • Microsatellite Instability
  • Middle Aged
  • Molecular Epidemiology
  • Prevalence
  • Rectum / diagnostic imaging
  • Rectum / pathology
  • Registries / statistics & numerical data
  • Retrospective Studies