Half of the UK population will develop cancer at some point in their lives, a new forecast from Cancer Research UK has shown.
The estimate replaces the previous figure which using a different calculation method had said a third would develop cancer during their lives.
The rise was attributed to increasing longevity, with over 60% of cases diagnosed in those aged over 65.
The research compared the risk for men and women born in each year between 1930 and 1960 and covered all cancers except non-melanoma skin cancer.
For men born in 1930 the risk of cancer was 39% while for those born in 1960 it was 54%, while for women the rate increased from 37% for those born in 1930 to 48% for those born in 1960.
Those born in the early 1960s and later have a cancer risk of 1 in 2.
In the last 40 years survival rates have doubled, meaning about half of patients with cancer will survive the disease for more than 10 years.
Professor Dame Sally C Davies, chief medical officer for the government, said: "We must set these figures in context of the fact that people are living longer because of better healthcare and medical advances.
"Cancer survival rates have improved to record levels in this country and we are working to raise awareness of cancer symptoms so it can be diagnosed earlier, improving cancer outcomes."
She conclded: "Leading a healthy lifestyle is easily the most effective thing you can do to reduce your risk, this means being active, quitting smoking, drinking less alcohol, and having a balanced diet."
Harpal Kumar, chief executive of Cancer Research UK, said: "We need a concerted approach and a broader sense of how we can save lives and money by preventing more cancers.
"Growing older is the biggest risk factor for most cancers - and it's something we can't avoid."