Stephany, the standard explanation is that the chemo makes the cells more receptive to the radiation. I opted for this, figuring I wanted all available treatments. Side effects depend on the person and the chemotherapy drugs used. When you find out what chemo she will have, we can better tell you what to expect, although the chemo nurses are wonderful about that. I had five chemo treatments and it was not terrible at all. My advice is to take advantage of everything that is offered.
Joanna
P.S. It apparently works, at least some of the time, because i feel like a million dollars and have since treatment finished. I wish the same for your mom.