Hereditary Colorectal Cancer in Brunei Darussalam

Abstract

Introduction: Hereditary colorectal cancers (CRC) are associated with early age of disease onset and high risks of developing other cancers. In this study, we estimate the prevalence of hereditary CRC over a 6-year period, and report the socio-demographics and clinical profile of patients in Brunei Darussalam. Methods: A retrospective study of data from 146 patients diagnosed with CRC from January 2017 to December 2022 was obtained from The Brunei Cancer Centre. Suspected or confirmed hereditary CRC patients were flagged from the 146 cases based on microsatellite instability (MSI) assay testing, immunohistochemistry (IHC) four-panel staining on mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2, and BRAFV600E test results. Results: Among the 146 patients with CRC, 41.7% (n=61) patients underwent MSI testing where 7.5% (n=11) reported high instability in their microsatellite assay (MSI-H), of which 2 were associated with Lynch syndrome. Among the 11 patients with “suspected” or “confirmed” hereditary colorectal cancer, majority presented with abdominal pain prior to diagnosis (81.8%; n=9), Stage 2 cancer (36.4%; n=4), moderately differentiated tumour (72.7%; n=8), tumour located in caecum (36.4%; n=4) and all patients had surgery as first-line management, with more than half receiving chemotherapy (54.5%; n=6). Conclusion: 7.5% of patients of CRC cases seen at a tertiary cancer centre over a 6-year period was found to have “suspected” or “confirmed” hereditary CRC. The lack of genetic testing performed in local settings may indicate that the actual prevalence may be higher.