Scripties UMCG - Rijksuniversiteit Groningen
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Universele screening naar mismatch repair deficiëntie bij colorectaal carcinoom niet zinvol

(2018) Elferink, R.L.

Introduction: Mismatch repair (MMR)-analysis using microsatellite instability (MSI)- or immunohistochemistry (IHC)- analysis is performed in patients with colorectal carcinoma (CRC) < 70 years. Based on the results, referral to a clinical genetic centre is indicated to perform additional gene analysis to identify Lynch syndrome (LS). Moreover, the results of the MMR-analysis are important for the choice in surgery and to establish the effectiveness of adjuvant chemotherapy. The aim of this study is to determine whether universal MMR-analysis is useful. Methods: This research is a partly retrospective and partly prospective observational research. Consequences of MMR-analysis were compared between two cohorts of patients with newly diagnosed CRC before and after implementation of universal MMR-analysis in Isala. Cohort 1 consisted of all CRC-patients diagnosed between 01-01-2014 and 31-12-2017 and cohort 2 consisted of patients diagnosed between 01-01-2018 and 31-08-2018. Results: In total 529 patients were included and underwent MMR-analysis, of which 68 patients (12,9%) were classified as MMR deficient (dMMR). In cohort 1 the type of surgery was adjusted as a result of the outcome of the MMR-analysis in 3 patients, compared to 2 patients in cohort 2 (p=.349). No conclusions could be drawn from the results of the adjuvant chemotherapy. Thirty-eight patients were suspect for LS and 51 patients were referred to a clinical genetic centre. In both cohorts the same percentage of patients were referred justly (66,7%, p=1.00). However, in cohort 1, 4 patients were not referred unjust, compared to no patients from cohort 2 (p=.577). Additional gene analysis resulted in the detection of 8 gene mutations, all in patients < 70 years. Conclusion: In this study we found no significant differences between the 2 cohorts regarding the consequences of MMR-analysis. Therefore, the current guideline seems to be sufficient and universal MMR-analysis is not useful.

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