The Importance of Prostate-Specific Membrane Antigen Expression in Salivary Gland Tumors

OBJECTIVE: Prostate-specific membrane antigen (PSMA) is a cell membrane protein expressed by prostate tissues. It is not prostate specific and is also expressed by some non-prostatic solid neoplasms. Our study aimed to investigate the potential role of PSMA in salivary gland tumors. METHODS: The present study was designed to retrospectively analyze our cases that presented with salivary gland tumors. The files of 105 patients were reviewed and their paraffin embedded blocks were retrieved from the pathology department. Immunohistochemical examination and staining were done using PSMA antibody. Tumor tissue PSMA immunohistochemical staining was scored semi-quantitatively with the modified quartile approach. Negative staining was scored 0, >0% and ≤25% tissue expression was considered weak (score 1), >25% and ≤50% tissue expression was considered mild (score 2), >50% and ≤75% tissue expression was considered moderate (score 3), and >75% tissue expression was considered strong (score 4). RESULTS: Eighty-eight patients (55 males, 33 females) were included in the study. Forty-eight patients had pleomorphic adenoma (PA), 35 had Warthin’s tumor (WT), two had mucoepidermoid carcinoma, two had adenoid cystic carcinoma, and one had squamous cell carcinoma. There was statistically significant difference in terms of PSMA expression between PA and WT (p=0.003). PSMA expression was high in PA and absent in WT. CONCLUSION: PSMA is a potential source of inspiration for future studies on the development of novel diagnostic and theranostic investigations of salivary gland tumors. Prospective studies targeting intratumoral PSMA in salivary gland tumors should be planned.