When my son was in the IMRT treatment phase, he was given a week long break after about two and a half weeks because of open painful sores in his mouth, and again later on a slightly longer break because of Christmas shut down of the Radiation office where everyone had a short break. In talking to other patients while waiting for him I found out there were other patients who had to have a "break" from treatment. To be sure regarding your own treatment, it may be a good idea to check with your doctor and ask him about any effects of the interruption in treatment.