Up to 90% of cases ‘could be wiped out by avoiding triggers caused by our unhealthy lifestyles’
Most cases of cancer are down to unhealthy lives, rather than bad genes, doctors said last night.
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 Emma 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.
It said that for or two out of three cancer victims, the cumulative effect of random mistakes in genes is to blame for the disease rather than poor choices about how they lived their lives or ‘chose’ their parents.
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, suggesting that cancer incidence is far too high to be explained by simple mutations in cell division alone.
They said that, if random mutations were to blame, there would be far fewer cases of cancer than there are.
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.
Previous studies have shown that people moving from low cancer incidence to countries with high cancer rates develop the same tumour incidences, which also suggests the risks are caused more by environment than genes.
Scientists also looked at patterns in the mutations associated with certain cancers and found that mutations during cell division rarely build up to the point of producing cancer, even in tissues with relatively high rates of cell division.
The team found that some exposure to environmental factors would be needed to set off the disease.
The Johns Hopkins University study earlier this year also failed to include common cancers such as prostate, breast, stomach, and cervix, which have been heavily linked to environmental causes.
In 2012, there were almost 339,000 of new cancer cases of cancer recorded and almost 162,000 deaths, according to figures from Cancer Research UK.
The chances of beating cancer in England is improving but still lags behind countries elsewhere in Europe, official figures revealed last month.
Previously experts have estimated that 30-40 per cent of cancer cases would be avoided given a better lifestyle, but there has been no similar calculation about whether the remainder can be prevented.
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.’