Risk factors for esophageal cancer in Shanghai, China. II. Role of diet and nutrients.

A population-based case-control study of esophageal cancer (902 cases, 1,552 controls) in Shanghai, China, investigated the etiologic role of diet. After adjustment for cigarette smoking, alcohol consumption and other risk factors, increasing consumption of fruits, dark orange vegetables and beef or mutton was associated with statistically significant decreasing trends in risk for esophageal cancer. In general, risks were about 40% lower among those in the upper vs. lower quartiles of intake of these foods. Fivefold increases in risk were observed among those who consumed burning hot soup or porridge, with smaller excesses for preserved vegetables, salty and deep fried foods. Nutrient analysis revealed that increased dietary intake of protein, carotene, vitamins C and E and riboflavin was associated with reduced esophageal cancer risk. Our findings support the notion that the reported temporal increases in the per capita consumption of fruits, vegetables and animal products contribute to the substantial reduction in the incidence of esophageal cancer in Shanghai, particularly since cigarette and alcohol use has not decreased.