Introduction: Primary mucoepidermoid carcinoma (MEC) of the esophagus is an uncommon neoplasm characterized by a diffuse mixture of squamous and mucus-secreting glandular carcinoma cells. Its biological behavior and response to therapies have not been well studied. Surgical resection is still the primary treatment, but the prognosis is poor. This retrospective study was designed to investigate the clinical characteristics, diagnosis, treatment, and prognosis of primary esophageal MEC.
Methods: Clinical data were retrospectively analyzed from 36 patients with pathologically confirmed primary esophageal MEC who underwent transthoracic esophagectomy with lymphadenectomy between January 1991 and June 2010 at the Cancer Hospital of Shantou University Medical College. There were 27 men and 9 women ranging in age from 40 to 78 years (median, 58 years). Twenty-six of the 36 patients were treated with surgery alone. The other 10 were treated with surgery plus postoperative radiotherapy. The Kaplan-Meier and log-rank methods were used to estimate and compare survival rates. Cox's hazard regression model was used to identify prognostic factors, with entry factors of gender, age (≤60 years versus >60 years), length of the primary lesion (≤5 cm versus >5 cm), location of the primary lesion, macroscopic tumor type, tumor cell differentiation, pT, pN, pTNM stage, operation type (radical/palliative), and radiotherapy (yes/no).
Results: The clinical symptoms, radiological and endoscopic features of primary esophageal MEC were similar to those of esophageal squamous cell carcinoma (ESCC). Of the 20 cases who underwent preoperative endoscopic biopsy, 18 cases were misdiagnosed as ESCC and 2 were misdiagnosed as esophageal adenosquamous carcinoma. The mean follow-up duration of this series was 38.8 months (range, 3-142 months). Twenty-two patients had died, 12 were still alive, and 2 were lost to follow-up. The median survival time of the 36 patients was 29.0 months (95% confidence interval = 20.0-38.0), and the 1-, 2-, 3-, and 5-year overall survival rates were 80.6%, 57.1%, 34.4%, and 25.8%, respectively. The 5-year survival rate of 25.8% was lower than 5-year absolute survival rate of 39.2% for ESCC patients who had undergone surgical resection during the same period at our center. For patients who underwent a radical operation, the 5-year survival rate of 32.0% for MEC patients was also lower than that of 41.7% (908/2175) for ESCC patients. In univariate analysis, pN (pN0/pN1-3) (p = 0.003) and operation type (radical/palliative) (p = 0.006) significantly influenced the median survival time of MEC patients. In multivariate analysis, pN (pN0/pN1-3) (p = 0.002) and operation type (radical/palliative) (p = 0.004) were independent prognostic factors.
Conclusions: Primary esophageal MEC is a rare disease and prone to be misdiagnosed. Lymph node metastasis and operation are independent prognostic factors. Surgical resection is the primary treatment, but the prognosis is poor.