Like everyone is saying, everyone reacts differently, but I was unable to work from a week before my surger, until 7 months later due to complications from radiation and peg tube, and infections.
Everyone is different.
Also, after those 7 months, I went back to work. But the thing that sucks with this is you aren't deemed in "remission" or "cured" until you have had 5 years of clear scans. So hopefully you won't have to be in "remission" to go back to work, but just cancer free!
Best of luck!