Background: Overexpression of c-erbB-2 protein in breast cancer has been reported to be associated with poor prognosis. However, clinical significance of c-erbB-2 protein overexpression has not been demonstrated clearly in gastric cancer.
Methods: Immunohistochemical reactivity to c-erbB-2 protein was examined in formalin-fixed, paraffin-embedded tissue sections from patients with gastric cancer.
Results: First, primary stomach cancers in 106 patients were examined. Among 58 cases of papillary or well- to moderately differentiated tubular adenocarcinoma, staining of c-erbB-2 protein was positive on the plasma membrane of cancer cells in 8 cases (14%). Conversely, among 47 cases of poorly differentiated adenocarcinoma or signet ring cell carcinoma, positive staining of c-erbB-2 protein was detected in one case only (2%), where the histopathologic type was poorly differentiated adenocarcinoma with a cohesive structure. Among tubular adenocarcinomas, no significant association was shown between overexpression of c-erbB-2 protein and the depth of tumor invasion, extent of lymph node metastasis, or tumor location. To investigate the correlation between the staining of c-erbB-2 protein and prognosis in gastric cancer, an additional 108 cases of papillary or well- to moderately differentiated tubular adenocarcinoma invasive as far as the muscularis propria were examined immunohistochemically for expression of c-erbB-2 protein. Twelve cases (11%) showed positive staining on the plasma membrane, and their survival curve showed a significantly poorer prognosis (P < 0.01).
Conclusions: These results suggest that overexpression of c-erbB-2 protein occurs selectively in cohesive gastric cancer, and it can be considered an important prognostic indicator.