Bad Luck is Responsible for Two-Thirds of Cancers Says a New Study

Have you ever wondered why some people can smoke and drink into their old age while others with healthier lifestyles receive a cancer diagnosis? A landmark study from the Johns Hopkins Kimmel Cancer Center explains that random luck plays a significant role in determining whether or not a person is diagnosed with cancer during their lifetime.

Bad luck is responsible for two-thirds of adult cancer while the remaining cases are due to environmental risk factors and inherited genes, say scientists. 

"All cancers are caused by a combination of bad luck, the environment and heredity, and we've created a model that may help quantify how much of these three factors contribute to cancer development. Cancer-free longevity in people is often attributed to their good genes, but the truth is that most of them simply had good luck," said Bert Vogelstein, a scientist at the Johns Hopkins University School of Medicine. 

The study involved comparing stem cell divisions in 31 cancer types. The research team determined which were driven by the 'bad luck' factor of random DNA mutations and which had a higher incidence due to a combination of bad luck and environmental or hereditary risk factors. 

"It was well known that cancer arises when tissue-specific stem cells make random mistakes, or mutations, when one chemical letter in DNA is incorrectly swapped for another during the replication process in cell division. 

The more these mutations accumulate, the higher the risk that cells will grow unchecked, a hallmark of cancer. The actual contribution of these random mistakes to cancer incidence, in comparison to the contribution of hereditary or environmental factors, was not previously known," notes Mr. Bert. 

However, the study did not include breast cancer, which is the most common cancer in women, or prostate cancer, which is the second most common cancer in men after skin cancer. 

"You can add to your risk of getting cancers by smoking or other poor lifestyle habits. However, many forms of cancer are caused largely due to the bad luck of acquiring a mutation in a cancer driver gene regardless of lifestyle and heredity factors," Vogelstein said. 

Co-researcher Cristian Tomasetti observed that the research made a strong case for early detection.  

"If two-thirds of cancer incidence across tissues is explained by random DNA mutations, then changing our lifestyle habits will be a huge help in preventing certain cancers, but this may not be as effective for a variety of others. We should focus more resources on finding ways to detect such cancers at early, curable stages," he said 

Director of public policy at Cancer Council Australia, Paul Grogan, said putting cancer incidence down to "luck" was an oversimplification, noting that the global cancer burden is expected to nearly double to 21.4 million cases and 13.5 million deaths by 2030.  

"Measures including participation in screening and surveillance programs, being vigilant about your health, getting regular check-ups, avoiding risk factors can help us to prevent or survive cancer, irrespective of our genes," Mr. Paul said. 

Director of programs at Cancer Council NSW Kathy Chapman said research into gene mutations would lead to improved cancer treatment and help us understand at that very microscopic level which treatments will lead to the best outcomes. 

"The findings would help us to understand which genes are really the important ones when somebody is diagnosed with cancer," she said. 
 Source:Johns Hopkins University School of Medicine.