You didn’t say where your Dad’s cancer is, so I am making the assumption that his mouth will be radiated. In this case, it would be a good idea to get him a Waterpik which will help get rid of the stringy saliva during radiation. He will get a fluoride tray from his dentist and will have to use it all through radiation to minimize damage to the enamel. So, it is a very good idea to get him the prescription for Prevident 5000. In fact, it would be good for him to continue to use it even after radiation. It will help preserve his teeth. A lot of patients get tooth decay and need fillings or root canals after radiation. The toothpaste should help. He will also need some moisturizer like Lubriderm for his skin (to be applied after radiation, and NEVER before radiation). There will be other things he might need, depending on what happens. That can wait a bit. These, from right off the top of my head, are things he should have ready.