Feeding a cat with cancer

My 19-year-old cat has a cancerous tumor below his tongue. We know his time is short but he's not ready to go yet. He still has energy and an appetite but it's painful for him to swallow. We're interesting in finding out what liquid or near liquid food, like soup or broth, is safe and nutritious.

I had a very old Siamese with that condition.  I made him a few combinations.  One was just standard chicken soup, made by boiling chicken & chicken bones and then after it cooled, removing the jelly like clear broth which was high protein, reheating it into broth,and then mixing in with some powdered KMR kitten formula to give him vitamins etc.  We also had him on liquid pain medicine and would give him that about an hour before giving him food -- low doses tough as too much can make them nauseous.  It's a trial and error thing.  Very sorry about your old guy, but look what a long and loved life he has had.