Patrick Swayze and Barbara Walters

A year after he was diagnosed with pancreatic cancer, Patrick Swayze admits he has been "going through hell."

The actor opened up about his cancer battle with Barbara Walters in his first interview since the diagnosis, set to air Wednesday (10 pm/ET, ABC). "I've never been one to run from a challenge," he told her.

When Walters asked him if he was scared, he said, "I don't know. I will be so either truthful or stupid as to say no. But then... when I say that, I have to say yes, I am."

Swayze continued working during his treatment, staying in front of the camera to star in A&E's new FBI drama, The Beast, to premiere Jan. 15.

Yet, he knows that his cancer battle may not be over. "You can bet that I'm going through hell," Swayze said. "And I've only seen the beginning of it."