旁观者效应是自杀基因治疗恶性肿瘤的一大特点，它明显地扩大了自杀基因杀伤肿瘤细胞的能力。动物实验结果显示，体内自杀基因的旁观者效应主要与机体的免疫功能有关。如自杀基因疗法与增强机体免疫功能的其它方法结合起来，有望提高杀伤肿瘤细胞的能力 Bystander effect is a major feature of suicide gene therapy for malignant tumors. It significantly expands the ability of suicide genes to kill tumor cells. The results of animal experiments show that the bystander effect of suicide gene in vivo is mainly related to the body’s immune function. Combining suicide gene therapy with other methods that enhance immune function may improve the ability to kill tumor cells.