Rush Limbaugh says he has been diagnosed with advanced lung cancer

Limbaugh, 69, told his radio audience Monday that he was diagnosed with an advanced stage of the disease. He said the diagnosis was confirmed on January 20.

"I wish I didn't have to tell you this, and I thought about not trying to tell anybody, I thought about trying to do this without anybody knowing, because I don't like making things about me," Limbaugh said. But "there are going to be days that I'm not going to be able to be here, because I will be undergoing treatment, or I'm reacting to treatment."

Limbaugh has been hosting "The Rush Limbaugh Show" in national syndication for 31 years. He is a Republican party icon and a close ally of President Trump's.

The president recently called Limbaugh "a major star who never wavered despite the Fake News Hits he has had to endure. His voice is far bigger than theirs!"

Limbaugh's radio contract was due to expire later this year. He renewed his deal with the syndication company Premiere Radio Networks in early January. CNN Business has reached out to Premiere for comment.

His show "continues to be the most-listened-to national radio talk show in America," Premiere said when he renewed.

Limbaugh's fans expressed shock about the diagnosis on Monday afternoon.

"Say a prayer today for my fellow talker Rush @limbaugh who just announced he has lung cancer and will be undergoing treatment," Lars Larson tweeted. "America needs his voice!"