US researchers claim random mutations are responsible for certain cancers


Scientists from US-based Johns Hopkins Kimmel Cancer Centre have developed a statistical model, which measures the proportion of cancer incidence across many tissue types caused by random mutations.

Random mutations occur when stem cells divide.

Johns Hopkins University School of Medicine professor Bert Vogelstein said: "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."

Implications of the model created by the researchers range from altering public perception concerning cancer risk factors to the funding of cancer research.

Johns Hopkins University School of Medicine oncology assistant professor Cristian Tomasetti said: "If two-thirds of cancer incidence across tissues is explained by random DNA mutations that occur when stem cells divide, then 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."

Tomasetti and Vogelstein said they reached the conclusions by searching scientific literature for information on the cumulative total number of divisions of stem cells among 31 tissue types during an average individual's lifetime, under the report on statistical findings published in science.

Using statistical theory, the researchers calculated how much variation in cancer risk can be explained by the number of stem cell divisions, and classified types of cancers they studied into two groups.

Both researchers discovered that 22 cancer types can be largely explained by a "bad luck" factor of random DNA mutations during cell division, while the other nine cancer types had incidences higher than predicted by "bad luck." These were presumably due to a combination of bad luck, as well as environmental or inherited factors.

The scientists also noted that some cancers such as breast and prostate cancer were not included in the report because of their inability to find reliable stem cell division rates in scientific literature.

Funding for the research was provided by Virginia and DK Ludwig Fund for Cancer Research, the Lustgarten Foundation for Pancreatic Cancer Research, the Sol Goldman Pancreatic Cancer Research Center, and the National Institutes of Health's National Cancer Institute.