Alex Trebek is experiencing "moments of depression" in his cancer battle.

Alex Trebek

Alex Trebek

The 'Jeopardy!' host announced his stage four pancreatic cancer diagnosis in March, and although he was said to be nearing remission after undergoing chemotherapy, he was told in a doctor's appointment in September that his "numbers [are] sky high", so he needs to resume the treatment.

And Alex has now admitted his ongoing struggle with the disease has had an impact on his mental health.

He said: "I don't mind getting choked up. My oncologist told me one of the symptoms, if you will, of pancreatic cancer is that you get these moments of depression, sadness."

As well as being tough on the 79-year-old presenter, the diagnosis has also been difficult for Jean, his wife of 29 years.

Alex added in an interview with ABC's Michael Strahan: "It's always tough for caretakers, because she has to deal with her worrying about my well-being and also dealing with ... I'm not always the most pleasant person to be around when I'm experiencing severe pain or depression, and she has to tread lightly around me."

The TV star revealed earlier this year he has a "close-ended life" because of his cancer battle, as the survival rates of pancreatic cancer are so low.

He said: "I have learned something in the past year and it's this: We don't know when we're going to die. Because of the cancer diagnosis, it's no longer an open-ended life, it's a closed-ended life because of the terrible ... survival rates of pancreatic cancer. Because of that, and something else that is operating here, people all over America and abroad have decided they want to let me know now, while I'm alive, about the impact that I've been having on their existence."

And whilst he's still committed to hosting 'Jeopardy!', he has said he doesn't know how much longer he can stay in the role.

He explained: "I can be sitting in my dressing room and I get up and I'm not able to move, but then all of a sudden when Johnny says, 'Now here is the host of Jeopardy!, Alex Trebek,' OK, lets go! I will keep doing it as long as my skills do not diminish, and they have started to diminish."