It's not over until it's over.
The problem with liver surgery in this stage is that disrupting the cancerous area can cause it to spread significantly more rapidly than in non-invasive conditions. This can cause further metastasizing which is ALWAYS a bad thing.
Despite the pain, suffering, and other awful conditioning brought about by this- Biscuit is likely going to be around for far longer than predicted. I sure do hope they cure him before it's too late.
Best wishes to he and everyone else who has won the most undesired of lotteries.