Taller people are at higher risk for cancer, because their bodies contain more cells in which problems can arise, new research suggests. In the past, studies have shown a link between height and cancer risk, and the new study by California researchers suggests it’s due to a simple principle of how cancer develops, according to The Guardian. The researchers found increased risk from height associated with 18 out of 23 types of cancer, and found that each 4 inches (10.16 cm) above average height increases cancer risk by as much as 12 percent.
“Whether that comes from a better diet or the fact that your parents happen to be tall doesn’t matter … it is purely a number of cells, however that comes about,” says Leonard Nunney, a University of California Riverside biology professor, who led the research.
Conversely, certain types of dwarfism were associated with lower cancer risk.
A growth hormone, called IGF-1, may also have a role in triggering cancer in some cases. The hormone speeds up cell division, increasing the likelihood that cancer will develop in the process. This factor may account for why height was found to have a closer association with some forms of cancer, such as melanoma.
To explain the link between height and cancer, prior theories had focused more heavily on the role of these hormones, or on environmental factors early in life such as nutrition or illness. Now, Nunney’s work suggests the number of cells is the main factor.
The study was published in the journal Proceedings of the Royal Society B. In it, Nunney compared his predictions, calculated based simply on the number of cells in the body, with real world figures on cancer rates associated with different heights. This included data sets from Austria, Korea, Norway, and Sweden.
He found his predictions were consistent with the cancer rates. He estimated that women would see a 13 percent increase for every 10 cm above average height, with 12 percent higher risk apparent in real-world observations. For men, he predicted an 11 percent increase, with the actual cancer figures showing 9 percent higher risk.
Some cancers showed no increased risk with height, which Nunney suggested was due to other factors eclipsing the impact of height – such as the role HPV plays in cervical cancer risk.
Georgina Hill, of Cancer Research UK, acknowledged the study helps explain earlier findings linking height and cancer risk, but points out that the risk is minor compared with those involved in lifestyle choices. She notes that “there’s plenty you can do to reduce the risk of developing cancer, such as not smoking and keeping a healthy weight.”