An Audit Report on Mismatch Repair Deficiency Testing in Patients With Colorectal Cancer and Non-adherence to Testing Guidelines

Abstract

Background:
Mismatch repair (MMR) deficiency testing plays an important role in the management of colorectal cancer (CRC), particularly for identifying Lynch syndrome and guiding treatment decisions. Despite clear recommendations for universal testing, its use in routine practice remains inconsistent.

Objective:
To assess the utilization of MMR deficiency testing in patients with colorectal cancer and to identify factors associated with nonadherence to testing guidelines.

Methods:
This hospital-based audit included 117 patients with histologically confirmed CRC presenting between September 2025 and March 2026 at a tertiary oncology center. Clinical and demographic data were collected from medical records. The primary outcome was whether MMR/MSI testing was performed. Associations between patient characteristics and testing status were analyzed using appropriate statistical tests, with significance set at p < 0.05.

Results:
MMR/MSI testing was performed in only 28.2% of patients, while 71.8% did not undergo testing. Younger and older age groups, socioeconomic status, education level, disease stage, and family history showed significant associations with testing status. The most common reason for not undergoing testing was financial constraint (38.5%), followed by lack of physician recommendation (14.5%) and non-availability of testing facilities (7.7%). A large proportion of patients presented with advanced-stage disease.

Conclusion:
MMR deficiency testing remains underutilized in CRC patients in this setting. Financial barriers, limited access, and gaps in physician practice contribute to low testing rates. Addressing these issues is essential to improve adherence to guidelines and ensure appropriate patient care.