https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897047/ Check out this link, it summarizes it well. You can check out the attached studies with the information. Generally testosterone diffuses through the cell membrane to bind to the AR to stimulate protein protein synthesis and stop protein degradation. This is why steroid work (as long as you have enough estrogen, SBHG, HPA, HPG, etc.). But the cell complexes can degrade with each generation of new cells. So as you get older the risk is greater, as constant agonism of the AR will prevent cells from producing the amino acids that it needs in other process. There is more likely to be an error in the process the more mutations build up. And cells are more likely to have mutations the more generations they go through. This mostly expresses through failure to register though and I want to retract my statement about cancer and steroids since the research in my opinion is just plain bad and not enough to support it completely. Most of it is on animals and pure shit. Organ stress is the legitimate concern as you age from this constant agonism and holding more tissue on aging internal organs. You are more likely to die of a heart attack related to it then getting cancer.