[Chemoprevention of esophageal squamous cell carcinoma--clinical trials]

Esophageal squamous cell carcinoma is one of the most lethal malignances of digestive tract. Epidemiological data confirmed influence of the diet especially Mediterranean one that decreases the risk of cancer. High consumption of fresh vegetables and fruits, mainly citrus and tea drinking, also has a beneficial effect on decreasing incidence of the cancer. High intake of various antioxidants and natural fibers found in the plant diet as well as prolonged administration of cyclooxygenase-inhibitors, especially aspirin, plays also a protective role. Results of sparse, prospective, randomized trials on chemoprevention of esophageal squamous cell carcinoma are not so unequivocal. Supplementation of six traditional Chinese herbs, retinamide and riboflavin provided the most promising effects, but intake of multiple vitamins and minerals, including calcium and decaffeinated green tea, was ineffective. However, the studies were performed on small populations inhabiting select Chinese provinces known for their high esophageal cancer incidence. Due to a number of limitations, the collected data cannot be compared directly to other populations who are exposed to different environmental factors and with different genetic predispositions.