I have personally known two people with kidney cancer. The first is my father. One tumor, about the size of a golf ball. My parents researched it on their own and due to a generalized decrease in kidney function, they did not want for him to lose the whole kidney. The fourth consult finally agreed to remove only the tumor, and not the whole kidney. It went well, but the doctor did not get clean margins. (The goal is to take a little healthy tissue all the way around so you know that the whole tumor was taken out.)
Years later, Daddy had symptoms again. Those little bits that were left had grown and this time they really could NOT do surgery. So an out of town doctor ... VERY specialized ... came in and used a long needle and an ultrasound or CT or something to see what he was doing. He injected radioactive poison into the center of the tumor and then they waited to see if it worked. The poison ate out the tumor and Daddy got well.
A couple of years later, they had to do it again. Daddy got well again.
Now, my father is 83. I am under the impression that he is no longer a candidate for that sort of intervention. But ... the tumor is not such a threat anymore.
Bottom Line: It doesn't have to be perfect to have a happy ending.
The other person with kidney cancer had that kidney removed and he got well. Big surgery, great result. He's about 50 now, and doing great!
But this was supposed to be about YOU and YOUR DAD, not people I know. So, you, Deep, pray. Pray with your heart and then trust God to have a plan that is for the best. Maybe there's someone who needs this threat in order to fully submit to God. Maybe seeing your family genuinely trust God in a bad situation will bring them to Christ. Maybe God is allowing this to happen so He can miraculously heal your father, and then be praised for it.
Know that God has this in hand, and the scary parts are not the important parts.
I will be praying for you and your family.