I had lesion on my left kidney diagnosed as malignant a year and a half ago. Because of my age I opted out of a total nephrectomy and instead have had Keytruda immunotherapy. The lesion I have is much smaller than yours at 12 x 11 mm per last CT scan two months ago; it has actually reduced in size from the initial scan over a year ago. The only suggestion I can give is to fully discuss all options with doctor including what possible side effects from therapies and what to expect after surgery. The more information you get the better in making decision of what path to take.