Stynes regularly defied injury through his 12-season playing career, but will temporarily step away from the Demons presidency to fight the disease, after having a cancerous lump removed from his back three weeks ago.

''I've got a new focus ... and as you've seen with my footy, I don't intend to hold much back,'' Stynes, 43, said yesterday.

''When I've got a goal, a vision, a focus, I go after it and do everything I can to make it happen and right now I need to put all my energies into getting my body right and to heal.

''My body has something in it that it needs to release and I need to find a way of doing that.''

Fighting to hold back emotion, Stynes said after initially hoping the disease was confined to his back, doctors found it had spread elsewhere.

''I thought it might be located in the one area but it's not, it's spread quite a bit,'' he said.

''I need to put all my energies into getting my body right and to heal.

''I'm not stepping down from Melbourne but I will be taking a break I will have to take the rest of the season off.''

Flanked by his wife Sam, Demons chief executive Cameron Schwab and vice-president Don McLardy, Stynes said he would go into hospital as soon as possible to begin therapy.

McLardy will take over as acting president until the end of the season.

Irish-born Stynes came to Australia in the mid-1980s and went on to have a decorated VFL/AFL playing career.

He played 264 games with Melbourne, including a league-record streak of 244 straight, won the 1991 Brownlow Medal and is a member of the AFL Hall of Fame.

Stynes took over as Demons president 12 months ago when Paul Gardner stepped down.

Prime Minister Kevin Rudd led the well-wishers for Stynes, who has also won great admiration for his work with the Reach Foundation, a youth charity he established.

Stynes, who has two children, has been named Victorian of the Year and won an Order of Australia Medal for his charity work.

''When you've got great Australians like Jim Stynes, I think it's really important that the country gets behind them, provides them with positive support and encouragement,'' the Prime Minister said.

''I wish him all the very best in what will be a tough fight ahead but I think a person of his stamina and quality is uniquely qualified to engage in and to succeed in.''

AFL chief executive Andrew Demetriou said all those in the football industry were united in their support for Stynes.

''Jim is one of the most respected people in football and across the community and the best wishes of the AFL and all football supporters go out to him, his wife Sam and his family at this time,'' Demetriou said.

Stynes was taking on the challenge with a positive outlook.

''I was having a conversation with a young girl, but a very wise girl and she said to me 'this could be the greatest blessing that you've ever got because part of your soul needs to communicate something to you and this is obviously the way it needed to do it','' he said.

''You know me, I run a million miles an hour and I don't always stop to smell the roses and take in what's actually happening around me.

''I'll be back with a lot more balance.''