Alex Trebek Undergoing Chemotherapy Again After "Numbers Went Sky-High"

The 'Jeopardy!' host — who is battling stage 4 pancreatic cancer — opened up about his latest health setback during a Tuesday interview on 'Good Morning America.'

Alex Trebek is undergoing chemotherapy again. During an interview that aired Tuesday on Good Morning America, the Jeopardy! host — who is battling stage 4 pancreatic cancer — opened up about his latest health setback.

"I was doing so well. And my numbers went down to the equivalent of a normal human being who does not have pancreatic cancer. So we were all very optimistic. And they said, 'Good, we're gonna stop chemo, we'll start you on immunotherapy,'" Trebek told ABC News' T.J. Holmes, before explaining, "I lost about 12 pounds in a week. And my numbers went sky-high, much higher than they were when I was first diagnosed."

Added the TV personality, "So, the doctors have decided that I have to undergo chemo again and that's what I'm doing."

Trebek went on to describe how cancer sometimes causes him "excruciating pain" and "fatigue," while also saying, "Cancer is mysterious in more ways than one." He also said that his diagnosis, which he first revealed in March, has caused him to, at times, feel "depression" and a "surge of sadness."

"When it happened early on I was down on myself. I didn’t realize how fallible each of us is in his or her own way…I talk to the audience sometimes and I get teary-eyed for no reason," he said on GMA. "I don’t even bother to explain it anymore, I just experience it. I know it's a part of who I am and I just keep going."

Asked how he feels about his mortality, Trebek insisted that he isn't scared of death. "I realize that there is an end in sight for me, just as there is for everyone else. One line that I have used with our staff in recent weeks and months is that when I do pass on, one thing they will not say at my funeral is, 'Oh, he was taken from us too soon,'" he said. "Hey guys. I’m 79 years old. I’ve had one hell of a good life. And I’ve enjoyed it…the thought of passing on doesn't frighten me, it doesn't. Other things do, the affect it will have on my loved ones…it makes me sad. But the thought of myself moving on, hey folks, it comes with the territory."

Trebek is currently taping episodes for Jeopardy!'s 36th season, which premiered Sept. 9. Watch his GMA interview below.