My beloved kitty, who is 14 (wow, it's hard to believe I adopted her that long ago!), has cancer. She's had one tumor removed years ago. It's returned, but it's not progressing quickly, and she's still happy and healthy. She purrs if you so much as look at her.
But it's good that you had the surgery even if it cost $400 and he's a bit uncomfortable! If it hadn't been a fatty tumor, and you'd put it off, it could've been really bad. Never regret taking good care of your pets! They deserve it.
And I'm so glad she doesn't have cancer.