Histological features and prognosis of patients with mucoepidermoid carcinoma of the parotid gland.

Histological features and prognosis of patients with mucoepidermoid carcinoma of the parotid gland were analysed. Tumours from 13 patients were classified according to histological grades and immunoreactivity for HER-2/neu. Surgical resection of the tumour was performed for all patients, and the overall five-year survival rate was 69 per cent. The patients whose histological grades were 1 or 2 showed a 100 per cent five-year survival rate, but no patient with grade 3 survived five years. Also, patients who had tumours that overexpressed HER-2/neu had a lower survival rate (25 per cent) than patients with tumours that had weaker immunostaining (89 per cent). We considered tumours classified as grade 3 plus strong HER-2/neu expression to be 'high malignancy', and compared them with 'low malignancy' tumours that were grade 1 or 2 and had weaker HER-2/neu staining. Patients with high malignancy tumours had shorter recurrence-free intervals and shorter overall survival than patients with low malignancy tumours. The overall survival period of the low malignancy cases was much longer than the recurrence-free interval; unlike that in the high malignancy tumour patients. These results suggest that the combination of histological grades and expression of HER-2/neu may be a useful predictor of the prognosis for mucoepidermoid carcinomata.