If testosterone causes PC then men in their teens and 20s would be the most likely candidates to suffer from it. But PC is almost always a disease of old age .
Not a comment on the parent post, just highlighting that biology is not so straight forward.
But once cancer has occurred, adding more testosterone doesn't matter because the sponge is already super-saturated.
In fact, doctors who have this perspective will permit men with prostate cancer to continue testosterone therapy.
Of course there are many types of cancer so this may not be true for all prostate cancers.