目前,对可能作为化学预防、化学治疗剂的β-胡萝卜素(BC)正在进行大量研究。流行病学研究表明血清或膳食BC水平与人类肺癌、食管癌与口腔癌发生率之间存在肯定的负相关关系;在几项动物模型研究中发现BC对皮肤、乳腺、唾液腺及口腔憩室等的上皮癌有预防作用,但还未有关于BC对实验性胃肠道癌变作用影响的研究报道。为此作者进行了本实验,旨在研究口服或直肠灌注直接致癌剂N- Currently, a large number of studies are underway on beta-carotene (BC), which may be a chemopreventive and chemotherapeutic agent. Epidemiological studies have shown a positive negative correlation between serum or dietary BC levels and the incidence of human lung cancer, esophageal cancer and oral cancer. In several animal model studies, BC was found to have adverse effects on the skin, breast, salivary gland and oral diverticula Epithelial cancer has a preventive effect, but there is no study on the effect of BC on experimental gastrointestinal carcinogenesis. To this end the author conducted this experiment to study oral or rectal perfusion of direct carcinogens N-