不同人群倾向于罹患不同的癌症。第三世界国家居民多发肝癌,西方国家居民好发乳腺癌和结肠癌,日本人则高发胃癌。一些国家癌症发病率一代一代发生改变,而移民却倾向于罹患新定居国家的特殊好发癌症,这可能是由于饮食、生活习惯和环境因素不同所造成的。此外,皮肤癌和肺癌与单一因素(日晒和吸烟)有关,而其他一些常见癌症的病因则不甚清楚。当代核酸化学技术的发展,已能分辨癌细胞及与其对应之正常细胞在核酸顺序和基因表达上的区别。从这一点出发,也许能够阐明肿瘤发生过程的各个步骤。本综述旨在分析事实资料,并对人类癌症分子生物学问题作某些推论。实验致癌作用有许多方法能在实验动物中诱发癌瘤。将动物作为靶体暴露于可损害DNA 的物理或化学因子中使之 Different people tend to have different cancers. Residents of third-world countries have multiple liver cancers. Residents in Western countries have good breast and colon cancer. Japanese people have high incidence of gastric cancer. In some countries, the incidence of cancer has changed from generation to generation, while immigrants have tended to suffer from particularly prevalent cancers in newly established countries. This may be due to differences in diet, lifestyle, and environmental factors. In addition, skin cancer and lung cancer are associated with a single factor (sun and smoking), while the causes of other common cancers are unclear. The development of contemporary nucleic acid chemistry has enabled the discrimination between nucleic acid sequences and gene expression in cancer cells and their corresponding normal cells. From this point of view, it may be possible to elucidate the various steps in the process of tumorigenesis. This review aims to analyze factual data and make some inferences about the molecular biology of human cancer. Experimental carcinogenesis There are many ways to induce cancer in experimental animals. Exposing an animal as a target to a physical or chemical agent that can damage DNA