Epithelial-Myoepithelial Carcinoma of the Salivary Glands: An Analysis of 246 Cases

Abstract

Objectives:

Epithelial-myoepithelial carcinoma (EMC) is a rare neoplasm of the salivary glands. In this study we aim to analyze the clinical features of EMC using national registry data.

Methods:

Retrospective cohort study. The Surveillance, Epidemiology, and End Results (SEER) database was queried. Data were analyzed with respect to various demographic and clinicopathologic factors. Survival was analyzed using the Kaplan-Meier and Cox proportional hazards models.

Results:

A total of 246 cases were available for frequency analysis and 189 for survival analysis. Mean age at diagnosis was 63.8 (±15.4) years. EMC affected females more frequently (57.3%). Distant metastases were present in only 4.5% of cases. Overall disease-specific survival (DSS) at 15 years was 80.2%. Patients with low-grade histology had better DSS at 10 years than those with high-grade tumors (96.2% vs 71.0%, P = .0124). Tumors >4 cm exhibited the worst DSS at 15 years (64.5%, P = .0009). In the survival analysis cohort, all but 6 patients underwent surgery, and a total of 78 (41.3%) received adjuvant radiation therapy (RT). However, no survival benefit was noted for patients who received RT when compared with those who did not (P = .4594). Although a trend toward higher survival with RT (97.1% vs 83.5% without) was observed when high tumor grade and size >4 cm were excluded, it was not statistically significant (P = .2058).

Conclusions:

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 RT in addition to surgery, with no apparent added survival benefit.