International Journal of Cancer Management
Prevalence and Immunohistochemical Patterns of Mismatch Repair Deficiency in Colorectal Adenocarcinoma: A Retrospective Cross-Sectional Study from Northwestern Iran
By Babak Nejati, Amir Vahedi, Amirhossein Tizhoosh and 1 others.
Abstract
Background
Deficient mismatch repair in colorectal adenocarcinoma is a clinically relevant biomarker for Lynch syndrome screening, prognostic assessment, and therapeutic stratification. However, regional data on the prevalence of dMMR and immunohistochemical patterns of protein loss remain limited in Iran.
Objectives
This study aimed to determine the prevalence of dMMR and to characterize mismatch repair (MMR) protein loss patterns in a colorectal cancer cohort in Northwestern Iran.
Methods
In this retrospective cross-sectional study, we analyzed consecutive colorectal cancer cases using immunohistochemistry (IHC) for MLH1, PMS2, MSH2, and MSH6. Deficient MMR was defined as the loss of nuclear expression of at least 1 MMR protein in tumor cells, with retained staining in internal control cells. We assessed the prevalence of dMMR and the distribution of MMR protein loss patterns.