We all know certain behaviors like smoking can increase your risk of cancer. But can all cancers be linked either to something we did or some factor we inherited?
The surprising answer for many types of cancer appears to be “no” according to a recent article published in the journal Science and reported in The New York Times.
Researchers Dr. Cristian Tomasetti and Dr. Bert Vogelstein of Johns Hopkins University School of Medicine reported that random genetic mistakes or basic bad luck may be responsible for the risk of up to two-thirds of many types of cancer.
That means environmental factors and genetic inheritance may be to blame for only one-third of certain types of cancer cases.
Tomasetti, an applied mathematician, said, “This was definitely beyond my expectations. It’s about double what I would have thought.”
To reach their conclusion, the research team developed a statistical model using known rates of cell division in 31 different types of body tissue. They omitted breast and prostate cancers due to insufficient data on the rate of cell division for those tissue types.
As cells wear out, specialized cells known as stem cells divide to create replacement cells for that specific type of tissue. Stem cells are unique because they are able to divide or replicate themselves many times.
When stem cells divide, they duplicate their own genetic code to create a new cell. Mistakes in the code duplication process can cause uncontrolled growth of those cells, resulting in cancer or a tumor.
The researchers used recently available advances in stem-cell biology to investigate observations made more than 100 years ago that had never been fully explained. Historically, scientists knew that some types of body tissue are at much higher risk to develop cancer than other types of tissue. But they didn’t know why.
For example, cancer is 24 percent more likely to develop in cells in the large intestine than in the small intestine.
The Johns Hopkins researchers determined that large intestine tissue contains many more stem cells than small intestine tissue.