Cancer cases will soar as the planet's population grows and ages, the World Health Organisation has warned.
The WHO predicts in a new report that the number of cancer diagnoses will reach 24 million a year by 2035 - up from 14 million now.
It says in a report to mark World Cancer Day that the majority of the extra cases will be in the developing world.
As people in poorer countries become more wealthy they are likely to live longer, reaching an age when cancer becomes more likely.
They are also likely to adopt a Western diet high in sugar and fat.
Governments should do more to prevent cancer, the WHO said. Half the future cases could be avoided if people adopt healthier lifestyles.
That view was backed up by the World Cancer Research Fund, which released results from a survey showing that half the UK population is unaware that diet can affect the risk of cancer.
The charity's general manager, Amanda McLean, said: "About a third of the most common cancers could be prevented through being a healthy weight, eating a healthy diet and being regularly physically active.
"These results show that many people still seem to mistakenly accept their chances of getting cancer as a throw of the dice.
"But by making lifestyle changes today, we can help prevent cancer tomorrow."
Meanwhile Cancer Research UK has launched a new smartphone game to help scientists find future cures.
Gamers fly a spaceship through an intergalactic assault course.
But the hazards and targets relate to DNA data from thousands of tumour samples - and the track taken by players will give scientists clues to key variations in the genetic sequences of patients.
Hannah Keartland, the citizen science lead for the charity said: "Our scientists' research produces colossal amounts of data, some of which can only be analysed by the human eye - a process which can take years.
"We hope that thousands of people worldwide will (try) Play to Cure: Genes in Space as often as possible, to help our researchers get through this data."
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