Prognostic indicators for malignant tumours of the parotid gland.

Abstract

The best treatment of malignant parotid tumours still remains to be defined, and a better knowledge about the tumour features that predict the treatment result is needed. The histological classification of parotid tumours may present difficulties on account of their great morphological diversity. In a series of 152 patients with a malignant tumour of the parotid gland, the prognostic factors and treatment results were investigated over a 25-year period. Treatment consisted of surgery, radiation therapy or a combination (49%, 13% and 38% respectively). Crude 5-year survival was 50% with significant differences related to stage (stage I, 65%; stage II, 50%; stage III, 21%; and stage IV, 9%). With respect to histopathology, the adenoid cystic carcinomas and the acinic cell carcinomas had the best prognosis (76% and 67% 5-year crude survival and 53% and 67% 10-year crude survival respectively). There was a significant difference in crude survival between well/intermediate and poorly differentiated tumours (P = 0.007). In a Cox hazard regression analysis including 136 patients and using death from cancer as the end-point, the following parameters were independent prognostic predictors: T-classification (P = 0.002), M-classification (P < 0.0001), N-classification (N+versus N0) (P = 0.005), local invasion (P = 0.003) and histological differentiation of the tumour (P = 0.03). The TNM system is a good predictor of treatment outcome for malignant parotid tumours. The use of a combination of clinical and histological factors will assist the design of treatment strategies for parotid gland tumours.