类胡萝卜素是天然脂溶性色素，它为植物和动物提供绚丽的色彩。饮食中摄入类胡萝卜素可以降低各种癌症发生的风险。临床前的研究表明，一些类胡萝卜素在体外及体内具有很好的抗肿瘤效果，预示着这类化合物在肿瘤防治中的重要作用。由于化学预防是控制癌症发生的最重要的措施之一，所以研究利用类胡萝卜素化学防治癌症的分子机制非常诱人。尽管高剂量β-胡萝卜素在临床试验中并没有表现出化学预防活性，但是各种类胡萝卜素，例如β-胡萝卜素，α-胡萝卜素，番茄红素，叶黄素，玉米黄质，β-隐黄质，岩藻黄质，角黄素和虾青素，已被证明在某些组织中具有抗癌活性。本文综述了利用类胡萝卜素防治癌症并讨论了可能存在的机制。

Cancer chemoprevention by carotenoids

  Carotenoids are natural fat-soluble pigments that provide bright coloration to plants and animals. Dietary intake of carotenoids is inversely associated with the risk of a variety of cancers in different tissues. Preclinical studies have shown that some carotenoids have potent antitumor effects both in vitro and in vivo, suggesting potential preventive and/or therapeutic roles for the compounds. Since chemoprevention is one of the most important strategies in the control of cancer development, molecular mechanism-based cancer chemoprevention using carotenoids seems to be an attractive approach. Various carotenoids, such as β-carotene, a-carotene, lycopene, lutein, zeaxanthin, β-cryptoxanthin, fucoxanthin, canthaxanthin and astaxanthin, have been proven to have anti-carcinogenic activity in several tissues, although high doses of β-carotene failed to exhibit chemopreventive activity in clinical trials. In this review, cancer prevention using carotenoids are reviewed and the possible mechanisms of action are described.