(CNN) – While many people try to eat healthy and exercise, a recent study suggests that it may not keep you cancer free.
A Johns Hopkins Medicine research study indicated that bad luck is the primary cause of most cancer cases.
Two scientists who ran statistics on cancer cases say two-thirds of cancers in adults can be attributed to random mutations in genes.
Dr. Otis Brawley, chief medical officer for the American Cancer Society, told CNN the study was “good science” that backed up what many scientists already thought.
“This is actually just confirmation of something that we have known for probably 20 years,” he said. “As we have learned more and more about cancer … we’ve come to realize that a number of cancers start purely because of mutations that happen that are just unexplainable. Bad luck is, unfortunately, the right way to explain it.”
However, they say it is still important to stop smoking and to use sunblock.
Of the 31 types of cancer they looked at, 22 were basically “bad luck” cancers.
Some forms of cancer are exceptions, meaning lifestyle and environmental factors play a big role in the disease.
Lung and skin cancer are two of those exceptions.
Also, some cancers are more strongly influenced by genetics than others.
“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,” said cancer researcher Bert Vogelstein.
An unhealthy lifestyle can play a bigger role with certain cancers than others.
“Changing our lifestyle and habits will be a huge help in preventing certain cancers, but this may not be as effective for a variety of others,” medical statistician Cristian Tomasetti said.
Dr. Brawley says people should not alter behaviors that are shown to lessen the risk of cancer, including not smoking, managing their weight and exercising.