RESULTS	The mean EGRAC values for the intervention and control groups were 1.452 and 1.606 , respectively ( P < 0.01 ) ; compared with normal mucous membrane of esophagus , the lack of riboflavin increased the risk of esophageal squamous cell carcinoma ( OR = 3.921 , 95 % CI = 1.853 approximately 11.936 ) , but the risk of dysplasia did not increase ( OR = 3.421 , 95 % CI = 0.912-10 .159 ) ; after intervention , the six years average esophageal squamous cell carcinoma incidence of the intervention group ( 112.46 / 100,000 ) was lower than in the control group ( 142.11 / 100,000 ) , although there was no statistical significance ( u = 1.858 , P > 0.05 ) .\