Significance of EGFRvIII Presence in Gastric Adenocarcinoma.

Background: The significance of epidermal growth factor receptor (EGFR) gene variants, particularly the variant known as EGFRvIII, which arises from the deletion of exons 2-8, has been extensively studied in various human carcinomas. In contrast, studies into the role of EGFRvIII in gastric cancer remain limited. The current study aims to evaluate the expression levels of EGFRvIII in patients suffering from gastric adenocarcinoma. Material and methods: In this descriptive cross-sectional study, 21 patients with gastric adenocarcinoma who referred to the university-based referral hospital, Rasoul-Akram, in Tehran, Iran, during 2018-2019, were included. The patients' characteristics including demographic features, medical archives, type and location of tumor mass, and histopathological type were recorded. In order to evaluate the expression of EGFRvIII variant, RT-PCR and sequencing techniques were used. Results: In patients with gastric adenocarcinoma, 14 cases (66.7%) were males and seven cases (33.3%) were females, and the average age of the patients was 66.62 ± 10.79 years, ranging from 45 to 89 years. In terms of the histopathological type, six cases (28.6%) were moderately differentiated (MD), four cases (19.0%) were poorly differentiated (PD), five cases (23.8%) were SIG adenocarcinoma, and six cases (28.6%) were well differentiated (WD). A total of 18 samples (85.7%) were obtained from the biopsy, while three cases (14.3%) were derived from total gastrectomy and necrosis was seen in eight cases (38.1%). Two out of 21 cases (9.5%) were EGFRvIII positive in both RT-PCR and sequencing test. The first case was an 86-year-old woman with a signet-ring cell (SIG) adenocarcinoma tumor subtype with tissue from the antrum and without necrosis. The second case was a 67-year-old man with a tumor subtype of SIG adenocarcinoma with necrotic tissue sample from the gastric cavity. The location of the mutation, two genes on ex1 and ex8, which were connected to each other, was detected in samples of both cases. Conclusion: Our findings showed detection of EGFRvIII in 9.5% of gastric adenocarcinoma cases. Although the sample size presents a limitation, the increase in expression of this variant appears to be independent of the patients' gender and age. Notably, the association of this variant with the signet-ring cell adenocarcinoma subtype is a significant finding that warrants further investigation.