In a two-part Early Show interview with anchor Bryant Gumbel, King called it "a big, scary nasty book...It's a mean book in a lot of ways."
The book originally was called Cancer and its "bad guys" are parasites that attack the gastrointestinal track. In choosing the subject matter, King said, he searched for something that was still taboo.
"We're the generation that talked about everything," King said, so he asked himself about what door is still closed.
The answer: The door to the bathroom, which is where, King points out, the seven early warning signs of cancer are usually detected.
In his book, King rewards true followers by dropping references from his other novels into this book. For instance, telepathy (in Carrie and other novels) plays a key role. Snow, which appears in many of his works, is present in many critical scenes.
He also draws on a variety of sources - from Joseph Conrad's Heart of Darkness, to
the TV series The X-Files and the film Alien.
King has written more than 30 bestsellers, but this one he wrote entirely in longhand using a fountain pen.
"It slows you down," the author said. "It makes you think about each work as you write it down."
Among his works, many of which have served as the basis for feature films, are On Writing, Hearts in Atlantis, The Girl Who Loved Tom Gordon, Bag of Bones and The Green Mile.
King, who lives in Maine with his wife Tabitha, also a novelist, is a member of the Rock Bottom Remainders, a rock band comprised of authors. Other sometime members include Amy Tan, Dave Barry, Mitch Albom and Warren Zevon.
Hit by a truck as he was walking near his home one night, King suffered life-threatening injuries. He says he doesn't remember the point of impact, but does remember seeing the car coming at him and later awakening in a ditch with a man, whom he later learned was the truck's driver, standing over him.
He has recovered from the accident, although he still suffers from some residual pain.
"I'm the happiest guy in the universe," he told Gumbel.