Alcohol drinking and total cancer risk: An evaluation based on a systematic review of epidemiologic evidence among the Japanese population

Background: We conducted a systematic review of epidemiological evidence to evaluate the association between alcohol drinking and total cancer risk among the Japanese population. Methods: Original data were obtained from MEDLINE searches using PubMed or from searches of the Ichushi database, complemented with manual searches. Evaluation of associations was based on the strength of evidence and the magnitude of association, together with biological plausibility as previously evaluated by the International Agency of Research on Cancer. Results: Of eight cohort studies identified, six studies, three of which included women, were subjected to evaluation. In men, all six studies showed a weak to moderate positive association between alcohol drinking and total cancer risk. While light drinking had little effect on total cancer risk, heavy drinking of more than 46-69 g of alcohol per day contributed to total cancer risk for most of these Japanese populations. However, no association was reported in women in any of the three studies. Conclusion: We conclude that there is convincing evidence that alcohol drinking increases the risk of total cancer in the Japanese population, specifically among heavy drinking men.