Majority of cancers caused by 'bad luck', not genes or lifestyle, scientists discover
Bad luck plays a bigger role in the development of cancer than previously believed - and two-thirds may be unavoidable, even if you live a healthy life.
A new study by US scientists says we should blame "bad luck" more often when cancer strikes - rather than our own habits.
The culprit is our own genetic code when cells divide out of the blue, new research shows.
Each time a normal cell divides and copies its DNA to produce two new cells, it makes multiple mistakes.
"These copying mistakes are a potent source of cancer mutations that historically have been scientifically undervalued, and this new work provides the first estimate of the fraction of mutations caused by these mistakes," said the research by John's Hopkins University in the journal 'Science'.
However, Irish scientist Seamus Martin, professor of Medical Genetics at Trinity College, yesterday said that while the study added to our insight into cancer we should still avoid risk factors such as smoking, soaking up the sun, drinking too much alcohol and try to maintain a healthy diet and weight.
Even allowing for the element of chance, we could still improve our roll of the dice and reduce the odds of developing many cancers, he said.
"It adds to our knowledge but the advice remains the same," he said.
At least 50pc of major cancers are preventable and there were established links between lung cancer and smoking, he pointed out.
The more we damage our body by unhealthy habits, the more risk we are of developing cancer mutations.
The US researchers said the remaining third of cancer types were affected by lifestyle factors, viruses or a heightened family risk.
The common types of cancer - breast and prostate - were not analysed as the researchers could not find a consistent rate of stem cell division in those tissues.
Lead researcher Bert Vogelstein said that, overall, 66pc of cancer mutations resulted from copying errors.
Another 29pc were from lifestyle factors, and just 5pc from the genes we inherited.
"We need to continue to encourage people to avoid environmental agents and lifestyles that increase their risk," he said.
"However, many people will still develop cancers due to these random DNA copying errors, and better methods to detect all cancers earlier, while they are still curable, are urgently needed."
Smoking accounts for a fifth of all cancers worldwide.
Early detection improves the chances of most patients beating the disease - hence the need for countries like Ireland to ensure that people who have potential symptoms are checked as early as possible.
The US study is aimed at getting a better under- standing of cancer mutations which in turn help in the development of ways to detect the cancer as early as possible.
The latest study came as thousands of volunteers took to the streets yesterday as part of the Irish Cancer Society's 30th Daffodil Day.
"It is still too early to say how Daffodil Day 2017 has performed or if the bus strike impacted, but initial reports from around the country are positive and the glorious sunshine was a welcome addition," a spokeswoman said.
"It will take some time for all donations to come in and until then we won't know if we will reach our Daffodil Day target of €3.98m.
"Daffodil Day is the biggest fundraiser of the Irish Cancer Society. The society raises 98pc of its income from donors."