So, according to some science fiction theorists, the way that xenomorphs are produced is that when the facehuggers attach to you they inject you with a form of tumor that starts growing inside of you and taking parts from you. What if cancer was like that? But that would have to rely on the fact that that happened to humans already. IT DOES. It's called Teratoma. It's when tumors form teeth, hair, and bones. So what if cancer is us trying to regenerate?