Prevalence and prognosis of microsatellite instability in oesogastric adenocarcinoma, NORDICAP 16-01 - 16/06/21
for NORDICAP
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Highlights |
• | Microsatellite instability prevalence is 12.4%. |
• | Patients in MSI group have a lower cumulative incidence of recurrence after surgery. |
• | There is a 100% concordance between molecular analysis and IHC to determine MSI. |
• | Tumors with MSI phenotype has no BRAF V600E mutation. |
Abstract |
Background |
The prevalence and prognosis association of microsatellite instability (MSI) in oesogastric junction and gastric adenocarcinoma (OGC) have been reported with conflicting results.
Methods |
Patients with OGC from 2010 to 2015 were enrolled in this retrospective multicenter study. MSI was determined by genotyping. MLH1 promoter methylation and BRAF V600E mutation were screened in the MSI tumors.
Results |
Among 315 tumors analyzed, 39 (12.4%) were of the MSI phenotype. Compared to MSS tumors, MSI tumors were more frequent in patients >70 years (17% vs 9%, p=0.048) and in gastric antral primary (20% versus 5% in junction tumor and 12% in fundus tumor. Among 29 MSI tumors analyzed, 28 had a loss of MLH1 protein expression and 27 had MLH1 promotor hypermethylation. None had a BRAF V600E mutation. The 4-year cumulative incidence of recurrence for patients with resected tumor was significantly lower in dMMR tumors versus pMMR tumors (17% versus 47%, p=0.01). For the patients with unresectable tumor the median overall survival was 11 months in MSS group and 14 months in MSI group (p=0.24).
Conclusion |
MSI prevalence in OGC was 12.4%, associated with antral localization and advanced age. Patients with MSI tumors had a lower cumulative incidence of recurrence after surgery. MSI phenotype was mainly associated with loss of MLH1 protein expression, MLH1 promotor hypermethylation and had no BRAF V600E mutation.
Le texte complet de cet article est disponible en PDF.Keywords : Gastric cancer, Mismatch repair deficiency, Microsatellite instability
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Vol 45 - N° 4
Article 101691- juillet 2021 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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