We're exposed to things that might cause cancer where weren't exposed to them before and so that might be a reason.

我们暴露于可能致癌的物质中,这些物质在以前是没有的,这可能就是原因之一

耶鲁公开课 - 生物医学工程探索课程节选

One way that that's done is by introducing genes into cancer cells, genes that aren't normally expressed in any mammalian cell, but that will cause the cancer cell to die.

已经成功应用的一种方法是,将基因导入癌细胞,而这种基因通常不在哺乳动物细胞中表达,但是可以导致癌细胞的死亡

耶鲁公开课 - 生物医学工程探索课程节选