Mucoepidermoid Carcinoma: A 23-Year Experience with Emphasis on Low-Grade Tumors with Close/Positive Margins.

Objective Describe outcomes for mucoepidermoid carcinoma by histologic grade and evaluate outcomes for patients with low-grade tumors with close/positive margins after initial surgical resection. Study Design Cohort study. Setting Kaiser Permanente Southern California Medical Group from 1993 to 2016. Subjects and Methods Retrospective review of 154 patients with major and minor salivary gland mucoepidermoid carcinoma of the head and neck. Disease-specific and recurrence-free survival were stratified by tumor grade. Subgroup analysis of recurrence-free survival in patients with low-grade disease with close or positive margins was also performed. Results Five-year recurrence-free and disease-specific survival were excellent for both low- and intermediate-grade tumors, while there was there was a high rate of recurrence and mortality among patients with high-grade tumors. Patients with low-grade tumors with close or positive margins who were observed had no difference in recurrence-free survival compared to those who underwent revision surgery and/or adjuvant radiotherapy. Conclusions High-grade mucoepidermoid carcinoma has poor outcomes despite aggressive treatment. Among patients with low-grade tumors with close or positive margins on initial resection, additional treatment had no impact on survival or recurrence. Observation may be a reasonable alternative to additional treatment in this select group of patients.