Chance of developing cancer largely down to luck, study suggests

But new research has suggested the majority of cases of the disease are down to little more than bad luck.

The study published in academic journal Science showed random DNA mutations causing cells to divide are responsible for two thirds of cancers in adults, with the remaining third linked to environmental factors or defective inherited genes.

Although the researchers have said smoking or other poor lifestyle choices can add to the risk, Professor Bert Vogelstein from Johns Hopkins University School of Medicine in Baltimore said it seemed bad luck was a bigger factor.

“All cancers are caused by a combination of bad luck, the environment and heredity,” he said.

"This study shows that you can add to your risk of getting cancers by smoking or other poor lifestyle factors.

“However, many forms of cancer are due largely to the bad luck of acquiring a mutation in a cancer driver gene regardless of lifestyle and heredity factors.

“The best way to eradicate these cancers will be through early detection, when they are still curable by surgery."

The study found a strong correlation between the rate of cell division in particular parts of the body and the risk of developing an associated cancer. The more often cells divide, the more likely it is the genetic code will become jumbled, leading to an increased risk of cancer.

The researchers found mutations caused when one chemical letter in DNA was wrongly swapped for another during the cell duplication largely accounted for 22 of the 31 types of cancer involved in the study.

Professor Vogelstein said the remaining nine occurred at a rate that could not been attributed to bad luck.

"We found that the types of cancer that had higher risk than predicted by the number of stem cell divisions were precisely the ones you'd expect, including lung cancer, which is linked to smoking, skin cancer, linked to sun exposure and forms of cancers associated with hereditary syndromes," he said.

He added people who live long, cancer-free lives despite exposure to risks such as smoking are blessed with good luck rather than good genes.

Biomathematician Dr Cristian Tomasetti, who co-authored the report with Professor Vogelstein, said changing habits and lifestyle may reduce the risk of developing some forms of cancer, but would have little impact on others.

"We should focus more resources on finding ways to detect such cancers at early, curable stages," he said.

"I'm not claiming any cancers, overall across the population, are the result of pure chance but what I am claiming is there are some tissues - for example blood cancer - where there is very little evidence of any hereditary or environmental factor.

"Let's say my parents smoked all their lives and they never got lung cancer.

“If I strongly believed cancer was only environment, or the genes that are inherited, then since my parents didn't get cancer I may think I must have good genes. So I would think it would be OK to smoke.

“On the contrary our study says no, my parents were just extremely lucky and played a very dangerous game."

But despite the study’s findings, a report issued by Cancer Research UK has said 600,000 deaths from the disease in the UK could have been prevented by healthier living.

Figures released by the charity have suggested more than four in 10 cancers could be avoided if people made changes to their lifestyles such as quitting smoking, eating more healthily and losing weight.

According to the charity, smoking accounted for more than 314,000 deaths from cancer over the past five years, while a further 145,000 could have been prevented if more people ate a more balanced diet.

Maintaining a healthy weight could have prevented around 88,000 cases, while tens of thousands of cancers were linked to excess alcohol, failing to protect the skin from sun, and lack of exercise.

Cancer Research UK statistician based by Queen Mary, University of London Professor Max Parkin, whose work provided the basis of the report, said research carried out around the world had all lead to the same conclusion – that lifestyle choices had a significant impact on cancer risk.

"Of course everyone enjoys some extra treats during the Christmas holidays, so we don't want to ban mince pies and wine,” he said. “But it's a good time to think about taking up some healthy habits for 2015.

"Leading a healthy lifestyle can't guarantee someone won't get cancer, but we can stack the odds in our favour by taking positive steps now that will help decrease our cancer risk in future."

The charity’s expert on cancer prevention Professor Linda Bauld said each of the more than 200 types of the disease were caused by a complex set of factors including both lifestyles and genes.

"There are proven ways to minimise our risk of cancer like giving up smoking, being more active, drinking less alcohol and maintaining a healthy weight,” she said.

"We must make sure the public and the policy-makers know the evidence behind the benefits of these lifestyle changes is solid."

Cancer Research UK chief executive Harpal Kumar said evidence had shown cutting smoking rates in the UK by just one per cent could save 3,000 lives a year.

“But changing our habits isn't easy,” he said.

"That's why we've made it a priority to invest in more research so we can learn the best ways to help people make healthier choices to reduce their cancer risk in later life."

Meanwhile, former editor of the British Medical Journal Richard Smith has said he believes cancer is the best way to die.

In an article published in the journal the 62-year-old wrote, while many people had told him they would prefer to die suddenly, he believed this could be harder on loved ones. But having the chance to reflect on life before it ends could be a valuable experience.

"The long, slow death from dementia may be the most awful as you are slowly erased, but then again when death comes it may be just a light kiss,” he wrote.

"Death from organ failure - respiratory, cardiac, or kidney - will have you far too much in hospital and in the hands of doctors.

"So death from cancer is the best.

“You can say goodbye, reflect on your life, leave last messages, perhaps visit special places for a last time, listen to favourite pieces of music, read loved poems, and prepare, according to your beliefs, to meet your maker or enjoy eternal oblivion.”

Mr Smith added he recognised this was a romantic view of death, but said it was achievable with “love, morphine, and whisky” and was far preferable to going through a difficult and potentially futile series of treatment.

“Let's stop wasting billions trying to cure cancer, potentially leaving us to die a much more horrible death," he said.

For advice on giving up smoking, losing weight or maintaining a healthy lifestyle, talk to your GP.