Smokeless tobacco and risk of head and neck cancer: evidence from a case-control study in New England.

Current studies suggesting that smokeless tobacco use increases the risk of head and neck cancer are hampered by small numbers. Consequently, there remains uncertainty in the magnitude and significance of this risk. We examined the relationship between smokeless tobacco use and head and neck squamous cell carcinoma (HNSCC) in a population-based case-control study with 1,046 cases and 1,239 frequency-matched controls. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (95% CI), adjusting for age, gender, race, education level, cigarette smoking, and alcohol consumption. A nonsignificant elevated association between having ever used smokeless tobacco and HNSCC risk (OR = 1.20, 95% CI: 0.67-2.16) was observed. Individuals who reported 10 or more years of smokeless tobacco use had a significantly elevated risk of HNSCC (OR = 4.06, 95% CI: 1.31-12.64), compared to never users. In an analysis restricted to never cigarette smokers, a statistically significant association was observed between ever use of smokeless tobacco and the risk of HNSCC (OR = 4.21, 95% CI: 1.01-17.57). These findings suggest that long-term use of smokeless tobacco increases the risk of HNSCC.