P53 MUTATIONS IN GASTRIC CANCERS FROM TAIWAN

Mutations of the p53 gene were investigated in 80 surgical specimens o f primary gastric cancer by polymerase chain reaction single-strand co nformation polymorphism (PCR-SSCP) analysis. Mutations were detected i n 18 tumors (22.5%) and localized to exons 5, 7 and 8. Mutations did n ot follow a random distribution among different subtypes, but instead clustered in the group of papillary adenocarcinomas, in which 7/12 (58 .3%) cases were mutated. Positivity for p53 mutation was significantly higher in intestinal-type (37.5%) than in diffuse-type carcinomas (12 .5%). These results suggest that gene alterations of p53 are not rare and may participate in the carcinogenesis of intestinal-type carcinoma s of the stomach. Twenty of 21 p53 mutations were represented by singl e nucleotide changes, mostly missense mutations (19 events) and one no nsense mutation. Transversional mutations constitute the majority of p 53 mutations (65%) and only 20% of mutations show G:C to A:T transitio ns. It is possible that the etiologies of gastric cancer in different geographical areas are different.