Malignant parotid tumors: natural history and treatment.

Sixty-seven cases of histologically proven malignant parotid tumors are presented. Forty percent of the tumors were differentiated adenocarcinoma, while malignant mixed tumors (or pleomorphic adenocarcinomas) formed 18%. The remaining types of malignant salivary tumors are also represented in the series. The natural history and spread of these tumors are studied in detail, with lymph-node metastasis occurring in 25% of the cases and distant metastasis in 20%. Malignant tumors involve largely the retromandibular portion of the parotid gland in over 40% of the cases and the preauricular portion in about one-fifth of the cases. Both regions are affected in a further fifth of the cases. A combination of surgery and radiotherapy was the method employed for curative therapy, with radiotherapy alone reserved mainly for palliation. While the overall five-year survival was 42%, late recurrences constitute a serious problem with eventual demise of about half of these patients. Various factors affecting the prognosis, including histological type of tumor, method of treatment and response to radiotherapy are discussed.