HI pinkisthenewblac, Chemo is heavy going. Some people are able to work through others not. No one can predict how your body will handle chemo. Radiotherapy I found was far easier than chemo.
Of the group of ladies I attended chemo sessions with, all towards the end could only manage three days a week if that. One was a high school teacher, one a policewoman and another medical researcher.
My advice is see how you go. Your work is important but so is your health. The effects of chemo are cumulative and the same for radiation. You may begin fine and gradually side effects and tiredness increase.
Everyone is different and if you can do it great. The reaction to chemo has nothing to do with your age rather how your body reacts to the chemicals. .Look after yourself I agree the job will wait.