The host of 'Jeopardy!' Alex Trebek announced some shocking news in a YouTube video that was posted on March 6 revealing he has been diagnosed with stage 4 pancreatic cancer.

78-year-old Trebek found out about his condition earlier this week. "Now, normally, the prognosis for this is not very encouraging, but I’m going to fight this, and I’m going to keep working. And with the love and support of my family and friends and with the help of your prayers also, I plan to beat the low survival rate statistics for this disease," he says in the video.

He then jokingly says that he will "have to" recover because he is bound by contract to fulfill his hosting duties for three more years. "Truth told, I have to! Because under the terms of my contract, I have to host 'Jeopardy!' for three more years! So help me. Keep the faith and we’ll win. We’ll get it done. Thank you," he says.

Trebek, a native of Sudbury, Ontario, Canada, has been host of the syndicated quiz show since 1984. He and his wife, Jean Currivan, have two children.

Ken Jennings, a longtime 'Jeopardy!' player who took part in the show's 'All-Star Games' that ended March 5, posted a tweet in which he compared Trebek to the late TV journalist Walter Cronkite. "I've said this before but Alex Trebek is in a way the last Cronkite: authoritative, reassuring TV voice you hear every night, almost to the point of ritual," Jennings wrote.

Trebek has gone online before to get out word about his health. In January 2018, he posted a video announcing he'd undergone surgery for blood clots on the brain that followed a fall. The show was on hiatus during his recovery. In 2007, he was hospitalized for about a week after suffering what was described as a minor heart attack.

The show has yet to bring in a substitute host for him — save once, when he and 'Wheel of Fortune' host Pat Sajak swapped their TV jobs as an April Fool's prank. In a Twitter post, Sajak wrote "There is no one I know who is stronger and more determined, and I would never bet against him. We, and the entire country, are pulling for you, Alex."

Trebek, the smoothest of TV game show hosts, admitted to a case of nerves during rehearsals in January for the show's first-ever 'All-Star Games', a team-play tournament that made new demands on its host. "This will probably start me drinking again," he joked. Although Trebek had publicly toyed with the idea of retiring, he instead renewed his deal in 2018 with Sony Pictures Television for three more years, through the 2021-22 season.

In an interview with The Associated Press in January, Trebek discussed his decision to keep going with 'Jeopardy!'. "It's not as if I'm overworked — we tape 46 days a year," he said. But he noted he's been working on TV for more than 50 years and was, as he put it, "78-and-a-half now. I'm slowing down."

"It's logical to start thinking about retiring," he said. "And I will someday, when I feel I've lost enough of my abilities and am messing up a little too much, or it's no longer any fun." "And it's still fun," he said.

Trebek, who holds a philosophy degree from the University of Ottawa, was a TV and radio reporter for the Canadian Broadcasting Corp. before moving to the United States. He became a US citizen in 1998. He's won five Emmys as best game show host and received a lifetime achievement award from the TV academy in 2011.

Created by entertainer-producer Merv Griffin, 'Jeopardy!' debuted as a NBC daytime show in 1964 with host Art Fleming and ran for more than a decade before going into syndication. The version with Trebek shifted the show largely into early evening slots.

—With AP inputs