A paper published last week in the journal Science caused the world to reevaluate long-held views on cancer.
A mathematician and cancer geneticist presented an elegant and thought provoking analysis that may require revision of the reigning hypothesis of the past forty years, that most cancers are primarily due to mutations which are either inherited or caused by environmental exposures, such as smoking or certain viruses.
The two authors of the paper analyzed the frequency at which cancer occurs in different tissues throughout the body varies dramatically.
The authors suggested that some proportion of cancers were due simply to random errors that occur during cell division when DNA is copied. They also reasoned that since stem cells are much longer-lived than the majority of cells making up an organ, it is mutations in stem cells that are most likely to contribute to cancer.
After gathering and plotting the most reliable information available from previous research on stem cell number and divisions for 31 different tissues, a surprising correlation was discovered. As the number of stem cell division increased, so did the frequency of a particular cancer.
Each type of cancer was then ranked according to an “extra risk score” which was obtained by multiplying the number of stem cell divisions by the lifetime risk.
What the analysis suggests is that two-thirds of cancers may be due to bad luck rather than to hereditary and environmental factors. This theory turns the conventional theory of cancer on its head.
The major implication of this theory is that a large number of cancers are not likely to be preventable, greater efforts need to be directed at early detection so that cancers can be caught early and treated when treatment is likely to be more effective.
Some believe that this new theory can reassure patients that they are not to blame for their cancer.
