Alex Trebek has thanked fans for the ''hundreds of thousands'' of messages of support he's received following his cancer diagnosis.

The 'Jeopardy!' host announced earlier this month that he had been diagnosed with stage 4 pancreatic cancer and admitted he has been ''extremely touched'' by the outpouring of kindness.

He said in a video message: ''I just wanna take a few moments to say thanks to the, believe it or not, hundreds of thousands of people who have sent in tweets, texts, emails, cards and letters wishing me well following my recent health announcement.

''I am thankful for the kind words, the prayers and the advice you have offered, and I'm extremely touched by the warmth you have expressed in your comments to me.''

The 78-year-old presenter admitted he wouldn't ''be able to respond to all of you individually,'' but promised he does read ''everything'' that gets sent to him - including a get well card from IBM computer Watson, which once competed on the game show.

He concluded: ''I'm a lucky guy.''

Alex previously vowed to do everything he could to fight the disease, even though he knows the prognosis is ''not very encouraging''.

He said in a video message to fans: ''Hi everyone, I have some news to share with all of you. And it's in keeping with my longtime policy of being open and transparent with our 'Jeopardy!' fanbase. I also wanted to prevent you from reading or hearing some overblown or inaccurate reports regarding my health.

''So therefore, I wanted to be the one to pass along this information. Now, just like 50,000 other people in the United States each year, this week I was diagnosed with stage 4 pancreatic cancer.''

''Now normally the prognosis for this is not very encouraging, but I'm going to fight this and I'm going to keep working.''