The Strange Mystery of the Cancer Anomaly

Here’s an interesting puzzle. The common conception is that your risk of cancer starts off small in early life and increases as you get older. So children and young people are less likely to develop the disease than somebody who is middle aged who in turn is less likely to develop cancer than a centenarian.

Not so. Epidemiologists have long known that the incidence of most cancers increases until it reaches a maximum at a certain age and then drops dramatically as people get older. The anomaly is well studied, found all over the world and true for many different types of cancer (see diagrams above).

That raises an important question: how come? After all, cancer is thought to start when a series of genetic alterations accumulate in a cell. These changes prevent ordinary cell functions such as DNA repair and so on and these malfunctions eventually trigger cancerous growth. Clearly, if these changes accumulate over time, the risk of developing the disease must also increase over time.

And therein lies the puzzle, one that has stumped oncologists and epidemiologists alike for years. What could possibly explain the discrepancy between the data and this entirely reasonable model of cancer development?

Today, we get an answer thanks to the work of James Brody a biomedical engineer at the University of California, Irvine. He shows that there is no discrepancy between the data and the model of cancer development provided that one additional assumption is true. This is that the population can be divided into two groups—one group that is susceptible to cancer and a much larger group that is not susceptible to cancer.

by Physics arXiv Blog |  Read more:

Image: uncredited