"Jeopardy!" host Alex Trebek is heading back for another round of chemotherapy after losing a large amount of weight and having his numbers rise sharply, he told ABC's "Good Morning America" on Tuesday.
The news is a setback for the beloved game show host, who's been battling stage 4 pancreatic cancer this year.
In late August, Trebek seemed to be doing exceedingly well after a long round of chemotherapy, and he returned to taping the 35th season of "Jeopardy!".
But a change in his condition now means that Trebek, who turned 79 in July, is headed back for more chemotherapy.
"I was doing so well. And my numbers went down to the equivalent of a normal human being who does not have pancreatic cancer," Trebek told "GMA." "So, we were all very optimistic. And they said, 'Good, we're gonna stop chemo, we'll start you on immunotherapy.'"
However, more recently, ""I lost about 12 pounds in a week," Trebek said, "and my numbers went sky high, much higher than they were when I was first diagnosed. So, the doctors have decided that I have to undergo chemo again and that's what I'm doing."
His journey with cancer hasn't always been easy, he added. Physicially, Trebek said he has sometimes been in "excruciating pain," and often suffers from fatigue. Mentally, he admits to sometimes feeling a "surge of sadness" and "depression."
"When it happened early on I was down on myself," he said. "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. 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."
Trebek first announced his diagnosis of stage 4 pancreatic cancer in March.
Two months later, he and his doctors announced that he appeared to be winning his battle against the disease. He responded incredibly well to treatments and was in "near remission," his doctors said in May.
"It's kind of mind-boggling," Trebek told People at the time. Even though the overall survival rate for pancreatic cancer is just 9 percent, Trebek responded well to chemotherapy.
"The doctors said they hadn't seen this kind of positive result in their memory - some of the tumors have already shrunk by more than 50 percent," he told the magazine.
But none of this means the beloved game show host is certain to beat the disease. For now, Trebek credits the warmth and support of fans with his inroads against the cancer.
"I've got a couple million people out there who have expressed their good thoughts, their positive energy directed towards me and their prayers," he told People in May. "I told the doctors, this has to be more than just the chemo, and they agreed it could very well be an important part of this."
Because it is so often symptomless until it reaches an advanced stage, pancreatic cancer has a high fatality rate. According to the American Cancer Society, about 57,000 Americans will be diagnosed with the disease in 2019, and the illness is expected to claim nearly 46,000 lives.
As well, pancreatic tumors are particularly aggressive "due to a mutational profile that makes it resistant to therapies that work better for other tumor types," explained Dr. Angela Alistar. She directs gastrointestinal medical oncology at Morristown Medical Center, in Morristown, N.J.
Trebek is philosophical about his chances, and said death doesn't frighten him.
"I realize that there is an end in sight for me, just as there is for everyone else," he told "GMA."
"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.'" Trebek 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 effect 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."
And he said he has no plans right now to quit hosting "Jeopardy!."
"As long as I can walk out and greet the audience and the contestants and run the game, I'm happy," he said.
Born in 1940 in Sudbury, Ontario, Canada, Trebek initially was a TV journalist before hosting a Canadian quiz show, "Reach for the Top." That led to being hired to host U.S. game shows such as NBC's "The Wizard of Odds" in 1973 and "The $128,000 Question," before moving to "Jeopardy!" a decade later.