Epidemiology of Warthin's tumour of the parotid gland in an Asian population

Background: Recent studies have documented a number of changing demographic features in the occurrence of Warthin's tumour (adenolymphoma) of the paro tid gland. In order to analyse its epidemiology in an Asian population, a r etrospective study was performed on all parotid neoplasms (n = 289) operate d on between 1988 and 1998. Patients and methods: A total of 209 consecutive patients were selected for study, 136 with pleomorphic adenomas (one bilateral) and 73 with Warthin's tumours (seven bilateral). Patients were analysed with regard to tumour in cidence, age, sex and race. Smoking as an aetiological factor in the develo pment of Warthin's tumour was also studied. Results: Warthin's tumour formed 25 per cent of parotid tumours and its rat io to pleomorphic adenomas was 1 : 1.9. Multicentricity was found in 14 pat ients (19 per cent). The male : female ratio for Warthin's tumours was 4.6 : 1. The proportion of Warthin's tumours did not show any increasing trend relative to pleomorphic adenomas. The racial distribution of Warthin's tumo urs showed an increased incidence among Chinese and a reduced incidence amo ng Malays and Indians. The adjusted odds ratio for sex and age favouring an association between smoking and Warthin's tumour was 39.5 (95 per cent con fidence interval 10.5-149.0; P < 0.0001). Conclusion: The incidence of Warthin's tumour is considerable among Asians although there is still male predominance. There is no rising incidence of Warthin's tumour; the trend parallels the declining smoking rate in the pop ulation. The lower incidence among ethnic groups with dark skin seems to su ggest concomitant genetic factors other than environmental factors alone in histogenesis. Smokers have a 40-fold greater risk than non-smokers of deve loping a Warthin's tumour.