Mutations of p53 gene, which is one of the tumor suppressor genes, are the most common genetic abnormalities detected in human tumors. Ki-67 antigen, a proliferation marker, is a non-histon nuclear protein which is present in all phases of the cell cycle apart from G0. In this study, p53 protein accumulation and Ki-67 labelled index in specimens of benign lesions and carcinomas of the stomach were immunohistochemically investigated by using Labelled Streptavidin-Biotin (LSAB) Peroxidase method. While there was no staining of p53 in normal mucosa and benign lesions, positive staining were detected in 23 (48%) out of carcinoma cases. Proliferative activity determined by Ki-67 was significantly higher in carcinomas than gastritis cases (p<0.001). Ki-67 positivity was also higher in p53 positive cacinomas compared to the carcinomas without p53 staining (p<0.005).

As a result, it was considered that the determination of p53 protein accumulation in immunohistochemical application might not be useful for stomach carcinoma diagnosis when used alone. It was also observed that Ki-67 labelling index in the differential diagnosis of benign and malign lesions and Ki-67 determination together with p53 assay in determination of tumors with high proliferative activity might be utilized.