I went back to work after 3 months 6 hours the first several weeks and then 8 hours for a month. Then finally on my 9 hours days. I did get very tired, so worked, ate and sleep seemed like all I got done at times. My memory was slow at first I had to ask questions which made me laugh (when I needed it), because I was and again the one everyone goes to for answers. I was very lucky I had two great bosses (new ones are good also), they were on a different floor but several times a week would come down you are not pushing yourself to hard (they know me). The one thing I had hard time at work was things got to me easier and I would have to get away. Now 4 years later work is back to normal.
I had a relapse after 2 years because it started growing back and then had a week of radiation, and was drain for months from that, which getting up at 0330 did not help either, that is my life since I now got on a van pool to go to work, I can sleep if I want on the hour commute (which I feel is safer in DC traffic with one eye). It days like now I have to tell myself take it one day at a time and not get upset. I have to take AL because the van drivers decided where they are coming from they have 2 inches of snow (which to me being raised in central PA is nothing!) is not going, so either I take leave or drive in which being dark yet and wet, snow, freezing rain and this area traffic and crazy drivers I do not trust myself which I cried hate to lose my AL leave this way but safer then sorry. Good luck to you.