@rose I'm sorry to hear you're struggling with this issue. I had 20 doses of rads and was lucky enough to be able to take time off work while I was going through all the treatments and surgeries. But yes, when I did start trying to enter the work place again, it was a real struggle to concentrate - still is. I was able to come back on a graduated plan - 4 hrs a day for 3 days a week and build up from there. All that kept going through my mind was "I have cancer...don't you people understand??" and I wanted to tell everyone which wasn't appropriate.
Do you have any capacity to be able to work from home, even if it's just one day a week? At least then you can lie down and rest on and off during the day and give your mind and body a break.
I don't know how the academic world works but is there a HR rep or Union rep that you could talk to about a work/life balance? And try and adjust expectations on what you are capable of at the moment? Set up some kind of plan about what is realistic to achieve in a day/week while you are recovering from treatment? Best of luck to you.