I too have inoperable prostate cancer and have been severely fatigued a year before I was diagnosed. They are telling me that the cancer is not the cause but I continuously tell them they are wrong and are missing something but they don’t listen. At 64 I was in as good shape as when I was 34. I began having extreme lower back pain that was a 10 and my power was gone within two months. No doctor would address the pain and none ever thought about checking my prostate. Over two years I suffered with this until my wife read an article about lower back pain in older men is a sign of prostate cancer. I had to tell them to check it and Gleason nine was found. I explained to them that I suffered major fatigue long before diagnosis but they said that the cancer was not the problem. They also said the pain was not caused by the cancer either and still refuse to address any of it. I have walked away from the health care system and take care of myself in any manner I have to. When they will not listen they leave you no choice but to walk away. Don’t let them tell you that your fatigue is not cancer related. It is! You are correct. It is them who are missing something. In my case they would not listen. Hopefully in your case they will. Best wishes