Synergistic effects with alcohol
Tobacco smoking and alcohol use play an etiological role in oral cancer development.
Various studies have shown that a causative relationship exists between oral cancer and
the heavy intake of alcohol and that the combination of tobacco and alcohol use raises
the risk for oral cancer significantly more than the use of either substance alone.101,102
The joint effect of both behaviours is two to three times greater than the individual effects
of smoking and drinking.103,104,105 Heavy drinkers who also smoke have 38 times the
risk of oral cancer compared to non-smokers who do not drink.106 Alcohol increases the
permeability of the oral mucous membranes which is thought to enhance the carcinogenic
effect of tobacco based products.
It has been estimated that smoking and drinking combined account for about 75% of all
oral and pharyngeal cancers in the United States.106 There is also evidence for a possible synergistic effect with dietary factors. For example, the odds of squamous cell carcinoma
of the oesophagus and oral/pharyngeal cancer is higher among those with low vitamin D
intake, and even greater among those with low vitamin D intake who are heavy current
smokers and consumers of alcohol