In contrast to smoking, health risks associated with alcohol follow a U shaped curve, with modest drinking conferring lower overall levels of risk to health as compared to complete abstention and heavy drinking [73]. However, in many individuals, drinking becomes problematic, either through contributing to accidental injury, or through negative effects on health associated with chronic, heavy intake. The epidemiological link between heavy alcohol use and increased risk of cancer is well established [74]. Interestingly, in contrast to smoking, alcohol-associated cancer risk appears to decline more slowly over time than smoking-associated cancer risk, with 20 or more years required for the risk of head and neck cancers associated with drinking to equal that of abstainers [75]. Both the longevity of risk associated with heavy alcohol use, and its distinct U shaped curve for risk in relation to use pattern suggest that the underlying epigenetic mechanisms at work are distinct from smoking.
