I also had adjunctive chemo, initially cisplating and then carboplatin. Used this way the chemo is a radiosensitizer as Gary already said.
I had this weekly (a total of 7 times) and at least in my case the effects of the chemo were not an issue, although I did end up with a low white cell blood count (from carboplatin). .... For which they have another injection (neupogen not a big deal).
Markus