At least 13,000 premature deaths from cancer could be prevented each year in the UK, says the World Cancer Research Fund (WCRF).
It says the government could do more to raise awareness of how people can reduce their cancer risk.
The announcement comes as a survey showed that a third of Britons still believe that developing cancer is due to fate.
About 157,000 people die of cancer every year in the UK.
Although the mortality rate is predicted to continue declining, due to a growing and ageing population the number of deaths is expected to rise to about 182,000 deaths by 2025.
The WCRF survey of more than 2,000 adults suggested that 28% of people think there is little that can be done to prevent cancer.
But Dr Kate Allen, executive director of science and public affairs at WCRF, said: “These results are a real concern because they show that a significant proportion of people don’t realise that there’s a lot they can do to reduce their risk of cancer.
“By eating healthily, being physically active and keeping to a healthy weight, we estimate that about a third of the most common cancers could be prevented.
“Everyone has a role to play in preventing cancer but governments and health professionals are key to raising awareness and making it easier for individuals to change their lifestyle habits.”
The Union for International Cancer Control, a non-governmental organisation working across 155 countries, estimates that 1.5 million lives could be saved worldwide if urgent action is taken to raise awareness about cancer.
Otherwise, it says, there could be six million premature cancer deaths by 2025.
The UICC and the WCRF want governments and the public to dispel four important myths and misconceptions about cancer, namely that cancer is just a health issue, that it is a disease of the wealthy, developed countries, that it is a death sentence and that getting cancer is down to fate.