Dad (90) has dementia and Non Hodgkins lymphoma. How do we handle this?

He eats what I give him and does a good job of it but he's losing weight. He's lost about 4 lbs in a week and a half. He had this about 7 years ago and went into remission but now it's back and has spread to other areas. At his age and with his dementia, we aren't doing any treatments. Does anyone out there have any dealings like this and how to handle things?

Will only let me select one topic but Dementia and Cancer are the topics.