Cancer Risk May Increase With Height For A Simple Reason

January 30, 2021

A new study has found that the taller you are, the greater your risk of cancer may be.

The idea that there might be a link between height and cancer risk has surrounded since the 1950s, according to study author Leonard Nunney, an evolutionary biologist at the University of California, Riverside. So he decided to investigate.

For the study, published Oct. 24 in the journal Proceedings of the Royal Society B, Nunney analyzed data from four large-scale studies, totaling hundreds of thousands of cancer patients. He found that for every 10 centimeters (4 inches) increase in height, there was a 10 percent increase in cancer risk.

However, instead of proving that height increases cancer risk, the study found an association between height and cancer risk.

However, there may be a fairly simple explanation for the link between height and cancer risk. Taller people have more cells in their bodies, Nunney told Live Science.

Cancer is the result of mutations in the DNA of individual cells, Nunney said. One way these mutations occur is when cells in the body divide, which happens numerous times in a person’s lifetime. Some of these mutations are harmless, but others cause the cells to divide out of control.The more cells there are, the higher the mutation rate, and the higher the chance that one of these mutations will lead to cancer, Nunney said.

The study looked at 23 cancers in both men and women and found a strong correlation between height and the risk of 14 cancers. However, for some cancers – particularly those of the pancreas, esophagus, stomach and mouth – the study found no link between height and risk.

“We can only speculate” as to why the risk of these four cancers is not linked to height, Nunney said.” The types of cancers we don’t see a clear link to height have traditionally been associated with significant environmental influences.” Oral cancer, for example, is linked to factors including alcohol consumption and smoking.

Nunney says he would generally expect to see similar effects on cancer risk, regardless of which organ the cancer starts in, because taller people tend to have larger organs and therefore consist of more cells. (Obesity, on the other hand, doesn’t increase the number of cells in the body, but rather makes some cells larger, he added.)

The study found that for thyroid and skin cancers, height appears to be a stronger risk factor than it is for other types of cancer. And for thyroid cancer, for example, other variables, such as gender and nationality, also played a role. The study found that taller Korean women were more likely to develop thyroid cancer than shorter men and women of other nationalities.Nunney said that people with higher levels of the growth hormone IGF-1 may have a higher risk of skin cancer.

“Previous studies have shown that taller people tend to have higher IGF-1 levels,” Nunney said.” And there’s data suggesting that having higher IGF-1 levels in adulthood leads to faster cell division.”

Humans aren’t the only animals where body size and cancer risk may be correlated, Nunney said. For example, larger dog breeds tend to be more susceptible to cancer than smaller dogs.

However, this effect doesn’t translate among animal species, Nunney says; in other words, whales aren’t more likely to get cancer than rats. In fact, larger species, such as whales and elephants, seem to live longer and are less likely to develop cancer than smaller animals. And that, Nunney says, gives humans something to study.

“It seems that, over the course of evolution, large animals have developed additional layers of cancer suppression,” Nunney said.” If we find out how these extra layers work, we may be able to take advantage of that.”