The immunohistochemical expression of the p53-protein in gastric carcinomas. Correlation with clinicopathological factors and survival of patients.

BACKGROUND: P53-tumor suppressor gene has an essential role in controlling cell cycle and initiating carcinogenesis. In the case of gastric cancer, the role of p53-protein accumulation as prognostic factor is controversy. Various results are due to the different methods of study regarding patients' selection, immunohistochemical techniques used and the quantifying systems for immunoreactions. AIM: Assessment of p53-immunohistochemical expression in 61 patients with gastric carcinomas and the correlation with clinicopathological factors (gender, age, location, macroscopic, and histological type, degree of tumor differentiation and TNM-stage) and patients' survival.
MATERIAL AND METHODS: From the total number of 265 patients (186 males and 79 females) diagnosed with gastric cancer in the period 1998-2002, 61 operated patients were selected. On this group, we performed a prospective study regarding the evolution and aggressiveness of gastric cancer, on a duration of five years. Survival time was calculated from the month of the surgical intervention until the month of death or confirmation of survival, and survival rate was represented by the percentage of survivals at the end of the observed interval (in years and months). We used the monoclonal antibody DO7 that detects the wild and mutant form of p53-protein, by EnVision technique and DAB-visualization. We considered positive reaction only in the presence of brown staining of the nuclei.
RESULTS: P53-immunoreactions were positive in 25 gastric cancers (41%). We obtained positive stainings in 41.9% cases in men and 38.9% women. We found positive p53-immunoreactions in all the carcinomas developed in the upper third of the stomach (100%), in 53.3% of the corporeal tumors, 50% of the pangastric tumors; according to Lauren's classification, we noticed a significantly increased immunoreaction of p53 in the intestinal-type carcinomas. Among histological types, papillary, mucinous, anaplastic and tubular adenocarcinomas presented a relatively increased percentage of p53-positive immunoreactions. P53-positive stainings are more frequently encountered in moderate/poor differentiated carcinomas and those associated with lymphovascular invasion; according to pT- and pN-stage, we remarked a significantly increase of the number of p53-positive cases (p=0.02291 and p=0.038264). Five-year survival rate for patients with p53-positive carcinomas was significantly lower in comparison to the patients p53-negative (8% vs. 22.2%, p=0.0326).
CONCLUSIONS: Immunohistochemical evaluation of p53-protein represents in our study an important prognostic factor, allowing the selection of a group of patients with an aggressive therapeutic indication, such as extensive lymphadenectomy and adjuvant chemotherapy.