Immunohistochemical analysis of cathepsin-D in benign and malignant salivary gland neoplasms. Evaluation of its role as a prognostic indicator

BACKGROUND: Salivary gland tumors are histologically the most heterogeneous group of tumors. Traditional diagnostics and grading of these tumors often fail to provide any insight into patient's clinical course. Cathepsin-D is a lysosomal acid protease secreted in increased levels in several malignancies. However, its role in salivary gland tumors has not been studied extensively. The present study aims to assess the expression of cathepsin-D in malignant and benign salivary gland tumors and to compare its expression in these tumors. MATERIALS AND METHODS: A total of 40 salivary gland tumors which included 10 cases each of adenoid cystic carcinoma, mucoepidermoid carcinoma, pleomorphic adenoma and Warthin's tumor were evaluated immunohistochemically for cathepsin-D expression. Intergroup comparison of cathepsin-D expression was done between the benign and malignant groups using the Mann–Whitney U-test. Intragroup comparison was also done using Kruskal–Wallis test. RESULTS: A statistically significant difference in the expression of cathepsin-D was observed between the benign and malignant groups. The malignant group showed a considerably higher cathepsin-D expression (mean value 6.284 ± 4.377) when compared to the benign group (mean value 2.281 ± 2.459). The differences in the immunopositivity between the malignant and benign groups were found to be highly significant (P = 0.004). CONCLUSIONS: Increased expression of cathepsin-D is observed in the malignant salivary gland neoplasms. This may prove to be a useful marker for the aggressive biologic behavior as well as invasive potential of salivary gland neoplasms.