"I sent him a message saying, 'I know you can get through this,' and, 'Don't listen to stage four and all of (that),'" she told "Entertainment Tonight." "'Don't read the statistics and stay focused and see how you can heal yourself.'"
"That helps. Sense of humor is vital," she continued. "He has a great attitude and a great sense of humor about it and I'm sure he'll do very well."
Newton-John has managed to maintain a sunny outlook despite her illness, and has even said she has a unique way of referring to it.
"Winning over," she recently told TODAY. "I think, you know, what you think creates your reality. So it's a decision. You have to make that decision. You can be a victim, or you can be a winner and enjoy your life."
That may be good advice for Trebek, who endured his own health issues prior to the cancer diagnosis.