Taller people are more susceptible to cancer

Taller people are more susceptible to cancer

Core Tip: Large studies have shown that higher people are more likely to develop cancer than shorter people. So far, it is not clear whether this increased risk of cancer is a direct consequence of more cells or other factors in the body. In a new study, Leonard Nunne, an evolutionary biologist at the University of California, Riverside, used data from thousands of people to confirm that height itself has a direct impact on the risk of multiple cancers.

Large studies have shown that taller people are more likely to develop cancer than shorter people. So far, it is not clear whether this increased risk of cancer is a direct consequence of more cells or other factors in the body. In a new study, Leonard Nunne, an evolutionary biologist at the University of California, Riverside, used data from thousands of people to confirm that height itself has a direct impact on the risk of multiple cancers.

Joshua Schiffman, a pediatric oncologist at the University of Utah who was not involved in the study, said, "This is a very exciting paper that does record what we have discussed for a long time in this field but never really measured accurately." He added that it "confirms that the more cells in a human body, the more cells divide and the more likely cancer is to develop". "Even if the ultimate risk is very small, it will have a broader impact on the field of comparative oncology and try to understand... the natural defense of cancer by looking at nature."

A widely accepted view of cancer production is that during a single cell's lifetime, it gradually accumulates a set of mutations, leading to uncontrolled division. Consistent with this hypothesis, one hypothesis is that the more cells there are in an organism, the more likely they are to produce these cancer-initiating mutations.

People may expect that humans are much older and live longer than mice, so they should have a higher incidence of cancer. However, it seems that no larger animal species suffers more cancer than the smaller ones, which is also a logical problem described by Richard Peto, an epidemiologist at Oxford University in 1977.

Scientists have theoretically pointed out that larger animals can solve the problem of having more cells by evolving more ways to suppress cancer, such as elephants. Pachyderm has at least 20 copies of the gene encoding tumor suppressor protein p53, while humans have only one copy. But in the same species, there are only more cells, and larger individuals still have a greater risk of cancer than smaller individuals, Nunney said, a view that has been confirmed by reports of cancer incidence in humans.

One possible explanation supported by some cancer biologists for these differences among individuals is that factors that make people taller also increase cancer risk, but higher height and more cells do not directly lead to more cancer. In this new study, Nunney began to study which hypothesis is more suitable for existing data.

He used a simple quantitative model to predict what cancer incidence would be if the number of cells was the cause of the change in the number of cancer cases in a species based on height estimates. He then used data from several previous large-scale studies around the world (four for women and three for men, each tracking at least 10,000 cancer cases) to compare predicted cancer incidence with actual cancer incidence.

Nunney's quantitative model predicts that an increase of 10 centimeters in height will increase the overall cancer risk by about 10%. This is what epidemiological surveys have observed: for women, a 10 centimeter increase in height increases the risk of cancer by about 12%, while for men, the figure is 9%.

Michael Hochberg, an evolutionary biologist at the University of Montpellier in France who was not involved in the study, said: "The main message of this study is that the impact is minimal. Although the impact is real, the greater impact on cancer risk is our lifestyle. Thirty to sixty percent of cancers are caused by this. This is something that people can control.

In order to take a comprehensive and fair view of this increased cancer risk, if the lifetime risk of cancer is 38% for the average height person, then the risk of cancer increases by 10% for the person whose height increases by 10 centimeters, which means that the absolute risk is now about 42%.

Nunney also found abnormal values in specific cancer types. Cervical and oral cancers, for example, do not seem to be closely related to height, he wrote in his paper, which may be explained by established environmental causes - human papillomavirus (HPV) infection and smoking.

On the other hand, there is a strong correlation between the incidence of melanoma and other skin cancers and height: an increase of 10 centimeters in height is associated with an increase in the risk of these cancers by more than 20%. Nunney told Scientist that one possible explanation for this strong correlation comes from limited evidence that "taller people have higher levels of circulating insulin-like growth factor-1 (IGF-1)" and there are some indirect signs that it does induce slightly faster refinement. Cell division. He adds, "The reason why melanoma seems to be strongly associated with height may be that people of higher stature may lead to a slight increase in cell division in skin cells." He acknowledged that there was not much data to support this view, which provided an opportunity for future research.

According to Van Savage, an evolutionary biologist at the University of California, Los Angeles, who was not involved in the study, another open question is how metabolic rates affect the increased risk of cancer associated with height. "On average, taller people have lower metabolic rates per cell," he said, and in general, the bigger animals, the lower metabolic rates per cell. Savage adds that in the future it will be necessary to explore whether some of the effects of height are offset by potentially beneficial declines in metabolic rates.

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