I am just seeking any advice or support from people who have experience with this, I posted previously ( see: ''My 20 year old cat was fine but is suddenly ill and not eating

He has gone into the vets today for an ultrasound and the mass they could feel looks like cancer of the liver, the vet said it is quite unusual, hard in places but pretty much 100% sure is cancer, she didn't want to put him through the FNA biopsy to clarify the exact type as the ultrasound was uncomfortable for him and we did not want him to be sedated for anything. She does not think surgery is indicated due to his age and size of mass, she is going to scan him further to see if it has spread anywhere else. She is also going to look into steroids (some type of chemotherapy) as these can reduce tumours, but she needs to check if they would be ok with his existing meds (phenobarbital and methimazole). She feels that this tumour is quite aggressive.
I am going to pick him up in an hour, has anyone got any experience with this in their cats? I want to know what to expect and what I should be thinking about.
Since last week his appetite has picked back up, he is eating food, toileting normally. To me, he seems to still have a good quality of life, grooming himself, playing with favourite toys on occasion, sunbathing in the garden, enjoying treats and of course lots of cuddles with us, he doesn't seem to be in pain but of course it is so hard to tell in cats

any advice from fellow cat lovers is welcome. x