The Independent Effects of Cigarette Smoking, Alcohol Consumption, and Serum Aspartate Aminotransferase on the Alanine Aminotransferase Ratio in Korean Men for the Risk for Esophageal Cancer

PURPOSE The goal of this study is to assess the interactions among alcohol consumption, cigarette smoking, and aspartate aminotransferase (AST) / alanine aminotransferase (ALT) ratios on esophageal cancer. MATERIALS AND METHODS Alcohol and the risk of incidence and death from esophageal cancer were examined in a 14-year prospective cohort study of 782,632 Korean men, 30 to 93 years of age, who received health insurance from the National Health Insurance Corporation and had a medical evaluation from 1992 to 1995. RESULTS Smoking, alcohol intake, and AST/ALT ratios were associated with the increased risk of esophageal cancer in a dose-dependent manner independent of each other. Smoking was associated with an increased risk of incidence [Hazard ratio (HR) = 2.2, 95% CI = 1.8 to 2.5] and mortality (HR = 2.5, 2.0 to 3.1). Combined HR of incidence for alcohol consumption (> 25 g/day) and smoking was 4.5 (3.8-5.5); for alcohol (> 25 g/day) and the AST/ALT ratio (>or= 2.0), it was 5.8 (4.6-7.2); for smoking and the AST/ALT ratio (>or= 2.0), it was 6.3 (5.1-7.5). Similar results were seen for mortality from esophageal cancer. Subjects who drank >or= 25 g/day with an AST/ALT ratio >or= 2 had a higher risk of esophageal cancer incidence (HR = 6.5, 4.8 to 8.7) compared with those who drank >or= 25 g/day with an AST/ALT ratio < 2 (HR = 2.2, 1.9 to 2.6). CONCLUSION Alcohol, smoking, and the AST/ALT ratio are independently associated with increased risk of esophageal cancer but did not interact synergistically. The combination of the AST/ALT ratio with a questionnaire for alcohol consumption may increase the effectiveness for determining the risk of esophageal cancer.