Alex Trebek is "doing well" and "feeling great".

Alex Trebek

Alex Trebek

The 'Jeopardy!' presenter has been battling pancreatic cancer for over a year and though his treatment leaves him feeling tired, the 79-year-old star is pleased it is proving effective because his "numbers are good" and he's been working hard on his memoir.

He said in a video posted to the 'Jeopardy!' Twitter account: "I'm doing well. I've been continuing my treatment and it is paying off though it does fatigue me a great deal. My numbers are good. I'm feeling great.

"In fact, during the break from the studio, I even wrote a book that will be coming out July 21st."

Alex - who has Emily, 26, and Matthew, 29, with wife Jean Currivan - first spoke about his cancer battle in March last year, and while he was pleased to pass the one-year survival marker four months ago, he has experienced "massive attacks of great depression" throughout his journey.

In a video posted to Twitter, he said: "The one-year survival rate for stage four pancreatic cancer patients is 18 percent. I'm very happy to report I have just reached that marker. I'd be lying if I said the journey had been an easy one.

"There were moments of great pain, days when certain bodily functions no longer functioned, and sudden massive attacks of great depression that made me wonder if it really was worth fighting on."

Alex said he "brushed aside" his mental health struggle for the sake of his wife Jean, whom he credits with "giving her all to help [him] survive".

The game show host also claimed he needed to be strong for other cancer sufferers who have looked to him as an "inspiration and cheerleader".