"What is weird about prostate cancer is young people with a bunch of testosterone don't get prostate cancer."

I understand the confusion, but it make sense when you think about it. Testosterone doesn't cause prostate cancer; it's just once you have prostate cancer, the cells feed on it.

As we get older and our cells keep dividing, we have more and more chance for mutations to slip in, and sometimes those mutations are cancerous. For some reason, cancerous mutations are especially common in breasts and ovaries for women, and in the prostate and testes for men.

Starving the prostate cancer cells of testosterone can slow them down or stop them completely. We're very lucky there: people with most other types of serious cancer don't have access to such a (relatively) simple treatment option.