Alex Trebek has announced that he is returning to chemotherapy. The “Jeopardy!” host previously completed a cycle of chemo for his stage 4 pancreatic cancer earlier this year.

“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 “Good Morning America” on Tuesday. “I lost about 12 pounds in a week. And my numbers went sky high, much higher than they were when I was first diagnosed.”

That means Trebek must go through another cycle of chemotherapy to control the pancreatic cancer. “So, the doctors have decided that I have to undergo chemo again and that's what I'm doing, and it has different effects on you,” he said.

The host openly discussed how the treatment is difficult. He hasn’t gotten his strength back yet. He described the “excruciating pain,” fatigue and nausea as well as bouts of depression. Still, he tries to look on the bright side. “The thing that gives me the most optimism is, hey, I’m still here,” he said.

In another video directly addressing viewers, Trebek recalled his happy return as Season 36 kicked off. “That was a big premature and certainly overoptimistic…It appears I will be having more chemo treatments ahead of me. Hey, they worked very well the first time, so we’re expecting good results again. But please keep me in your good thoughts and prayers.”

Trebek announced in March his “plan to beat the low survival-rate statistics” for pancreatic cancer.

The 79-year-old told interviewer T.J. Holmes that he knows that he had a good long life and isn’t frightened of death.

Trebek added that he has had no discussions about retirement. Trebek will continue to host “Jeopardy!” as long as he is able. He didn’t miss a single day of work during his first round of treatment.

Alex Trebek
Alex Trebek of "Jeopardy!" fame is pictured during a rehearsal for the shows Power Players Week in Washington, D.C., on April 21, 2012. Kris Connor/Getty Images