GASTROINTESTINAL STROMAL TUMORS - Sarra Ben Rejeb - Bog

The molecular alterations most frequently associated with GIST are mutations in the KIT and PDGFRA genes. Many other genetic abnormalities have been described, such as amplification of C-MYC, MDM2, EGFR1 and CCND1. The objective of this study was to analyze by immunohistochemical method the prognostic value of C-MYC and EGFR overexpression in GIST. We retrospectively collected 25 cases of GIST diagnosed in our department over a period of 15 years (2008-2023). The expression of EGFR and C-MYC was carried out by immunohistochemical method. C-MYC immunostaining was categorized into low and high expression levels with a threshold of 25%. The intensity of immunostaining and the percentage of EGFR-positive cells were evaluated and grouped according to the Allred score parameters. Only cases with an EGFR TS score >4 were considered overexpressed. We included 25 cases. The average age of patients was 60 years with a male-to-female ratio of 1.5. C-MYC expression was observed in 60% of cases, with elevated levels in 33% of cases.