My colon cancer spread to liver. i have to see a nephrologist due to kidney damage. if organ damage prevents future treatment, what's approx lifespan?

First things first: Let's take one step at a time. Whether or not there is kidney damage, and to what extent, may not dictate the next step in treatment. After seeing the nephrologist, sit down with the oncologists and a surgeon to determine the next step to take. Easy for me to say, I know. This is probably pretty scary right now. Try to take it one step at a time.

Depends: It highly depends on the type of cancer, spread to other organs, your overall functional status and comorbidities that you suffer from. Hope it helps.