I am so sorry that you and your mom are facing a difficult diagnosis with many complicating factors. I think you absolutely must first have a clear understanding of her kidney function. If she is in late stage kidney failure, this certainly will impact any decision regarding treatment for the cancer.

I highly recommend that you seek out a second opinion from a medical center that uses a team approach (evaluation by medical oncologist, radiation oncologist & surgical oncologist all done in one day) This way all treatment options are considered and presented to you. In addition, these centers treat many oral cancer patients and are highly experienced. There is a list on this site, if you need help finding it, let us know.

The recommended surgery is extensive. The ability to recover from the surgery and quality of life after surgery must certainly be taken into consideration.
Lottie