The ultrasound went as well as we could have hoped for. The mass is focused in a three-inch portion of his large intestine but, aside from a single lymph node right next to it, the doctor didn't think it had spread at all.
He's scheduled for surgery on Friday. Needless to say, we could still get bad news when they open him up but we're hopeful. The doctor suspects that we may need to do some drug therapy (chemo) which makes me nervous but... I have a bad history with people and chemo - maybe it's different for cats?
Either way, thanks so much for all your support!