Pauwels Ernest K J, Erba Paola A, Kostkiewicz Magdalena
Leiden University Medical Center, Leiden, The Netherlands.
Drug News Perspect. 2007 Nov;20(9):579-85. doi: 10.1358/dnp.2007.20.9.1162242.
The production of oxidative species (free radicals) is very common in many types of cancer cells. This oxidative stress has been associated with the carcinogenic process as it can damage cellular proteins and lipids and form DNA adducts. Antioxidants interact with these oxidative species and reduce their (pro)neoplastic activity. Therefore, intake of antioxidants has been hypothesized to interfere with carcinogenesis. Chemoprevention by dietary or supplemental antioxidants is a strategy which aims at reducing the incidence and prevalence of cancer. Antioxidants are present in plant food and considerable knowledge has been obtained on the mechanisms by which these phytochemicals interact with the carcinogenic process. In general, antioxidants prevent oxidative species to reach a sufficient intracellular level to promote carcinogenesis. However, oxidative species do not only have a detrimental effect. At physiological levels they also confer prevention by inducing immunoresponses and apoptosis in order to remove the damaged cells. These beneficial actions are of extreme value for normal organ function, and it casts doubt on the use of supplemental antioxidants. Indeed, from recent high-quality epidemiological studies the image emerges that supplemental antioxidants may help to prevent cancer only in diet-deficient populations or individuals. This paper aims at providing an overview on the knowledge about the most common (dietary) antineoplastic chemoprevention agents and the clinical results obtained from epidemiological studies in this field.
氧化物质（自由基）的产生在许多类型的癌细胞中非常普遍。这种氧化应激与致癌过程有关，因为它会损害细胞蛋白质和脂质并形成DNA加合物。抗氧化剂与这些氧化物质相互作用并降低其（促）肿瘤活性。因此，有人推测摄入抗氧化剂会干扰致癌作用。通过饮食或补充抗氧化剂进行化学预防是一种旨在降低癌症发病率和患病率的策略。抗氧化剂存在于植物性食物中，并且已经获得了关于这些植物化学物质与致癌过程相互作用机制的大量知识。一般来说，抗氧化剂可防止氧化物质达到足以促进致癌作用的细胞内水平。然而，氧化物质不仅有有害作用。在生理水平上，它们还通过诱导免疫反应和细胞凋亡来实现预防，以清除受损细胞。这些有益作用对于正常器官功能具有极其重要的价值，这也让人对补充抗氧化剂的使用产生怀疑。事实上，从最近高质量的流行病学研究中可以看出，补充抗氧化剂可能仅对饮食缺乏的人群或个体预防癌症有帮助。本文旨在概述有关最常见（饮食）抗肿瘤化学预防剂的知识以及该领域流行病学研究的临床结果。
