Half of all people in the UK will get cancer at some point in their lives, with an ageing population driving up the number of cases.
The latest figures from Cancer Research UK reveal an urgent need to improve public health and NHS cancer services if the UK is to cope with a growing population, report authors warn.
Published in the British Journal of Cancer, the latest estimate replaces the previous figure that said just over one in three people will develop the condition in their lifetime.
Since the 1970s, cancer survival has doubled, with around half of patients now living for 10 years or more. Researchers say age is now the biggest lifetime cancer risk for most forms of the disease.
Study author Professor Peter Sasieni said: "Cancer is primarily a disease of old age, with more than 60% of all cases diagnosed in people aged over 65. If people live long enough then most will get cancer at some point. But there's a lot we can do to make it less likely - like giving up smoking, being more active, drinking less alcohol and maintaining a healthy weight.
"If we want to reduce the risk of developing the disease we must redouble our efforts and take action now to better prevent the disease for future generations."
The authors also warn there is an urgent need to improve NHS cancer services.
Harpal Kumar, Cancer Research UK's chief executive, said the government must plan ahead to make sure services can cope with the influx of cases. "If the NHS doesn't act and invest now, we will face a crisis in the future - with outcomes from cancer going backwards," he said.
"But NHS investment isn't the only answer. 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.
"But more than four in ten cancers diagnosed each year in the UK could be prevented by changes in lifestyle - that's something we can all aim for personally so that we can stack the odds in our favour."
Also commenting on the findings, Professor Dame Sally Davies, England's chief medical officer, 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. 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."