Swayze said that in the year since his diagnosis, he had defied the statistics and "trash magazines" that predicted he should have "already been dead a long time," but he acknowledged that time may be running out.
"I'd say five years is pretty wishful thinking," he told Walters. "Two years seems likely if you're going to believe statistics. I want to last until they find a cure, which means I'd better get a fire under it."
The 56-year-old actor said he's waging his battle against cancer "moment to moment."
"When do you decide the fight isn't matching up to your quality of life?" he asked. "So far, I've got potential for a lot of quality of life."
Swayze responded well to his first round of chemotherapy, but as is common, that treatment eventually became less effective, so he recently began a new therapy.
"You can bet that I'm going through hell," Swayze said, but he vowed to keep fighting.
"I'm at the beginning of my battle. And I expect it to be a long hard battle, one that I'm gonna win according to certain rules … the rules that the cancer isn't going away. Now, mind you, I keep my heart and my soul and my spirit open to miracles. I pray."
Asked if he was scared, Swayze told Walters, "I don't know. I will be so either truthful or stupid as to say no. But then I immediately, when I say that, I have to say yes, I am."
Swayze's battle with cancer began late in 2007. As he celebrated New Year's Eve with his wife, Lisa Niemi, Swayze felt that something was wrong.
"I tried to have champagne, and it would be like pouring acid, you know, on an open wound."
And soon it got worse.
"My indigestion issues got gigantic and constant. And then I started thinking, 'I'm getting skinny. I dropped about 20 pounds in the blink of an eye.' And then when you see it in the mirror, when all of a sudden you pull your eyes down and the bottom of your eyes go yellow and jaundice sets in -- then you know something's wrong."
Swayze realized that he needed medical attention. "I started doing a little research and started realizing this is not pretty. This is not a good thing."
- WATCH: Swayze Speaks Out About His Cancer
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Patrick Swayze: 'Am I Giving Up? No Way'
Doctors found that the actor had a malignant tumor in his midsection, and a tiny mass on his liver. Pancreatic cancer is extremely difficult to diagnose, and only after a battery of procedures over several days were his doctors able to make a definitive diagnosis: stage 4 pancreatic cancer.
It fell to Niemi, 52, to break the news to her husband.
"It was very surreal," she said. "They were like 99 percent sure. And I know he was still a little dopey from the procedure and I could have told him then, and I said you know what, this is information he can do without for just a few hours, 'cause after he learns this, we can't go back. So I waited until the next morning to tell him about it, and for the first few weeks it was like being in a nightmare you couldn't wake up from."
Although the majority of patients with advanced stage pancreatic cancer die within six months of the diagnosis, Swayze reacted with defiance.
"I have the meanness and the passion to say, 'To hell with you. Watch me! You watch what I pull off.'"
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 Takes on 'The Beast'
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."
The couple met 36 years ago, when 16-year-old Niemi walked into his mother's dance studio in Houston, and the 20-year-old Swayze became smitten for life.
Married for 33 years, Swayze said of his wife, "I have no greater respect for any other human being on this earth like I have for her. Part of me says I couldn't have made it through without her, but, of course, the other part of me says I could have, but not nearly as elegantly as I have."
'I Can Keep Going'
Swayze insists he doesn't want to be the poster boy for living with cancer, but like it or not, his stubborn refusal to let cancer alter his life has become an inspiration. He has received thousands of letters from around the world offering advice and encouragement.
"The outpouring of love has, has constantly astounded me," Swayze said.
Swayze said the illness has made him think more about the afterlife.
"I don't know what's on the other side," he said. "It tests everything I believe in … that here is something unique in all of us that does not, does not die."
Swayze said he talks to his father, who died before the actor became famous.
"I like to believe that I've got a lot of guardian warriors sitting on my shoulder, including my dad, saying, 'You just let Swayze dog know it's been his turn all this time. You just let us do the work and we'll finish it for him.' And so, I'm trying to shut up and let my angels speak to me and, and tell me what I'm supposed to do."
"What winning is to me is not giving up, is no matter what's thrown at me, I can take it," Swayze said. "And I can keep going."
For more information about pancreatic cancer, visit:
The Pancreas Center at Columbia University Medical Center
The National Cancer Institute's Pancreas Site