Expression of Bax protein in gastric carcinomas. A clinicopathological and immunohistochemical study

Background and study aims : Reduced Bax protein expression has been shown to be a negative prognostic factor in patients with breast, ovarian, colorectal, esophageal and pancreatic cancer. Our aim was to immunohistochemically study Bax protein expression in gastric carcinomas and correlate its expression with clinicopathological parameters and prognosis. Patients and methods : Immunohistochemistry was performed, using a monoclonal antibody against bax, in paraffin-embedded tumor specimens from 47 cases of gastric cancer. Results : Positive staining for the Bax protein was found in 20/47 (42.4%) adenocarcinomas examined. Negative Bax protein expression in tumour cells was correlated with lymph node metastasis (P < 0.05), and degree of differentiation (p<0.05). Univariate analysis showed that the variables with a significant negative impact on survival were : high TNM tumour stage, depth of penetration in the gastric wall, lymph node involvement, and Bax protein expression. Multivariate analysis showed that the only variable with an impact on survival was Bax protein expression (p<0.05, Relative Risk: 3.34). Kaplan-Meier curves showed that the 5-year survival was 36.8% in cases with positive compared with 16% in cases with negative Bax protein expression (p=0.0427). Conclusion : Negative Bax expression in gastric cancer is associated with de-differentiation, lymph node metastases, and poor clinical prognosis. Bax protein expression might play an important role in the development and phenotypic differentiation of gastric carcinomas and tumor progression.