Compliance of a Tertiary Centre With Molecular Testing Strategies for Lynch Syndrome in Colorectal Cancer

Introduction Lynch syndrome is one of the most common hereditary cancers associated with germline alterations of DNA mismatch repair genes. Recent advances have shed light on its molecular pathogenesis, leading to the development of various testing strategies. The aim of this study is to evaluate whether all colorectal adenocarcinomas undergo immunohistochemistry (IHC) and microsatellite instability (MSI) testing to identify potential Lynch syndrome patients. Methods This study evaluated the compliance of MSI and IHC testing for Lynch syndrome in a tertiary cancer research centre. All patients undergoing colorectal cancer resection between April 2022 and December 2022 were identified from a prospectively maintained register. The histology, MSI, and IHC testing reports for these patients were recorded to check if they were done and reported. Only patients with colorectal adenocarcinoma were included in this study. Results A total of 314 patients had colorectal cancer resections. A total of 301 were included in the study, with a median age of 65 years (IQR = 35-95). Thirteen (4.14%) patients did not have MSI and IHC testing reported on the system. Of these, eight (61.53%) did not have an MSI/IHC testing request, four (30.76%) did not have sufficient specimens to be sent for further testing, one (7.69%) had MSI and IHC testing but the final report was yet to be authorized. Out of the eight who did not have the testing done, three had early polyp cancer and one had a goblet cell adenocarcinoma. Conclusion According to the data, our hospital has a 97.45% compliance with current guidelines, not considering the insufficient sample for testing and the authorization of the final report. A more comprehensive proforma may be needed to provide a feedback loop for further MSI and IHC testing when entering data into the system. Further auditing is required to check the effectiveness of the proforma in achieving complete compliance.