Background The RET gene point mutation is the main molecular alteration involved in medullary thyroid carcinoma (MTC) tumorigenesis. Previous studies in Vietnam mainly consisted of case reports, with limited data on larger sample sizes. In this study, we investigated RET gene mutations in exons 10, 11, and 16 and analyzed clinicopathological features of a series of Vietnamese MTC patients. Methods: We collected 33 tissue samples from patients with MTC and analyzed RET mutations using the Sanger sequencing method. The relationship between hotspot RET mutations (exons 10, 11, 16) and clinicopathological features were investigated. Results: Among the 33 analyzed cases, 17 tumors (52%) harbored RET mutations in exon 10, 11, or 16. A total of 10 distinct genetic alterations were identified, including eight missense mutations and two short indels. Of these, seven were classified as pathogenic mutations based on previous publications, with p.M918T being the most frequent (4 cases), followed by p.C634R (3 cases) and p.C618R (3 cases). Mutations were significantly associated with specific histological patterns, such as the nested/insular pattern (p=.026), giant cells (p=.007), nuclear pleomorphism (p=.018), stippled chromatin (p=.044), and amyloid deposits (p=.024). No mutations were found in germline analyses, suggesting these were somatic alterations. Conclusions: Our results provided the first comprehensive analysis of RET mutations in Vietnamese MTC patients. The most frequent mutation was p.M918T, followed by p.C634R and p.C618R. Mutations in these three exons were linked to specific histopathological features. Information on mutational profiles of patients with MTC will further aid in the development of targeted therapeutics to ensure effective disease management.
Background Human epidermal growth factor receptor 2 (HER2) is related to the pathogenesis and poor outcome of numerous types of carcinomas, including gastric carcinoma. Gastric cancer patients with HER2 positivity have become potential candidates for targeted therapy with trastuzumab.
Methods We investigated 208 gastric cancer specimens using immunohistochemistry (IHC), fluorescence in situ hybridization and dual in situ hybridization (ISH). We also investigated the concordance between IHC and ISH. The correlation between HER2 status and various clinicopathological findings was also investigated.
Results In total, 15.9% (33/208) and 24.5% (51/208) of gastric cancers showed HER2 gene amplification and protein overexpression, respectively. A high level of concordance between ISH and IHC analyses (91.3%, κ = 0.76) was found. A significant correlation between HER2 status and intestinal-type (p < .05) and differentiated carcinomas (p < .05) was also noted. The HER2 heterogeneity was high in gastric cancers; we found 68.8% phenotypic heterogeneity and 57.6% genotypic heterogeneity. Heterogeneity in HER2 protein expression and gene amplification showed a close association with diffuse histologic type and IHC 2+.
Conclusions HER2 protein overexpression and gene amplification were detected in 24.5% and 15.9% of gastric cancer specimens, respectively. Intestinal-type showed a higher level of HER2 protein overexpression and gene amplification than diffuse type. HER2 status also showed a significant relationship with well- and moderately-differentiated carcinomas. The ratio of phenotypic and genotypic heterogeneity of HER2 was high in gastric carcinomas and was associated with HER2 IHC 2+ and diffuse histologic type.
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