NDP Leader Jack Layton says he is determined to remain as party leader after being diagnosed with prostate cancer, telling a news conference in Toronto that will not give in to the disease.

"This year, more than 25,000 Canadian men are going to be diagnosed with treatable prostate cancer," said an upbeat Layton, flanked by his wife and fellow NDP MP Olivia Chow. "And I've recently learned that I'm one of them."

"I'm a fighter and I'm going to beat this."

Layton, 59, said he had been diagnosed with the same cancer that his father, former Conservative cabinet minister Robert Layton, successfully overcame 17 years earlier.

"I intend to bring to this battle the same sense determination and optimism that he did," Layton said. "I'll have his genes on my side as well."

Robert Layton died in 2002 at age 76 from Parkinson's disease.

Chow successfully fought off thyroid cancer and has been cancer-free since 2005.

The NDP leader has already started a program of treatments for the cancer and said so far the treatments are going well. "Everything is on track and I'm feeling good."

Layton did not take questions from reporters at the news conference, but said he did not intend to let the disease slow him down. He did acknowledge that: "I'll have a little more time to watch the Olympics on TV and so I can be inspired by our athletes … they'll inspire all of us."

He appeared to have no doubts about continuing to lead the federal NDP while fighting cancer.

"I have an amazing team, I have great friends I have an incredibly supportive family," he said. "Without question we've accomplished a lot but there's a lot more to do … and I can't wait to roll up my sleeves on Monday morning and get started."

Liberal Leader Michael Ignatieff said in a statement that he wished his political rival a swift recovery.

"We all know how combative Jack is and we know that he will face this challenge with his usual determination," said Ignatieff. "I wish him strength and courage on the road to recovery, and I know all Canadians stand behind him in this fight."

Prime Minister Stephen Harper said he called Layton after hearing news of his illness, wished him all the best, and said he hopes to be battling the NDP leader politically for many years into the future.

The announcement came only a few days after Layton cancelled a speech he was to deliver this weekend to NDP leaders from across the country. His office said he had injured his back at the gym.

Dr. Neil Fleshner, head of urology at Toronto's Princess Margaret Hospital, said Layton should stand a good chance of beating the illness, providing he has been diagnosed in good time.

"Assuming it's found early, there's really no reason why he couldn't continue all of his duties," Fleshner said, adding that one in six Canadian men will be diagnosed with prostate cancer in their lifetime.

A former university professor and Toronto city councillor, Layton has built up the NDP's popularity since he took over as leader in 2003, growing the party's share of the popular vote and raising its seat count in the House of Commons to 37.

That is just 6 seats short of the party's all-time high in the 1970s under former leader Ed Broadbent.

With files from The Canadian Press