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 (≥ 2.0), it was 5.8 (4.6-7.2); for smoking and the AST/ALT ratio (≥ 2.0), it was 6.3 (5.1-7.5). Similar results were seen for mortality from esophageal cancer. Subjects who drank ≥ 25 g/day with an AST/ALT ratio ≥ 2 had a higher risk of esophageal cancer incidence (HR = 6.5, 4.8 to 8.7) compared with those who drank ≥ 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.