Swayze wanted to keep the secret as long as possible while he and his wife decided how to proceed, but the news of his life-threatening illness broke early last year when tabloids reported he had only five weeks to live.
Swayze said he was able to ignore the tabloids in the past but began to feel differently "when they start screwing with people I love, when they start screwing with my family.
"Hope is a very, very fragile thing in anyone's life," he said, "and the people I love do not need to have that hope robbed from them, when it's unjustified and it's untrue."
Swayze categorically denied tabloid reports that the end is near. "Am I dying? Am I giving up? Am I on my deathbed? Am I saying goodbye to people? No way."
Dr. John Chabot, one of the country's leading pancreatic cancer researchers at New York-Presbyterian Hospital/The University Hospital of Columbia and Cornel, calls pancreatic cancer the silent killer because there are often few, if any, symptoms.
While Chabot said it's difficult to know what causes one individual's pancreatic cancer, he said that "smoking is the one thing that we know of that clearly, clearly, clearly increases the chance that somebody's gonna get pancreatic cancer."
Swayze has been a smoker for decades. He admitted to Walters that despite his diagnosis, "I am not a nonsmoker. I've seriously cut down." When pressed, he acknowledged, "I will go so far as to say probably smoking had something to do with my pancreatic cancer."
He said he hasn't quit yet because he does not believe it will change his prognosis. But he vows, "When it looks like I may live longer than five minutes? I'll drop cigarettes like a hot potato." For now, he said, "it's not my priority."
Swayze, who plays an FBI agent, was proud to say that "nobody on the set ever saw me whine, moan like a girly-loser-man. I would do an attitude adjustment every morning."
"I've always known that Patrick is a really tough guy, but until all this illness came up in this past year, I had no idea really, the depths of his toughness and, and the amount of fight in him," said Niemi.
Still, at one point he considered giving in. "By the third episode in, at one point I didn't know if I was gonna finish this thing and I thought I'd made a big mistake," he said. "It just made me angry at myself though."
No matter how bad he felt, Swayze said he refused to take painkilling medicine. "If it's about pain, I can deal with it. I, I can rage my way through it. When you're shooting, you can't do drugs," he told Walters. "I can't do Hydrocodone or Vicodin or these kinds of things that take the edge off it, 'cause it takes the edge off your brain."
In five months, Swayze missed 1½ days of work.
Through it all, Niemi was by his side, during the private hours of excruciating pain and on the set, always supporting his decision to continue the work he loves. She even directed him in an episode.
She said it was Swayze's decision to commit to the series, but "the moment he showed up in Chicago there was this enormous burst of energy that was stunning. And that kind of said, you know, maybe we are in the right place."