Catherine Zeta-Jones got emotional as she opened up about her husband Michael Douglas' fight with cancer.

The 44-year-old Welsh actress admitted she was a "mess", following the 2010 diagnosis, which led to the 69-year-old star undergoing seven weeks of treatment including gruelling chemotherapy, reported the Daily Telegraph.

"I was a mess. I'll be quite frank, I was a mess," she told the group of 3,000 doctors at the International Federation of Head and Neck Oncologic Societies 5th World Congress in New York.

"When I'm married to a man who has such a conviction for life... he fights to make the wrongs right. For the first time he was fighting for his life."

As the couple took to the stage together at the opening ceremony, Catherine said: "I'm very happy to be here this morning with my husband. I mean that literally. I'm very happy to be here with my husband."

Michael joked that he was nervous appearing in front of so many cancer specialists.

"As long as nobody tells me to bend over and touch my toes and cough we're all going to be just fine," he said. "Generally when I'm on a stage at a prestige event like this I'm accepting some kind of an award. [I'm] grateful not to walk out of here with another prognosis."

He added: "In all seriousness and in every sense of the word. I'm very fortunate to be here today."

The actor, who has been cancer-free since 2011, had a walnut-sized tumour removed from the back of his tongue after initially being misdiagnosed as suffering from throat cancer. He confirmed it was at stage four, the most advanced stage.