new sense of purpose. Reporter: With the host in the guinness book of world records, for 36 years, it's been appointment TV. Their day starts early. Right on time, five minutes to 6:00. Reporter: First order of the day, answering e-mails and fan letters. He has been getting more of them since his pancreatic cancer diagnosis. I wondered how courageous a human being I was. I look at it as it's part of life. Does that mean I'm courageous because I'm dealing with it? No. I can be scared to death and I'd still have to deal with it, but I'm not scared to death. So maybe I am courageous. Way to go, Alex. This week, I was diagnosed with stage four pancreatic cancer. Reporter: In March, he told the country. I join forces with the world pancreatic cancer coalition. Reporter: In October, he told us what to watch for. Mid back pain. Unexplained weight loss. New onset diabetes. Reporter: Jean and Alex trebek have been married 29 years. They have two adult children. What's the toughest part for both of you. I think for me it's when I see him in pain and I can't help him. And when he doesn't eat right. When he has too much diet soda. Back off, Michael. It's always tough for the caretaker. Because she has to deal with her worrying about my well-being. Reporter: After encouraging results from his first round of chemo, his medical condition worsened. He decided he would try whatever comes next. I don't mind experimenting. I've got nothing to lose. So let's go for it. Reporter: The cancer diagnosis shifted his world. Most of us have open-ended lives. 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 close-end life. Because of the terrible statistics, survival rates for pancreatic cancer. And 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. Reporter: I'm just happy that people are able to express it right now. They have come out, and they have told me, and my gosh, it makes me feel so good. He's being so gracious and calling people and writing letters. He's playing the hand he's been dealt, and he is really playing it so beautifully. I thought you guys might like my sharing something. Reporter: It's a letter from a viewer. I just wanted to thank Alex for speaking about his symptoms. Thank you, Alex. My brother-in-law decided because he was experiencing some of the same symptoms to go and see his doctor. Today he found out that he has stage one pancreatic cancer. Looks like it's very treatable. So I wanted to say thank you, because I really feel like you saved his life. God bless you, Alex. That's kind of nice. So that made me feel pretty good. Reporter: Yeah, you saved somebody's life. Absolutely. Reporter: In a taping day filled with nerves, lights and cameras, it just doesn't come up much. Stage four pancreatic cancer, a disease that only a lucky few survive. But Alex trebek isn't shy about neither are contestants. Here comes final jeopardy. The category was famous phrases. Drew guare wrote, what is we love you Alex. That's very kind of you. Thank you. Cost you 1995. You're left with about $5. I read it first, and then I got choked up. Because it suddenly registered on me, oh, dear. Okay. 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, of sadness. That's not to say that all of the negative symptoms I'm experiencing are because of the they're all because of the chemo. I've told people time and time again. Cancer won't kill me, the chemo will kill me. And we'll see. Reporter: Next week will be a homecoming for three "Jeopardy" legends. The greatest of all time. James holzhaur. Reporter: Do they make questions harder for these I hope so. All of us are going to come in with a great knowledge base. Who's got the guts to go in with a daily double. That is going to be fascinating for the viewers because of the quality of these three players. Reporter: His greatest of all time tournament starts next week. He said he'll stay on the show as long as his skills aren't diminished. But there's one thing the 79-year-old man with all the answers just doesn't know, when his last show will be. You alluded a little bit about retire what it's going to be like to announce your last winner, to announce your last show and to walk off that stage and you're done? With "Jeopardy." Mm-hm. Reporter: What do you imagine that will be like? It will be a significant moment for me, but I've kind of, in my mind, rehearsed it and what I would do on that day is tell the director, time to showdown, leave me 30 seconds at the end. And I will say my good-byes. I will tell people, don't ask me who's going to replace me, because I have no say in that whatsoever. But I'm sure if you give them the same love and attention and respect that you have shown me for the past 30-however many years, then they will be a success, and the show will continue being a success. And, until we meet again, god bless you, and good bye.