In the 1990s, patients with complete immune system collapse primarily developed viral cancers, but not typically lung or pancreatic cancers.

“one line of evidence was that in patients with the complete collapse of the immune system such as patients with HIV or complete collapse of at least of one wing of the immune system they would get these cancers you've nobody else could get but what's interesting about them and this is where the thought experiment this is with the brain cells start sort of ticking and wandering they would typically get viral cancers viruses that would now get unleashed we now know many of them viruses like human papilloma virus they would get cervical cancers they would get anal cancers so a lot of viral cancers but patients with HIV did not generally get lung cancer”