WATCH: Alex Trebek announces he has stage 4 pancreatic cancer; vows to fight it

Alex Trebek has been diagnosed with stage four pancreatic cancer.

The Sudbury, Ont.-born game-show host announced the news in a video posted on the "Jeopardy!'' YouTube channel.

Trebek says he wanted to announce the news himself to prevent fans "from reading or hearing some overblown or inaccurate reports.''

He acknowledges the prognosis for stage four pancreatic cancer "is not very encouraging.''

But he adds that he's "going to fight this'' and "going to keep working.''

The 78-year-old says with love, support and prayers, he plans "to beat the low survival rate statistics for this disease. I have to, because under the terms of my contract, I have to host 'Jeopardy!' for three more years!"

Trebek has been the host of "Jeopardy!" since 1984.