I'm so sorry to hear that. I get so worried if my parents get the slightest headache, so I can't imagine how you must be feeling. I hope it was caught early, and that it hasn't spread past the kidney. If its only in the kidney, hopefully they can remove the tumor, or hopefully not, but if neccessary, they can remove one kidney. Many people live with one kidney and in some parts of the world where many people are ill and need to remove both of their kidneys, people often donate one of their kidney and they live just fine on one. I wish your dad the best of health and hope he'll come through this and be the happy and healthy daddy he always was. Please keep us updated.