Primary and metastatic cancer of the parotid: comparison of clinical behavior in 232 cases.

Abstract

Parotid malignancy may develop as a primary cancer of salivary tissue or by metastatic involvement of parotid lymph nodes. The aim of the study was to compare the clinical behavior of primary and metastatic parotid cancers by analyzing patterns of treatment failure and clinical outcomes. Retrospective review of clinical and pathologic data prospectively accessioned onto a computerized database. A prospectively documented series of 232 parotidectomies carried out for treatment of cancer from 1988 to 1999 was reviewed. There were 177 male and 55 female patients with a median age of 65 years (age range, 17-97 y). Median follow-up time was 4 years. Pathological groups included 54 patients with primary parotid cancer, 101 with metastatic cutaneous squamous cell carcinoma, 69 with metastatic melanoma, and 8 with other metastatic cancers. Neck nodes were clinically positive in 12 patients with primary cancer, 24 patients with squamous cell carcinoma, 16 with melanoma, and 2 with other metastatic malignancies. Conservative parotidectomy, preserving the main trunk of the facial nerve, was performed in 185 patients, and 47 patients had a radical parotidectomy sacrificing the facial nerve. There were 54 therapeutic and 110 elective neck dissections. Adjuvant radiotherapy was given to 39 patients with primary cancer, 86 with squamous cell carcinoma, 50 with melanoma, and 8 in the other metastatic group (78% of the patients in the series). Local control rates at 5 years in the four groups were 86%, 75%, 94%, and 100%, respectively (P <.01). Survival rates at 5 years were 77%, 65%, 46%, and 56%, respectively (P <.01). The pattern of parotid malignancy is unique in Australia because of the high incidence of skin cancer, which can metastasize to the parotid gland. Metastatic cutaneous malignancy predominates. The pattern of failure and outcome varied depending on histological findings. Local failure occurred most often in metastatic squamous cell carcinoma, whereas patients with melanoma had the highest incidence of distant spread.