Just like winning the lottery, whether you look like a supermodel, or can slam dunk like LeBron James, your chances of developing cancer at some point in your life may be due to sheer luck, according to a study published in Science.
In their research, Christian Tomasetti and Bert Vogelstein, both from Johns Hopkins University, say that nearly two-thirds of cancers may not be the result of genetics or the environment, but rather "the stochastic effects associated with the lifetime number of stem cell divisions within each tissue." The mutations in the stem cells are not preventable, and "these stochastic influences are, in fact, the major contributors to cancer overall, often more important than either hereditary or external environmental factors" they add.
Tomasetti and Vogelstein searched through the literature and identified 31 tissue types for which stem cells had been quantitatively assessed. They compared the number of cell divisions in the 31 tissue types with the overall incidence of cancer inAmericaand determined that 65 percent of the cancer risks among the different tissues could be explained by the total number of stem cell divisions in the tissues.
"Thus, the stochastic effects of DNA replication appear to be the major contributor to cancer in humans," they say.
Before you smoke that extra cigarette while working on your tan, however, it's good to keep in mind that one-third of cancers may be tied to environmental or genetic factors. The types of cancer for which the environment can play a major role include lung and skin cancer, while cancer types for which stem cell mutations, and thus bad luck, appear to be the main driver include brain and ovarian cancer, and leukemia, according to the Science article.
The researchers say that their work could have a major impact on public health, including efforts aimed at preventing cancer. Primary prevention methods, such as vaccines against infectious agents, or changes to lifestyle, would have little effect on the 65 percent of cancers for which genetics and environment play only a minor role in their development. For these cancers, measures such as early detection, should be the main focus of prevention, the researchers say.