It comes days after he posted on social media about dying.
"You start a new life."
Willis and Moore divorced more than 20 years ago but still remain close.
"It's hard on the person diagnosed."
The '35' writer said it "felt like the worst indigestion pain ever".
"The idea that I won't be able to remember the life I experienced, or my wife, my kids, is probably my biggest fear."
"I've seen young guys turn up with tumours the size of American footballs sitting in there."
It's Men's Health Week and it's a time to check in with yourself and make sure you're still running at full capacity.
