Did this trade save his life?
Potentially yes. But I think he would have gone through thorough physical within the next few years so they would catch it then.
So the difference between him surviving depending on when they catch it is probably :
99% chance of living cancer free - catch it early (now with this trade) maybe stage 1 cancer...
95% catch it in 2023 stage 2 ...
13% catch it in 2028 or 2030 etc stage 4...
From talking to my friend that had his kidney removed it is something like this but my stats are not to be trusted.