Most cases of cancer are down to unhealthy lives, rather than bad genes, doctors in the UK said.
They said that factors in the world around us, from diet, to sunlight, cigarettes and disease, play a far bigger role in fuelling cancer than dodgy DNA.
Up 90 per cent of cancer cases would be wiped up if all these triggers could be avoided.
Dr Smith, of Cancer Research UK, said: ‘Healthy habits like not smoking, keeping a healthy weight, eating a healthy diet and cutting back on alcohol are not a guarantee against cancer, they do dramatically reduce the risk of developing the disease.’
While the advice may not seem surprising, scientists are divided about how much cancer is caused by what we do and how much is unavoidable.
The controversy was stoked a year ago by research that claimed that most cases are caused by errors in DNA that are generated at random as the body ages and its cells divide.
The researchers said this meant that most cases of cancer were down to ‘bad luck’, rather than an unhealthy lifestyle.
The latest study involved four analyses of the causes of cancer and used some of the same data as the first piece of research.
However, it came to the opposite conclusion.
Dr Yusuf Hannun, of Stony Brook University in the US, said that while luck plays a role, factors in the world around us are much more important.
These include diet, alcohol, cigarettes, sunburn, some viruses, pollution and likely other factors that have yet to be identified.
Writing in the journal Nature, he said that the genes we inherit from our parents only account for a very small number of cancer cases.
He concluded: ‘These results are important for strategizing cancer prevention, research and public health.’
Other experts said he had built a ‘compelling case’ for his argument.
Professor Kevin McConway, of the Open University, said: ‘The authors’ aim is to calculate what percentage of cancers would not arise, if we could wave a magic wand and get rid of all possible external risk factors.
‘There would still be cancers, because of the way that cells divide in the body. But there would be fewer of them.’
Dr Jian-Min Yuan, of the University of Pittsburgh in the US, said: ‘These results demonstrate that a large proportion of cancer is caused by environmental factors and are preventable if their underlying causes are identified.’