[Medicamentous inhibitory therapy of precancerous lesions of the esophagus--3 and 5 year inhibitory effect of antitumor B, retinamide and riboflavin]

Abstract

9633 subjects aged 40 to 65 were sampled from high-risk areas for esophageal cancer and examined by esophageal exfoliative cytology. 2531 and 3393 cases of markedly and mildly dysplastic patients were screened out respectively. Those with marked dysplasia were randomized into 3 groups and given respective medications: antitumor B (Chinese herbs), 4-ethoxycarbophenylretinamide (retinamide) and placebo. The subjects with mild dysplasia were randomly divided into 2 groups for riboflavin and placebo treatment. After medication for 3 or 5 years the subjects were reexamined by esophageal exfoliative cytology. The incidence of esophageal cancer in the antitumor B group after taking medication for 3 and 5 years was reduced by 52.2% and 47.3% respectively as compared with the placebo group. These differences were statistically significant (chi 2 = 8.9115, P less than 0.01; chi 2 = 10.9573, P less than 0.01). The incidence of esophageal cancer in the retinamide group after 3 years of medication was reduced by 37.3% as compared with control, while the incidence among patients treated for 5 years dropped by 43.2% relative to control. This difference was statistically significant (chi 2 = 9.2836, P less than 0.01). The incidence of esophageal cancer in the riboflavin group was reduced by 22.2% and 34.8% respectively. The above results indicate that secondary prevention of esophageal cancer is possible and that inhibitory therapy of precancerous lesions of the esophagus is effective in preventing esophageal cancer. This method needs further trial and study in high risk areas of esophageal cancer. The reliability of the experimental results is critically discussed.