And one could also make the analogy between a toxin and a metal splinter which becomes embedded in the body. Is the virus then drawn to the site of the inflammation and infection and thus a co-factor itself? Certainly the splinter was the initial causal agent. In a very real sense that is what I believe happens. A toxin or other causal agent results in irritation and inflammation which in turn ultimately defeats an impaired immune system and liver and there is a cellular response which becomes the cancer. There is room for a viral role in there somewhere too.