Abstract
Abstract
Background:
Colorectal cancer (CRC) is a rising health challenge in Uganda. The mismatch repair (MMR) system, particularly MSH2 and MLH1, plays a critical role in maintaining genomic stability; defects contribute to CRC development. Immunohistochemistry (IHC) is a cost-effective method for detecting MMR protein expression in CRC tissues and aids diagnosis and treatment.
Study design:
The study was a retrospective cross-sectional design
Objectives
: To determine the immunohistochemical expression of MSH2 and MLH1 in archived CRC tissue blocks at the Uganda Cancer Institute (UCI) and to assess their correlation with tumor histological grades.
Methods:
A retrospective analysis of 41 CRC tissue blocks collected from August 2017 to June 2023 was conducted using IHC. Histologically confirmed tissue sections were immunostained with MLH1 and MSH2 antibodies. Spearman’s correlation assessed relationships between protein expression and tumor differentiation.
Results
: MSH2 was expressed in 95% of tissue blocks and MLH1 in 92.7%. Loss of MSH2 and MLH1 occurred in 5% and 7.3% of cases, respectively. Most tumors were well differentiated (58.5%), followed by moderately (24.4%) and poorly differentiated (17.1%). There was no significant correlation between MSH2 expression and CRC grades (p = 0.151). MLH1 expression showed a positive correlation with poorly differentiated tumors (rho = 0.414, p = 0.007).
Conclusion:
MSH2 and MLH1 are largely retained in CRC cases at UCI, suggesting MMR deficiencies are not predominant. Further studies including molecular analysis of MMR mutations and microsatellite instability (MSI) are recommended to clarify MMR defects in Ugandan CRC.