Epithelial-Myoepithelial Carcinoma of the Salivary Glands

Abstract

Objective Epithelial-myoepithelial carcinoma (EMC) is a rare neoplasm of the salivary glands. In this study, we aim to examine the demographic, clinicopathologic, and survival features of EMC using a population-based approach. Study Design and Setting Retrospective cohort study. Subjects and Methods The Surveillance, Epidemiology, and End Result (SEER) database (1973-2010) was queried for EMC of the major salivary glands. Data were analyzed with respect to various demographic and clinicopathologic factors. Survival was analyzed using the Kaplan-Meier and Cox proportional hazards models. Results In total, 246 cases were available for frequency analysis and 207 for survival analysis. Mean ± SD age at diagnosis was 63.8 ± 15.4 years. EMC affected females more frequently (57.3%). Distant metastases were present at diagnosis in only 4.5% of cases. Overall disease-specific survival (DSS) at 60, 120, and 180 months was 91.3%, 90.2%, and 80.7%, respectively. Patients with low-grade histology had significantly better survival at 180 months relative to those with high-grade tumors (90.6% vs 0.0%, P = .0246). When stratified by tumor size, patients with lesions >4 cm had the worst survival at 180 months (58.8%, P = .0003). All but 9 of the 207 cases available for survival analysis underwent surgery. A total of 85 patients (41.1%) received radiotherapy in addition to surgery. No survival benefit was noted for patients who received radiotherapy compared with those who did not ( P = .4832). Conclusion This report represents the largest series of EMC to date. Despite being regarded as a low-grade, indolent tumor, a significant fraction of our cohort underwent radiotherapy in addition to surgery, with no apparent added survival benefit.