Looking for advice: 45 point drop in eGFR

Multiple series of urine tests. All show blood. I have a ginormous staghorn calculus (2+ inches X 1+ inches) . EGFR subsequently dropped 45 pts.
In my demographic, the bleeding w/o infection/bacteria has a high risk of urologic cancer (30%).
Recent test show enlarged external iliac node ( w/o a know infection /cause - a red flag for possible urologic/gynecologic cancer. If the staghorn is responsible for that kidney failing, will they need to remove the whole kidney? If just the calculus is removed, and if that Kidney is only functioning at 5% , will it likely recover more function?