Study: Lifestyle has a bigger role in causing cancer 01:41

Story highlights

  • “Bad luck” of stem cell mutation is not the primary cancer risk factor, says a new study the journal Nature
  • Environmental and lifestyle factors, which can be modified, are “large risk proportions for cancer,” it says
  • A study earlier this year concluded that heredity and environment could be blamed for only some of the risk

(CNN)The greater majority of cancer may be influenced by environment and lifestyle factors.

That’s what the authors of a new study in the journal Nature argue. External factors such as exposure to toxins and radiation are a major risk factor in developing cancer, the new study says.

“Environmental factors play important roles in cancer incidence and they are modifiable through lifestyle changes and/or vaccination” the authors write.

Looking at the increasing incidences of various types of cancers, including lung cancer, the authors concluded that “large risk proportions for cancer are attributable to changing environments” such as smoking and air pollutants. Exposure to the sun and poor diet play a role.

This has been widely known among scientists, and might sound like the advice you hear from your doctor. But what this study does is build upon a conversation about how cancer starts and why there is some variability in the kinds of cancers.

Earlier this year a study that ran in the journal Science set off a public health debate when media interpretations of the work concluded that many of the cancers were due to “bad luck.” In fact, the authors of that paper Dr. Bert Vogelstein, a prominent geneticist, and biostatistician Cristian Tomasetti said they were merely talking about variety in cancers in 31 different tissue types.

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Vogelstein and Tomasetti believed some of the variation — for example, why there were more instances of colon cancer than brain cancer — may be in part due to random mutations that came up during DNA replication in normal, noncancerous stem cells, the study said. That means some people develop cancers because of “bad luck” at the cellular level, they said in the paper.

The authors of that study said that did not give people license to start smoking or start using tanning beds. Essentially, the authors wanted researchers to take this factor into consideration when they do more research to figure out how to fight cancer.

What may have contributed to some of the misinterpretation was a typographical error in the last sentence of the work that said “primary prevention measures are not likely to be effective” for 22 cancers including melanoma.

Tomasetti said they actually said that “primary prevention measures are not ‘as’ likely to be effective.” Without the word “as,” the meaning of the sentence changed. It has since been corrected in the online version of the story.

The World Health Organization’s International Agency for Research on Cancer issued a press release at the time that said the agency “strongly disagrees” with the conclusion of the report. It said “concluding that ‘bad luck’ is the major cause of cancer would be misleading and may detract from efforts to identify the causes of the disease and effectively prevent it.” Nearly half of cancers, the agency argued, could be prevented if people changed their lifestyle or reduced their environmental exposure to cancer-causing agents.

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In building on the numbers from the earlier study, this latest research used four different approaches to estimate the causes of cancer. Their work including computer models, genetic evaluation and population data to conclude that only 10% to 30% of cancers started because of this “bad luck” factor. The greater majority of cancer might be due to outside factors. Co-author Dr. Yusuf Hannunwho is the Director of the Stony Brook University Cancer Center said this is still early-stage work.

“We all advocate strongly for much more research how cancer starts and we want to know more about what are the risk factors and how do they work,” Hannun said.

Bottom line: If you smoke or are overweight or use a tanning bed, you worsen your odds of getting cancer. You can do a lot to reduce your cancer risk, and you can’t just blame “bad luck” for getting sick, but keep in mind “bad luck” at a cellular level can play a role too.