Alicia,
Boost VHC, which you can order via Amazon giving credit to the OCF, has 560 cals in the same small can as Ensure so by drinking the same number of cans he can perhaps double his caloric intake.
Did they test his cells for
HPV? Was he a tobacco user?
He can also get a nasal tube (no surgery, just a 3 minute feeding the tube down the nose into the stomach) and that can GREATLY help you and him get tons of calories and water into him painlessly. I had one for 2 weeks and it was a godsend.
Listen don't worry about anything else right now other than completing his Tx and getting past the few weeks post Tx which are usually the worse weeks for all of us. After that, we call it walking out of the tunnel, his and your recovery will start.