Why are tall people more likely to develop cancer?

The Global Cancer Research Fund reports that there is strong evidence that tall people have a higher chance of developing cancer: pancreas; large intestine; uterus (endometrium); ovary; prostate; kidney; skin (melanoma); and breast (before and after menopause). But why? Here's what we know, don't know, and suspect.

Well-established model

A study of one million women in the UK found that for 15 out of 17 cancer cases they investigated, the taller you are, the more likely you are to develop it. Leonard Noni, a biology professor at the University of California Riverside, analyzed previous sets of data on people who developed cancer — each of which included more than 10,000 cases for both men and women — and compared the numbers to projected rates based on their height. He found this association in 18 of the 23 cancers tested, and the British study found that every ten centimeter increase in height increased the risk of cancer by about 16%. A similar increase has been found in men. The other study was 10% for every 10 centimeters (4 inches), with mean height defined as 162 cm (5 ft 4 in) for women and 175 cm (5 ft 9 in) for men. Let's put that in perspective. If about 45 out of every 10,000 women of medium height (about 165 cm) develop cancer each year, about 52 out of every 10,000 women who are 175 cm tall will develop cancer. That means only seven more cancers. So, it's actually a small increase in risk.

Why?

The relationship between height and cancer risk occurs across ethnicities and income levels, as well as in studies that have looked at genes that predict height. I tested the hypothesis that this is due to the number of cells versus alternatives, such as potential hormonal differences in taller people, which may lead to an increased rate of cell division. The reason is not entirely clear and there are two strong theories. The first is associated with the fact that a taller person will have more cells. For example, a tall person is more likely to have a longer large intestine with more cells and therefore more likely to have cancer of the large intestine than a short person. Scientists believe that cancer develops through the accumulation of damage to genes that can occur in a cell when it divides to form new cells and the more times a cell divides, the more likely it is that genetic damage will occur and pass on to new cells. The more damage accumulated, the more likely it is that cancer will develop. A person who has more cells in their body will have more cell divisions and therefore there is likely to be a higher chance of cancer developing in one of them. Some research supports the idea that having more cells is the reason people develop cancer and may explain to some extent why men are more likely to develop cancer than women (because they are on average taller than women).But research has shown that the increased risk due to height is greater in women, with taller women 12% more likely to develop cancer, while taller men are 9% more likely to develop. However, it's not clear that height is related to the size of all organs (e.g., do taller women have larger breasts or ovaries?). One study tried to evaluate this. The study found that while organ mass explained the relationship between height and cancer in eight of the 15 cancer cases assessed, there were seven other cases in which organ mass did not explain the relationship with height. It is worth noting that this study was very limited due to the amount of data they had on organ mass.

Another theory says that there is a common factor that makes people taller in addition to increasing the risk of cancer. One possibility is a hormone called insulin-like growth factor 1 (IGF-1). This hormone helps children grow and then continues to play an important role in driving cell growth and cell division in adults. This is an important function. Our bodies need to produce new cells when old cells are damaged or age. Some studies have found that people with above-average IGF-1 levels have a higher risk of breast or prostate cancer. But again, this result was not consistent for all types of cancer. The two explanations (more cells and more IGF-1) are likely to play a role. But more research is needed to understand why taller people develop cancer and whether this information can be used to prevent or even cure cancer. "What we haven't confirmed is the cause – whether it's simply because the taller person has more cells in their body, or whether there's an indirect link, like something related to nutrition and childhood," Hill says. She said the study provides good evidence for the "direct effect" theory that the total number of cells actually causes the association. But she noted that the increased risk of cancer is small compared to the effects lifestyle changes can have.

I'm tall. What should I do?

First, remember that height increases your risk of cancer by a very small amount.

Second, there are many things we can all do to reduce the risk of cancer, and these things have a much greater impact on cancer risk than height.

Eat a healthy diet

Exercise regularly

Maintain a healthy weight

If we all do these things, we can significantly reduce the amount of cancer.

You can also participate in cancer screening programs that help detect breast, cervical, and bowel cancers early so that they can be successfully treated.