I have had ED to some extent for some (5-6?) years so well before my recent diagnosis. I was put on Testosterone gel and I was on that for about 3 years. Then my PSA suddenly went up. So, ED caused by PCa? I would say so, and of course, the worst treatment for PCa is testosterone.
My GP "doubted" that PCa was the cause of ED but I would disagree with him.
Anyway, since I am on "Active Surveillance" I won't know if my ED is cured by any treatment for the PCa, but I very much doubt it.
I currently have one GP prescribing Cialis and one who said no! The one who said no said "they cost £7.50 each" I will go and see the other GP soon, that should be interesting!
John