Smoking and risk of parotid gland tumors: a nationwide case-control study.

BACKGROUND: Because existing data regarding the relation between smoking and salivary gland tumors are sparse, tobacco is currently not classified as a salivary gland carcinogen. The objective of the current study was to assess the association between smoking and benign and malignant parotid gland tumors (PGTs) in a nationwide study. METHODS: The sample included 459 patients with incident PGT, aged > or =18 years, who were diagnosed between 2001 and 2003 and a group of 1265 individually matched, population-based controls. Analyses of the risk of PGT associated with various smoking variables were performed by using conditional logistic regression. Data also were stratified by histologic type; statistical significance tests were 2-sided. RESULTS: Ever smoking cigarettes was associated with an odds ratio (OR) of 1.66 (95% confidence interval [95% CI], 1.31-2.11) for developing a PGT. The risk was strongest for early ages at smoking initiation, and trends of increasing risk were observed with increasing smoking intensity, pack-years, latent period, and smoking duration (P for trend <.001 for each). Analysis by histologic type indicated remarkably high risks for Warthin tumor (OR for ever cigarette smokers: 15.3; 95% CI, 6.1-38.5). For pleomorphic adenomas and malignant tumors, the risks associated with ever smoking were 1.01 (95% CI, 0.75-1.37) and 1.69 (95% CI, 0.81-3.51), respectively. CONCLUSIONS: Smoking plays an important role in the development of Warthin tumor. Although no association was observed for pleomorphic adenoma, the possible indication of increased risk of malignant tumors requires further investigation in larger studies.