Transcript for Howard Stern on how a cancer scare changed his life

His new book is out tomorrow. A collection of his best and worst interviews. A reflection on how he's evolved over the years and it's a revealing look at a man I'm lucky to call friend if we're such an odd couple. It's my interview. This is Reporter: Meet the Kinder gentler Howard Stern. The old Howard before intensive therapy, his wife Beth and his Sirius XM show, he says he's embarrassed by that guy now. My attitude was it was a scorched Earth policy. I'm going to blow you out of the you know, for years I used to think, well, I'm one type of person on the air and off the air I'm somebody else. I describe in my book I was ward cleaver off the air. You know, go home to the kids and all that stuff. Live on Long Island but the truth is that was me. Reporter: The new Howard tries to be a more generous and thoughtful interviewer. You learned Lebron James will come on the program. What is the first thing you do. First thing I do is I try to -- I'm honest. I'm not a sports fan. So for me what is it I'm really interested in. I'm probably more interested in his home life, I'm interested in his climb, hmm. How did he get to where he is? What motivates him, what's his drive and really I guess what I'm doing is it's my own self-exploration. If somebody asked me that, I think it would be an interesting how did you get to the neck level? How do you separate yourself from the millions of guys who are doing radio? For a long time for you that was using the people you were interviewing as props. That's your word is there that's what I describe in the book. That's why it's painful for me to look back on that. Reporter: Especially painful ab interview with robin Williams back in the '90s. I describe that when robin Williams came in, who is one of the most magnificent human beings in the world, who is a tremendous talent, I'm lucky to -- The worst interview you ever did. The worst I ever did. I whew him out of the water. I'm thinking I'm the most important thing here. If robin Williams goes on about something, my audience will tune out. I have to keep their interest and he comes into my studio and what do I do? I go, hey, I read you're missing weeks with your nanny. You left your wife for your nanny. That's clobbering someone over the head. It doesn't lead to discussion. It was insulting to him. But all I cared about was being the man. So when you walked off the air that day you said, I nailed it, I got it? Yeah. Yeah. I had -- I was clueless. Reporter: The one he likes best, conan o'brien in 2015. Do you suffer from depression? I mean do you -- are you medicated. I'm medicated the. I used to think I needed to be incredibly unhappy to be funny. When I was interviewing conan because I was able to listen and not be trying to insert myself I picked up on something he said and then all of a sudden he started talking about that he suffered from depression and we got into this heavy thing and it was -- it was like the cameras disappeared. The microphones disappeared and the two of us were just locked in conversation. The best interview you ever Best interview I ever did but people always ask me that is the best interview I ever did. The reason I chose him as the best one in the book, I felt satisfied. I went home that night, do you ever have this -- you interview someone and you go, why didn't I ask him that? Why didn't I think of that. I forgot to say this. Here's what happened. I went home and I went why am I having that feeling because I felt we had put everything on the table. What's it like to be at Howard's table off the air? My wife Ali and I love it. This might be a shock. George and I are friends and get together for dinner with our wives quite often at my house. Full disclosure. George is one of the best dinner guests but you always cause fights at these dinner parties. I cause fights? You and your wife. I love your wife. I love my wife. We all love your wife. And -- You and Beth don't fight. No, Beth and I don't fight but you cause a little bit of a rift. Maybe this is too r-rated for your show. If I'm saying out of line -- This is my wife's mythmaking. We're sitting at dinner and Ali will say and George is an intellectual. She's some sort of Rhodes scholar. Weren't you almost a priest? This is me. We knew this would happen. Inevitably, Ali will go, George and I have sex. Oh. Every night. I'm like and George sits -- George doesn't laugh. He just sit there is like this -- you never let on. I don't know what's going on and then after you leave, you and Ali leave, I go to Beth. I go, did you hear that? Now, I'm going to tell you my wife, I love her. She's a wonderful woman. A beautiful woman. We have sex, you know, you know like normal couple, George. You know, I didn't know -- and I never think of you as a sex fiend but I'm like -- I say did you -- Ah. Can you picture and George and Ali. Completely hijacked right here. Oh, my god. Robin, look at George. I can't look at George right now. Can we get makeup? Let's talk about his interview. We have -- You are sweating. Of course, I am. How did you all become such good friends. Ali met Beth and we had dinner. You're not coming to my house for dinner. Ginger, save George. Save him. We'll be right back.

This transcript has been automatically generated and may not be 100% accurate.