Researchers say that up to 90% of cancers are caused by our behaviours
Up to 90% of cancers are caused by modern lifestyle choices such as smoking, drinking and spending too much time in the sun, according to a new study.
The findings contradict research published earlier in the year which claimed that two-thirds of cancers were caused simply by "bad luck".
In the latest study, doctors at the Stony Brook Cancer Center in New York used computer modelling, genetic information and population statistics to reach their conclusions.
Speaking to Sky News, Dr Yusuf Hannun - the director of the clinic - said: "Is cancer just an issue of bad luck? At some level it is. But that bad luck can also include a lot of modifiable factors.
"For example, we may be born with a gun that has one bullet in the chamber that can cause cancer, so we'd have a one in six chance of getting cancer over a lifetime.
"But if you start smoking or lying under the sun excessively, it’s the equivalent of adding three more bullets to the chamber.
"That person still has a probability of not getting cancer, but they’ve increased significantly - they’ve doubled or tripled or quadrupled - their possibility of getting cancer."
The Stony Brook research team say that their data proves that only 10% to 30% of cancers are caused by intrinsic factors, such as DNA.
This new study, published in the journal Nature, adds credibility to public health advice which says that maintaining a healthy weight, avoiding pollution and sunburn, and not smoking or drinking heavily are the best ways to prevent cancer.
The paper came to the following conclusions about the split between environmental and natural causes for certain types of cancer:
In an earlier study from January, researchers at the Johns Hopkins University School of Medicine in Baltimore looked at 31 cancer types and found that 22 were generally "bad luck".
These included pancreatic, bone, testicular, ovarian and brain cancers - as well as leukaemia.
The other nine types, including skin cancer known as basal cell carcinoma and smoking-related lung cancer, were more heavily influenced by hereditary and environmental factors.
Overall, they attributed 65% of tumours to random mutations in genes that can spur cancer growth.