关于遗传因素在致癌中的作用多年来一直存在着争论。尽管根据C_3H和C_(57)BL纯系小鼠推测遗传因素可能起了重要作用,但是有关其对人类群体作用的直接证据却尚未见报道。然而对于某些类型的癌症来说,病人常常具有恶性肿瘤的阳性家族史。例如,据报道,在中国一组452例原发性肝癌病人中,有23％具有大多为肝癌的癌症阳性家族史。在一组244例鼻咽癌 The role of genetic factors in carcinogenesis has been debated for many years. Although genetic factors may play an important role based on C_3H and C_(57)BL pure strain mice, direct evidence on its role in the human population has not yet been reported. However, for certain types of cancer, patients often have a positive family history of malignancy. For example, it is reported that 23% of a group of 452 patients with primary liver cancer in China have a positive family history of cancer, mostly liver cancer. A group of 244 cases of nasopharyngeal carcinoma