Hi sadiebabie: Yes it is possible to have stage 4 kidney cancer with the cancer encapsulated in the kidney.
I am a 63 year old female, and I have Chronic Kidney Disease, Stage 4. I had my right kidney removed a year ago because of a rare form of renal cell carcinoma (cancer). My remaining kidney only filters at 19% which is serious. I am on a special diet, low calcium and low potassium because it takes a long time to filter any foods that contain them. Hopefully, I will not need dialysis. I really don't know if I could stand going through that three times a week.
Please feel free to ask any questions you have. Hopefully, I can help you. I've learned a lot since my kidney was diagnosed as cancer.
There are several people on the Kidney disorders board that can offer help. Be sure to ask questions. We are here to help.
Best wishes, Grayfox