Living a healthy lifestyle doesn't always protect you from cancer -- it can still occur when cells mutate. Scientists at Johns Hopkins University say two-thirds of all cancers are random.
“Random mutations that occur as normal cells divide,” says lead researcher Dr. Cristian Tomasetti. “They will happen no matter what. In some cases, that's enough to cause cancer.”
Tomasetti says smoking and other factors can be blamed for most lung cancers, but pancreatic cancer is different.
“Seventy-seven-percent is due, in fact, to random mutations,” Tomasetti says, “only 18 percent due to environmental factors.”
He says some other cancers are totally unavoidable.
“Brain or prostate or bone cancer,” he says, “actually the random component accounts for 95 or more percent.”
The doctors say their results emphasize the need for checkups so cancers can be detected early.