3487 - A Retrospective Analysis of 32 Patients with Primary Nasopharyngeal Mucoepidermoid Carcinoma

Purpose/Objective(s): Nasopharyngeal mucoepidermoid carcinoma (NPMEC) is an exceedingly rare subtype of mucoepidermoid carcinoma arising in the nasopharynx.

Materials/Methods: We conducted a retrospective analysis of 32 patients with pathologically confirmed NPMEC diagnosed or treated at Sun Yat-sen University Cancer Center (SYSUCC) between January 2013 and June 2024. Inclusion criteria were: (1) histologically confirmed NPMEC; (2) nasopharyngeal origin confirmed by magnetic resonance imaging (MRI) and/or nasopharyngoscopy; and (3) age >18 years. All tumors were restaged according to the American Joint Committee on Cancer 9th edition staging system for nasopharyngeal carcinoma. Clinicopathological data were extracted from electronic medical records. Survival outcomes—including overall survival (OS), progression-free survival (PFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS)—were calculated from diagnosis to event or last follow-up (August 21, 2025). Kaplan–Meier curves and 5-year survival rates with 95% confidence intervals (CIs) were generated. Univariate Cox regression was used to assess associations between clinicopathological factors and survival. Statistical significance was defined as two-sided P < 0.05.

Results: Among 32 patients with NPMEC, 21 (65.6%) were female, with a median age of 46 years (IQR, 39.5–55 years). Twenty (62.6%) tumors were moderately or poorly differentiated, and 26 (81.2%) presented as stage II–III disease. Notably, plasma EBV DNA was undetectable in all tested cases, and EBV seropositivity (VCA-IgA: 31.3%; EA-IgA: 15.6%) was low, suggesting etiological divergence from endemic NPC. Elevated LDH and CRP levels correlated with advanced T/N stage and clinical stage. Treatment data were available for 23 patients: 9 (39.1%) received surgery-based therapy, while 14 (60.9%) underwent radiotherapy-based regimens. After a median follow-up of 65.8 months, the 5-year overall survival was 85.6% (95% confidence interval [CI]: 61.7%–95.1%), progression-free survival 64.3% (95% CI: 41.0%–80.3%), locoregional recurrence-free survival 64.3% (95% CI: 41.0%–80.3%), and distant metastasis-free survival 81.1% (95% CI: 57.2%–92.5%). Locoregional recurrence was the predominant failure pattern (n=14), with only 3 distant metastases observed. Univariate analysis revealed no statistically significant prognostic factors, though trends suggested worse outcomes with advanced stage, elevated LDH, and radiotherapy-based treatment.

Conclusion: MPMEC is a rare EBV-negative malignancy distinct from endemic nasopharyngeal carcinoma, with locoregional recurrence as the primary pattern of failure. Our data suggest that advanced stage and elevated LDH treatment may be associated with poorer outcomes. Our findings support considering surgery as a potential option for locoregional control, though definitive conclusions require larger collaborative studies.