Vegetables, fruits, related dietary antioxidants, and risk of squamous cell carcinoma of the esophagus: a case-control study in Uruguay.

In 1998-1999, a case-control study on esophageal cancer was conducted in Uruguay. For this purpose, 111 cases with squamous cell carcinoma of the esophagus and 444 controls with conditions unrelated to tobacco smoking, alcohol drinking, or recent changes in the diet were frequency matched on age, gender, residence, and urban/rural status. Vegetables and, more markedly, fruits were associated with strong reductions in risk. On the other hand, 12 of 15 dietary antioxidants displayed significant inverse associations with esophageal cancer risk. The strongest effect was observed for high intake of beta-cryptoxanthin (odds ratio = 0.16, 95% confidence interval = 0.08-0.36). Also, alpha-carotene, lycopene, and beta-sitosterol were associated with significant reductions in risk. Most antioxidants lost their effect when they were further adjusted for a term for all vegetables and fruits. beta-Carotene showed an increased risk with high intakes. On the other hand, vegetables and fruits remained as significant variables after adjustment for each antioxidant, suggesting that other substances or other mechanisms could explain this effect.