Hello there,
Since your good friend is diagnosed with this terrible disease it would be good that you as a support find out something more about his condition. First of all the most common type of kidney cancer is renal cell carcinoma and I presume that this is what your friend is suffering from.
Unfortunately doctors still don’t know what is causing renal cell carcinoma but it is possible that this cancer is diagnosed early so the spreading to the other organs is prevented.
Imaging tests will allow your friend’s doctor to visualize a kidney tumor. The imaging tests which were performed in your friends were probably ultrasound, computerized tomography (known as a CT) or magnetic resonance imaging (known as MRI).
I hope that your friend is going to get better.