对肿瘤原因的探讨,以往习惯于用分析的方法,也就是在严格标准化的实验条件下,测试某单项因子对动物有何致癌效应.这些研究的成果已为肿瘤病因学奠定了深厚的基础.已证实的致癌和促癌因子,以及与其相拮抗的抑制因子种类很多,性质非常多样化,各别在实验性诱癌研究,以及在人类肿瘤流行病学调查分析中,均起一定的作 To investigate the causes of tumors, it has been accustomed to use analytical methods, that is, under strictly standardized experimental conditions, to test the carcinogenic effects of a single factor on animals. The results of these studies have laid a solid foundation for tumor etiology. There are many types of carcinogenic and pro-carcinogenic factors that have been confirmed and antagonists that inhibit them, and their properties are very diversified. Each of them has a certain role in the experimental carcinogenesis research and epidemiological investigation of human tumors.