Clinical investigation of malignant parotid tumors

We reviewed 55 cases of previously untreated malignant tumors arising in the parotid gland treated between Jan 1989 and May 2008. Histopathologically, we observed 13 tumor types, the most frequent histological type being mucoepidermoid carcinoma (12), followed by adenoid cystic carcinoma (11). According to clinical stage, 5 subjects were classified as T1, 18 as T2, 10 as T3, and 22 as T4. N+ cases numbered 7, and were staged as N2. Six had distant metastasis (5 lung and 1 axillary). Nineteen exhibited facial nerve palsy before treatment. Among major therapies, surgery was conducted in 50 subjects, radiation therapy in 3, and chemotherapy, and percutaneous ethanol injection therapy in each. Overall five-year survival determined using the Kaplan-Meier method was 73%. Among major histopathological types, five-year survival was 33% for undifferentiated carcinoma, 40% for adenocarcinoma, 62% for mucoepidermoid carcinoma, 67% for carcinoma in pleomorphic adenoma, and 100% for adenoid cystic carcinoma and acinic cell carcinoma. By T classification, five-year survival was 100% for T1, 88% for T2, 90% for T3, and 44% for T4. Five-year survival was 36% for those exhibiting facial nerve palsy and 94% for non palsy. Factors influencing poor outcome were T4 (p=0.001) and facial nerve palsy (p=0.001). (author)