My uncle had all the classic symptoms of a kidney tumor for several months before he went to see a doctor about it.
He had back pain, increased blood pressure and unexplained weight loss and fatigue. They found a tumor on his kidney, but because of the location did not want to biopsy it right away.
What they did discover was that his kidney functions were extremely low. He had to begin dialysis treatments. He did feel like he had a little bit more energy after starting the treatments, but they can take a toll on you as well.