There are lots of flora changes in the mouth of someone that is going through treatment, and it is also hard for them to keep their mouths really clean because of the discomfort in doing so. That some of them have bad breath isn't really a surprise. But having stated that, it is a good idea that the docs, or the dentist involved take a good look around to be sure there are no other contributing things like an abscess or something else. In my own case the most painful thing was to keep my tongue clean (I brush it now) because of all the mucocitis sores on it, and it is a great place for foul smelling bacteria to collect in between all those papilla.

Brian, stage 4 oral cancer survivor. OCF Founder and Director. The first responsibility of a leader is to define reality. The last is to say thank you. In between, the leader is a servant.