Résumé
P53 is a tumor suppressor gene product identified in a wide variety of tumors. It is a nuclear phosphoprotein encoded by a gene at position 13 on the short arm of chromosome 17. Studies have shown that wild type p53 has an inhibitory effect on cell proliferation and transformation. Mounting evidence indicated that p53 is involved in the pathogenesis of a large proportion of human neoplasms as a major biochemical regulator of growth control. Mutation of p53 was found in 50% of gastric cancer and 90% of esophageal cancer. This work studied the accumulation of p53 by immunohistochemistry in 20 patients with gastric carcinoma who underwent surgery in Kasr El-Aini Hospital. Expression of the p53 protein was found in 50% of all tumors. Expression of p53 was found in 62.5% of patients with tumors in the upper region, 50% of the patients with tumors in the middle region and 33.3% of patients with tumors in the low region of the stomach. Expression of p53 was slightly common in the ulcerative type than in the polypoidal type. P53 was found in 54.5% of patients with advanced tumor and positive lymph node infiltration and in 44.4% of patients with early tumor and without lymph node infiltration. There was significant relationship between p53 expression and the histological type of the tumors. Many cancer cells in the intestinal type carcinomas showed nuclear p53 expression, but only few cells in diffuse type carcinomas expressed nuclear p53. The results suggested that gene alterations of p53 are not rare in gastric carcinoma and may participate in carcinogenesis of intestinal type carcinomas of the stomach. P53 expression is at present not a predictor of the outcome of patients with gastric carcinoma and can not identify subgroups of patients who may be at a higher risk