Cigarette smoking is more strongly associated with head and neck cancers than drinking alcohol, according to Mia Hashibe, Ph.D., of the International Agency for Cancer Research in Lyon, France, and colleagues. Their research has found that smoking is responsible for a quarter of head and neck cancers among individuals who do not drink alcohol.
At least 75% of head and neck cancers are caused by a combination of cigarette smoking and drinking alcohol, but researchers have not known the individual contributions of these risk factors because people who smoke are more likely to drink than the general population and vice versa.
In this study, researchers sought to tease out the independent effect of each risk factor on head and neck cancer development. The researchers examined head and neck cancer risk among smokers who never drank alcohol and people who drink but never used tobacco products. They pooled data from 15 case-control studies, which included 10,244 head and neck cancer patients and 15,227 controls. About 16% of the patients and 27% of the controls never drank, and about 11% of the patients and 38% of the controls never smoked.
Among never drinkers, cigarette smoking was associated with an increased risk of head and neck cancer (OR for ever versus never smoking = 2.13, 95% CI = 1.52 to 2.98), and there were clear doseresponse relationships for the frequency, duration, and number of pack-years of cigarette smoking. Approximately 24% (95% CI = 16% to 31%) of head and neck cancer cases among nondrinkers in this study would have been prevented if these individuals had not smoked cigarettes. Among never users of tobacco, alcohol consumption was associated with an increased risk of head and neck cancer only when alcohol was consumed at high frequency (OR for three or more drinks per day versus never drinking = 2.04, 95% CI = 1.29 to 3.21). The association with high-frequency alcohol intake was limited to cancers of the oropharynx/hypopharynx and larynx.
“The major strength of our pooled analyses was assembly of a very large series of never users of tobacco and never drinkers among head and neck cancer patients and control subjects, which allowed us to examine head and neck cancer risks in detail and to explore differences in risks by cancer subsite, geographic region, and sex,” the authors write. The results represent the most precise estimates available of the independent association of each of the two main risk factors of head and neck cancer, and they exemplify the strengths of large-scale consortia in cancer epidemiology, the authors state.
Source: “Alcohol Drinking in Never Users of Tobacco, Cigarette Smoking in Never Drinkers, and the Risk of Head and Neck Cancer: Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium” JNCI Journal of the National Cancer Institute 2007 99(10):777-789; doi:10.1093/jnci/djk179