[Clinical study of parotid tumors: a 20 year statistical analysis of 633 cases].

During the 20 years from 1977 to 1996, 633 cases underwent excisions of parotid tumors (539 benign and 94 malignant) in the department of Otolaryngology of Kansai Medical University. The incidence of Warthin's tumors in the years from (1987 to 1996) was higher than that in the years from 1977 to 1986. On the other hand, the incidence of mucoepidermoid carcinomas was less than in previous reports. Tumors accompanied with spontaneous pain or facial nerve palsy and with invasion to both lobes frequently indicated malignancy. Facial nerve palsy caused by either benign or malignant tumors before operation showed no improvement after surgery. The incidences of facial nerve palsy (1.0% in benign, and 18.3% in malignant) and Frey's syndrome (17.8% in benign, and 18.3% in malignant) after surgery were lower than those in other reports of both benign and malignant tumors. Five-year mortality was 76.1%. All deaths that occurred five years after operation involved highly grade malignant tumors.