Most cancer-causing mutations are just really bad luck, according to new research.
Researchers from Johns Hopkins Kimmel Cancer Center say two-thirds of mutations in human cancer are caused by naturally occurring changes within the cell.
Those mutations occur when a cell replicates itself. The process isn't perfect, and sometimes, errors occur while DNA is being copied.
But those mutations don't always result in cancer, and they can even be beneficial to an organism.
The study's results do not apply to all kinds of cancer equally. Environmental factors, like smoking, are still the main cause of lung cancer.