# Clinicopathological Implications of Mismatch Repair Status in Endometrioid Endometrial Cancer in Duhok City

## TL;DR

This study examines the role of DNA mismatch repair in endometrial cancer in Duhok City, finding that many patients had a defective repair system linked to older age.

## Contribution

The study provides local data on MMR status in endometrioid endometrial cancer and its clinicopathological correlations in Duhok City.

## Key findings

- 44% of patients showed loss in nuclear expression of MMR proteins.
- MLH1 and PMS2 protein loss was the most common, at 18%.
- Most patients with d-MMR were over 50 years old.

## Abstract

Background: DNA mismatch repair (MMR) is a specialized system that corrects errors in DNA replication, namely, base substitution mismatches and minor insertion-deletion mismatches. The deficient mismatch repair (d-MMR) protein plays a vital role in predicting the prognosis of endometrioid carcinoma. The study aimed to determine the prevalence of MMR errors in endometrial cancer (EC) and their correlation with clinicopathological features.

Methods: We examined the immunohistochemistry presence of four MMR proteins in 50 samples of EC tissues that were preserved in formalin and embedded in paraffin. The proteins identified were MutL homolog 1 (MLH1), post-meiotic segregation increased 2 (PMS2), MutS homolog 2 (MSH2), and MutS homolog 6 (MSH6). The study examined several clinicopathological characteristics and conducted MMR phenotyping.

Results: The findings revealed that among the 50 cases of EC, 40% of patients had grade I disease and 78% had stage I malignancy. Furthermore, among the 50 individuals evaluated, 56% exhibited competence in MMR, whereas 44% displayed loss in nuclear expression of MMR. The rate of MLH1 and PMS2 protein loss was recorded as the greatest, at 18%, while the loss of MSH2 and MSH6 was documented at 6%. Within the same range, the majority of patients with d-MMR were above the age of 50 years.

Conclusion: The majority of the recruited EC patients in this study showed advanced age and a high percentage of d-MMR status.