Evaluation of HER2/neu expression in different types of salivary gland tumors: systematic review

Abstract

Introduction: Salivary gland tumors comprise a major part of head and neck tumors and encompass a variety of lesions with various subgroups. On the other hand it is well known that carcinogenesis is a result of mutations and over-expression of specific proteins. One of these markers is HER2 which is used as a prognostic factor in many cancers such as breast cancer. Purpose: Given the significance of HER2 marker in diagnosis and prognosis of salivary gland tumors we decided to do a systematic review and meta-analysis on the over-expression of this marker in this group of cancers. Materials and method: Databases were searched, including PubMed (Medline), Scopus, CINHAL, Psycoinfo, the Cochrane library and ProQuest . the meta-analysis was carried out based on the data of 80 studies. Results: The over expression rate of HER2 marker in malignant and benign tumors ranges from 3.3 to 84% and 1 to 9% respectively. The highest rate of expression among the malignant tumors subgroups which is presented as pooled positive rate belonged to salivary duct carcinoma which was 45%( CI 95% 21.9- 70.3) . However the overall highest rate was in high grade muco epidermoid carcinoma ( 84% with CI 95% 74.1 - 90) . The expression of the marker in benign tumors was significantly less than malignant tumors and the highest rate belonged to myoepithelioma with a pooled positive rate of 9%(CI 95% : 1.7- 33.6) Conclusion: The over-expression of the marker is specifically higher in muco epidermoid carcinoma, salivary duct carcinoma and ex pleomorphic adenocarcinoma subtypes of malignant tumors. Similar to the role of this marker in defining prognosis of breast cancer, it can be applied to salivary gland tumors as well. Nevertheless, in highly aggressive tumors such as salivary duct carcinoma with lower rate of response to conventional treatments, molecular target therapy can play a promising role. In this regard, HER2 marker which is found in malignant tumors of salivary gland, can be considered as a target in the treatment of these lesions