AN IMMUNOHISTOCHEMICAL STUDY OF P53 PROTEIN IN THE DIFFERENT HISTOLOGICAL SUBTYPES OF GASTRIC-CARCINOMA

p53 mutations are known to occur frequently in human cancers, includin g gastric carcinomas. Previous studies of its incidence in gastric car cinomas had shown a varying incidence ranging from a low of 4% to as h igh as 57%. In this study, 42 cases of gastric carcinomas were analyze d for p53 using a commercially available mouse monoclonal antibody in routinely formalin-fixed paraffin-embedded tissue sections. These incl uded 22 intestinal-type (7 well/moderately differentiated and 15 poorl y differentiated), 16 diffuse-type and 4 mixed. Altogether, 60% of our cases stained positively for p53. Overall, well/moderately differenti ated intestinal-type carcinomas stained more frequently for p53 than p oorly differentiated intestinal-type carcinomas (p<0.075). A compariso n between the incidence in diffuse-type (69%) and intestinal type (55% ) was unremarkable. p53 staining was also present in 3 of the 4 early cases studied. The results suggest that p53 mutations play an importan t role in carcinogenesis in gastric carcinoma and further implies that p53 mutation may be an early occurrence during tumor transformation.