K-ras mutations in gastric stump carcinomas and in carcinomas from the non-operated stomach

BACKGROUND/AIMS: Partial gastrectomy is a well-established pre-malignant co ndition. It is postulated that in the gastric stump an accelerated neoplast ic process takes place, similar to that of (intestinal type) adenocarcinoma from the non-operated stomach. K-ras codon 12 mutation is one of the most frequent oncogenic alterations in human solid neoplasms. It is rare in conv entional gastric carcinoma and has not been studied in gastric stump carcin oma. The aim of this study was to compare the prevalence of K-ras codon 12 point mutations in gastric stump carcinomas with those in conventional carc inomas from the non-operated stomach. METHODOLOGY: Twenty-four gastric stump carcinomas were compared with 26 con ventional gastric carcinomas. Stage, histology, and demographics were compa rable in both groups. Mutations in codon 12 of the K-ras gene were examined with a polymerase chain reaction (PCR)-based method and subsequent dot blo t hybridization with mutation-specific probes. The results of Helicobacter pylori infection, Epstein-Barr virus infection and p53 immunohistochemistry were partially known from a previous study. RESULTS: In one of the gastric stump carcinomas as well as in one of the co nventional gastric carcinomas a K-ras codon 12 point mutation was found, p5 3 Immunohistochemistry results were comparable in both groups. Interestingl y, Helicobacter pylori infection rate and Epstein-Barr virus in situ hybrid ization for EBER1, as previously studied, appeared were significantly diffe rent in the two groups. CONCLUSIONS: K-ras codon 12 point mutations are rare in both gastric stump carcinomas and conventional gastric carcinomas. This supports the postulate d hypothesis that the pathways of carcinogenesis in both gastric stump carc inoma and conventional gastric carcinoma share common features. However, th ese groups differ in infection rate of Helicobacter pylori and of Epstein-B arr virus, which suggests that some neoplastic stimuli differ as well.