Status and mechanism of controlling precancerous lesions with Chinese materia medica Effects of Coptis chinensis and Evodia rutaecarpa water extracton DMH-induced precancerous lesion of colon Effect of Xiaopiling Granules on Muscular Histochemistryof Gastric Precancerous Changes in Rats Influence of Yiwei Huayu Powder on immune drift in patients with precancerous lesions of gastric cancer