Arnold jr, thats a good answer.
No study has verified that GH IN REPLACEMENT DOSAGES have caused cancer. It is a theoretical risk though so docs shouldn't give it to patients with cancer. The body has already seen levels of GH that are equivalent to replacement doses. All bets are off with supraphysiologic doses, no one knows.
As Arnold jr said, even though GH causes growth and replacement of tissue, particularly damaged tissue, it also stimulates the immune system, which is our body's survalence system for cancer, toxins, and pathogens.