Changing frequency of parotid gland neoplasms--analysis of 560 tumours treated in a district general hospital.

An analysis of all parotidectomies performed for neoplastic lesions in the maxillofacial unit at a district general hospital during a 26-year period between 1974-1999 was undertaken. The details analysed were age, sex, histology and temporal variations in the frequency of specific tumour types during the study period. A total of 538 parotidectomies performed on 529 patients in whom 560 tumours were present, formed the basis of this study. Marked variations were present in the age and sex distribution and relative frequency of specific tumour types in this study, when compared to previous reports. There were also differences in the age and sex distribution of pleomorphic adenoma and adenolymphoma (P <0.0001) in this study. The relative frequency of benign tumours and adenolymphoma increased, whereas that of pleomorphic adenoma decreased during the study period. In addition, there was a statistically significant decrease in the relative frequency of pleomorphic adenoma (P <0.0001) and an increase in adenolymphoma (P <0.0001) when comparisons were made with previous studies. This study from a defined population may be more representative of the true proportion of specific tumours in this population. The potential implications of the results on the investigation and treatment of parotid neoplasms is highlighted.