Dr Harpal Kumar, the charity's chief executive, said: "It's not very long ago that cancer used to be thought of as a death sentence.
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"The reason this 50 per cent figure is an important tipping point is it's saying that, actually, now half of all patients will survive at least 10 years after a diagnosis - and for many it will be very much longer than that. I think that does represent a change in the way we should be thinking about cancer."
After a decade, survivors were no more likely to die of the disease than anyone else. Professor Michel Coleman of the London School of Hygiene and Tropical Medicine, said: "As a whole, patients who have survived that long no longer have any different chances of surviving than the rest of the population - in that sense, it would represent a 'cure'?''.
The study, based on data from more than 7 million adults in England and Wales diagnosed between 1971 and 2011, showed long-term increases in one, five and 10-year survival.
An "all-cancers survival index'' was calculated that combined figures for 17 types of cancer. The length of time half of cancer patients could expect to live had risen from just one year in 1971-72 to five years in 2005-06, and 10 years for those diagnosed in 2010-11, the study found.
The data shows dramatic improvements in survival rates for some of the most common forms of the disease, including cancers of the breast, prostate and testes.
Rates of 10-year survival for testicular cancer rose from 69 cent to 98 per cent, and for malignant skin cancer from 46 per cent to 89 per cent.
Women with breast cancer now have a 78 per cent chance of surviving at least a decade, compared with 40 per cent in 1971, the data shows.
Meanwhile, the proportion of men living at least 10 years with prostate cancer rose from 25 per cent to 80 per cent.
Dr Kumar said: "Twenty years from now we want to see three quarters of all patients surviving at least 10 years following a diagnosis of cancer. That's a big step forward from where we are today, but we firmly believe that's achievable.
However, survival rates in Britain were still lagging behind those in many countries in Europe, researchers said, with too many cases being missed by GPs and less effective treatment after diagnosis.