Prognostic factors in primary salivary gland mucoepidermoid carcinoma: an analysis of 376 cases in an Eastern Chinese population

Mucoepidermoid carcinoma (MEC) is an infrequent malignant neoplasm that originates most commonly in the salivary glands. The present study aimed to provide new information on prognostic factors in patients with salivary gland MEC. A retrospective analysis of the medical records of patients diagnosed with primary salivary gland MEC between 2003 and 2010 was conducted. The incidence of MEC in the minor salivary glands (62.2%) was almost twice that in the major salivary glands (37.8%). The most frequently affected sites were the parotid gland and palate. Lymph node metastasis was reported more frequently in male than female patients (P = 0.02), in high-grade than low/intermediate grade lesions (P < 0.001), and in lesions involving the submandibular gland (P < 0.001). The disease-free survival (DFS) at 5 years was 80.47%, with rates of 98.0%, 86.5%, and 38.5% for low-, intermediate-, and high-grade tumours, respectively. Among various clinicopathological factors, the only independent prognostic factor was histological grade (P < 0.001). Primary tumour site and histological grade are two important factors affecting cervical lymph node metastasis. Histological grade is the only independent factor affecting survival beyond tumor lymph node metastasis (TNM) staging in salivary gland MEC. Further advances in therapy are needed to improve the outcomes for patients with high-grade lesions.