Castration

My brother is 58 years old. He has been diagnosed with inoperable prostrate cancer. The doctor has told him that he couldn`t afford the hormone treatment, so he wants to castrate him The doctor however hasn`t offered much hope with that either. My brother has the idea that he has a couple of years left.Now he knows the loss of his testicles will cause him to lose muscle mass ans thus weakness. I would like to know if anyone has an idea as to how long it takes to lose so much muscle mass that you can`t function. My brother is very active, and I thought he might die before he lost so much mass that it would render him unable to ride a bike.