Introduction: Her-2/neu overexpression has been recently shown to be a poor prognostic factor in breast carcinoma. Overexpression has also been demonstrated in adenocarcinoma of the pancreas but the significance is unclear. We attempted to study the role of Her-2/neu overexpression, detected by immunohistochemistry, in pancreatic carcinoma and also examined for variability of overexpression across different tissue sections on individual tumor specimen.
Materials and methods: Records of all patients with adenocarcinoma of the pancreas, diagnosed and followed between 1986 and 2001 at a tertiary care oncology center were reviewed. Archival pathological samples were analyzed for Her-2/neu expression using the Hercep immunohistochemical assay (DAKO). A score of 2+ or greater on the assay was considered positive for Her-2/neu expression. When tumors were found to be Her-2/neu-positive, they were assessed for variability of expression of Her-2/neu by staining different sections of individual tumor blocks. Log-rank tests and Cox proportional hazards methods were used to analyze survival data.
Results: Three hundred and eight patients were included in our study. The mean age was 70 years. Forty-eight out of 308 specimens (16%) were positive for Her-2/neu expression. The mean survival in the Her-2/neu-positive group was 11 months and in the Her-2/neu-negative group was 7 months (p=.03). Of the 48 patients with Her-2/neu-positive tumors, 16 showed variable overexpression (33%). Multivariate analysis did not reveal statistical difference in survival between the uniformly expressing and variably expressing tumors.
Conclusion: Her-2/neu overexpression detected by immunohistochemistry does not appear to be a poor prognostic factor in patients with adenocarcinoma of the pancreas. Also, there is significant variability in the level of Her-2/neu expression across tumor sections in individual patients, which can potentially lead to considerable misclassification. Hence, we believe that, pending further studies, Her-2/neu may not be an appropriate target for therapy in pancreatic adenocarcinoma.