Previous scientific research has shown that heavy alcohol consumption is a major risk factor for upper aero-digestive cancers, and even light drinking increases slightly the risk of breast cancer in women. The present study is based on a very small number of cases of cancer in New Zealand, tabulated separately for Maori and non-Maori subjects, and applies estimates of alcohol effects from other population-based studies. Besides having so few cases, the investigators had no individual data (on the pattern of alcohol consumption, type of beverage, smoking or other lifestyle habits, socio-economic status, etc.) on subjects who did, or did not, develop these cancers. It is not even known whether or not the specific subjects who developed these cancers consumed alcohol.
It has repeatedly been emphasized that disease-specific death rates must be interpreted in light of the effects of the exposure (in this case, alcohol consumption) on other causes of death as well, especially on total mortality risk. The large majority of studies have shown that moderate drinking clearly reduces the risk of most cardiovascular diseases, diabetes, and other of the diseases of ageing, as well as the risk of total mortality. However, the estimated effects of alcohol on total mortality are not included in this paper.
The very long Discussion in this paper is primarily a treatise on how the public must be told of the dangers of cancer from any alcohol consumption; it focuses on health policy recommendations and very little on the limitations of the data and the study. The authors end up making very broad recommendations based on very small numbers of subjects. Limitations to this study suggest that it adds little to our current understanding of the relation of alcohol consumption to the risk of cancer and other diseases.
Reference: Connor J, Kydd R, Maclennan B, Shield K, Rehm J. Alcohol-attributable cancer deaths under 80 years of age in New Zealand. Drug and Alcohol Review 2016; pre-publication. DOI: 10.1111/dar.12443