Having you for a caregiver gives your sister a big "leg up" on fighting this beast. To answer your question, it is the radiation that makes it so difficult to swallow. I didn't have surgery, had rad and chemo. The radiation basically cooks everything in it's path, it's like a microwave oven ( I know that sounds terrible but we do what's necessary to beat cancer) and I had to have a feeding (PEG) tube as I could barely swallow water, so if radiation is decided , get her to eat as much as she can of everything she likes, It may be a while before she can eat anything again. For some it's a couple of months, for me it was 18 months of nothing but Ensure Plus and fruit smoothies. But then, I was 60 years old when all this started. Her youth will, hopefully, wo9rk in her favor as she recovers.