Olfactory neuroblastnoma

My son is 52. He was diagnosed with olfactory neuroblatnoma in May 2016 And had an operation to remove the tumor through the nasal cavity. We knew it was serious but when he came home afterward he was really well and confident about the future. He started radio therapy 3 weeks later and even after 4 of the 6 weeks of the daily treatment he was fine. From that time he has just gone downhill. He is not ill but so very low and so tired he can hardly do more than work a few hours, eat with a lot of encouragement, and sleep. 

I wondered how other patients are coping after their treatment.

Maggii