Taller people have a greater risk of cancer because they are bigger and so have more cells in their bodies in which dangerous mutations can occur, new research has suggested.
A number of studies have previously found a link between a lofty stature and a greater risk of developing some form of cancer, with research suggesting that for every 10cm of height within the typical range for humans, the risk increases by about 10%. A similar link has also been found in dogs, with bigger breeds having a greater risk of such diseases.
Scientists have put forward a number of different explanations for this, including that certain growth hormones could play a role in both height and cancer, or that environmental factors such as childhood nutrition or illness could be a factor.
One of the major hypotheses was that something was happening early in life that was making your cells more susceptible to cancer and, sort of incidentally, causing you to be tall, said Leonard Nunney, professor of biology at the University of California Riverside.
But now Nunney says he has crunched the numbers to show it might be down to a simpler matter of size: tall people simply have more cells for something to go wrong in.
Nunney said his work, published in the Proceedings of the Royal Society B, is based on the fundamental model of how cancer develops, whereby individuals accumulate mutations in their cells (other than sperm or eggs) over their life: if a particular set of mutations arise then a certain cancer will initiate. The theory suggests that having more cells, or more divisions per cell, would therefore increase cancer risk.
Nunney compared the overall risk of men and women developing cancer of any type with increasing height, as found from previous studies of large cohorts, with what might be expected from calculations based on the number of cells in a body.
The results reveal that his predictions are in tune with the real-life observations, giving a 13% increased risk for women for every additional 10cm in height compared with 12% from observations, and an 11% predicted increase in men for every 10cm taller compared with 9% seen in real life.
Overall, an increased risk with height was seen for 18 out of 23 cancers considered. Nunney says some cancers may have shown no link because the effect of height was masked by other drivers such as HPV infection for cervical cancer.
A rare disadvantage for Chads it seems ---
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