I have taken paxil since shortly after diagnosis. Depression is depression, and causitive factors really don't affect the level of medication.

Ativan is often used with H&N patients during radiation because it is very fast acting, and can be administered prior to being put into the mask.

Talk to your Doctor. They will likely start you out on a lower dose and increase it as needed until you find effective levels. That can take several weeks, but it really does help if you need it
Wayne