Hi, ClaireBear, and welcome - though I wish I was greeting you under happier circumstances.
Ask your vet about prednisone - this keeps the swelling of the tumours down a bit, and keeps her appetite up. Your vet will know about other things that will keep your girl comfortable.
I don't know if your vet will recommend chemo - if it will help.
There is a product called Transfer Factor that some people have had success with. It basically makes the body alkaline, which cancer can't live in. I don't know what stage your kitty's cancer is at, but again ask your vet and I am sure you will get more responses here.
Do you have a picture of your girl? What is her name?
HUGS to you - I am so sorry you are going through this.
"Remember that children, marriages, and flower gardens reflect the kind of care they get." -- H. Jackson Brown, Jr.