Alcohol related cancers in Scotland
Introduction: There is considerable epidemiologic evidence that drinking alcoholic beverages is associated with an increased risk for certain cancers (i.e. cancers of the upper-aero digestive tract) though the evidence of an increased risk for colorectal and breast cancer is controversial. For other cancers (e.g. kidney, bladder, lung, ovarian) the evidence remains inconclusive. Considering the high prevalence of many of these cancers in Scotland, even a small increase in cancer risk is of great importance, therefore from a public health perspective it is important that the evidence linking alcohol to an increased risk of cancer is continuously evaluated. Questions still remain, however, concerning the robustness and consistency of the alcohol information collected across studies. Furthermore, the heterogeneity of drinking levels, drinking patterns, and definitions of standard drinks internationally make it problematic to generalise the findings of these studies. Aim: To further clarify the role of alcohol in the occurrence of cancer in a country marked by high levels of alcohol consumption and rising incidence of many of the cancers linked with alcohol consumption. The aim of this study, therefore, is to (1) investigate the association between alcohol consumption and the risk of fourteen cancers using routine Scottish data sources and (2) to test the hypothesis that alcohol consumption increases the risk of these cancers in a sample of the Scottish population. Methods: A systematic review of the published literature between 1999, the date of the last major review, and 2009 on alcohol related cancers to determine the strength of evidence on the association between alcohol and cancer, and if it varies by amount drunk, by drinking pattern and drink type. Two cohort studies were formed; in the first a population based cohort study, based on a linkage between a representative general population sample and hospital, cancer registry and death records in Scotland, describes risk of cancer by amount of alcohol consumed per week and by drinking frequency and in a second study, based on a linkage between hospital and cancer and death records, the risk of cancer in a population that has been admitted to hospital (between 1981 and 2007) with an alcohol related diagnosis was investigated. Results: The present study provides weak evidence of a relationship, in a sample of the Scottish general population, between alcohol drinking frequency and amount consumed and cancers of the upper aero digestive tract. An increased risk (though non-significant) of colorectal cancer for daily drinkers was observed but no relationship was detected for amount consumed for this cancer. There was no association observed between drinking frequency or amount consumed and risk of breast, lung and prostate cancer. People with an alcohol-related hospital admission, however, are at substantially higher relative risk of head and neck and upper gastrointestinal cancers compared to the general population, and relative risks increase with increasing levels of deprivation. It is likely that tobacco smoking also contributes to this excess risk. Conclusions: The generalisability of findings from the international literature to Scotland is problematic due to different measures of alcohol consumption. Although the present study provides evidence that people in Scotland who require in-hospital care for an alcohol related condition are at substantial subsequent relative risk of head and neck and upper gastrointestinal cancers and that the relative risk increases with increasing levels of deprivation, further prospective studies with longer-follow-up are required to assess the risk between alcohol consumption and cancer in the Scottish general population.