Hi Jay-Cee,
This issue is really complex. Firstly, most folks who I've spoken to about this had Squamous Cell Carcinoma (SCC) of the mouth, not melanoma.
Secondly, there's different intensities of radiation, and different places which they direct it at. In my case (oral SCC), the side effects were extreme at the time, and took a long time to recover from (3-6 months), but I stress that this is not everyone's experience. Personally, ulcers throughout my mouth made pain a major, major issue. Unlike your dad and many others, I did not have any kind of feeding tube. BUT, I was 43 at the time, and hence my recovery and quality of life afterwards has seriously surprised the doctors. Once again, others have not had this recovery experience.
So...my advice is to book an appointment with the radiation oncologist. Write down all your questions, and get them all answered to your satisfaction. If you still have questions, then pursue the issues once again. You and your dad must have answers, to make an informed decision.
Such as:
1. Prognosis with radiation.
2. Prognosis without radiation.
3. Quality of life post-treatment.
4. Side-effects during treatment.
5. Permanent side-effects.
6. Process of administering treatment - is painless, but can be traumatic for some, esp. those who may suffer claustrophobia or similar.
Product recommendations (subject to clinician approval, of course): Peter Macallum Cancer Centre in Melbourne make a mouth wash under their own brand. Marvellous stuff.
If and when oral intake is needed, Nutricia make Fortisip protein drinks which taste good, and did not aggravate my ulcers. Must be factory-mixed. Self-mixed powder products STUNG my ulcerations because of undissolved particles.
All the best to you and your father on this difficult journey. Don't hesitate to ask if I can be of further assistance.
Regards,
Mark.