Aim: Colorectal cancer (CRC) is diagnosed in approximately 45 000 people annually in the UK, and it is estimated that Lynch syndrome (LS) accounts for 3.1% of these cases. In February 2017, National Institute for Health and Care Excellence (NICE guideline DG27 recommended universal testing of new cases of CRC for mismatch repair (MMR) status. The aim of this study was to implement universal testing for LS in CRC patients in a secondary care setting.
Method: We prospectively collected data on consecutive newly diagnosed CRC patients at our centre from November 2016 to August 2018, including evidence of MMR status determined by immunohistochemistry. We recorded clinicopathological data including age at diagnosis, stage, tumour site, reported histological findings and MMR tumour status. Statistical analysis was performed using the chi-square test and the two-tailed t-test for binary and continuous variables, respectively.
Results: A cohort of 203 consecutive patients were diagnosed with CRC during this period. Universal MMR testing was performed for the 198 CRC patients in whom a diagnosis of adenocarcinoma was confirmed, with colonoscopic biopsy used as the source material in 68.6% of cases. Twenty-three CRCs (11.6%) were MMR deficient (dMMR). Most dMMR CRCs (21/23) were early stage tumours (Dukes A or B, P = 0.002). In 39 Dukes B CRCs in patients under 70 years of age, the result of MMR testing influenced decision-making about personalized treatment with 5-fluorouracil based chemotherapy.
Conclusion: Our results demonstrate that universal testing of all new cases of CRC for features suggestive of LS is feasible and effective in the UK. Our data also indicate the importance of genetic testing and personalized oncological care.
Keywords: Colorectal Cancer; HNPCC; Lynch syndrome; colonoscopy; genetic testing.
Colorectal Disease © 2019 The Association of Coloproctology of Great Britain and Ireland.