Well, I don't know all the facts. So, understand that, however, apparently a Doctor on his reddit channel, wrote a blurb about what he knew/understood about the situation from the few facts we have (while he was on a lunch break). Under normal circumstances, cancer doesn't just spread to the liver from the bowel, without being in the blood stream first. And that's bad, because among other things it means just getting a liver transplant doesn't get rid of what's in his blood. And as I said above, the Doc also suggested that it's likely he has lesions on other vital organs (heart/lungs), that're simply too small for the CT to see.
Thanks for explaining it.
Man i really hope they find a cure for this thing someday.