While sun exposure, smoking and pollution are known cancer catalysts, researchers at Johns Hopkins Medicine have found that the vast majority of cancers stem from random genetic mutations.

“All cancers are caused by a combination of bad luck, the environment and heredity,” says team member Bert Vogelstein. “We’ve created a model that may help quantify how much of these three factors contribute to cancer development.”

Using this model, these experts found that 65 percent of cancer instances can be attributed to cell division. The official statement announcing the research asserts that cancerous tissue forms when the chemical makeup of a cell’s DNA is swapped for another during the cell replication process.

When the mutated cells are produced in greater numbers and pile upon one another, the more advanced side effects of the illness emerge.

“Cancer-free longevity in people exposed to cancer-causing agents, such as tobacco, is often attributed to their ‘good genes,’ but the truth is that most of them simply had good luck,” explains Vogelstein.

However, smoking and sun-bathing will still increase the odds of cancer forming, undercutting the random benefit of good luck.

While cancer research has made strides in recent generations, “the actual contribution of these random mistakes to cancer incidence, in comparison to the contribution of hereditary or environmental factors, was not previously known,” according to Vogelstein.

This research appears to correlate with the higher incidence of cancer in areas of the body that show faster rates of cell division. The authors point toward the accelerated rate of colon cell replication, that reportedly triggers a higher prevalence of cancer than the small intestine, lined with a slowly dividing tissue type.

“This study shows that you can add to your risk of getting cancers by smoking and other poor lifestyle factors,” adds Vogelstein. “However, many forms of cancer are largely due to the bad luck of acquiring a mutation in a cancer driver gene regardless of lifestyle and hereditary factors. The best way to eradicate these cancers will be through early detection, when they are still curable by surgery.”

The study was originally published in the peer-reviewed magazine Science.