A new study suggests that tall people are more likely to get cancers because they have more number of cells that can undergo dangerous mutations.
There have been studies earlier that have linked stature with cancers. Some researchers have suggested that for each 10cm height within the normal stature for humans, the risk of cancers increases by roughly 10 percent. Among dogs too, the bigger and taller breeds are more at risk of cancers than the smaller ones. The biological and plausible reasons behind this association could be the role of growth hormones that allow for increased height as well as contribute to increase risk of cancer. Childhood nutrition and illnesses could also play a role in this association say experts.
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Study leader Leonard Nunney, professor of biology at the University of California Riverside said in a statement, “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.” The results of this new study is published in the latest issue of the Proceedings of the Royal Society B.
According to Nunney individuals from the time they are single celled zygotes to fully grown adults accumulate mutations within their cells. These mutations continue for life. If these mutations are dangerous, cancers may appear. As tall people have more number of cells, the number of cell divisions among them is also more. This could thus increase the cancer risk he explained.
For this study the team of researchers compared overall risk of men and women of getting any type of cancer and analyzed it based on heights. The data was gathered from previous study cohorts from Korea, Norway, Sweden and Austria. The model developed took into account the number of cells of the body. The results showed that there was a 13 percent rise in risk of cancers for women associated with each 10 cm increase in height. The real life value is around 12 percent. For men the predicted rise in risk of cancers is 11 percent from the analysis and 9 percent in reality among the populations.
Among the 23 cancers considered, the rise in risk of the cancers with height was seen in 18 types of cancers, the researchers wrote. The ones that did not show association were for example cervical cancer which is caused by Human Papilloma virus (HPV) infection explained Nunney. Skin cancer melanoma on the other hand shows a remarkable association with height explained Nunney. This could be due to the higher levels of growth hormone called IGF-1 in their bodies he said. IGF-1 can increase rates of cell division. Melanomas typically need larger mutations to develop than other cancers and so IGF-1 could play a role, he said.
The commonest cancers associated with height among women were those of thyroid, skin, colon, lymphomas, ovaries, breast and uterus. For men the commonest cancers linked to height were thyroid, skin, lymphomas, colon, kidneys, biliary tract and the central nervous system. No association of height could be found with cancers such as esophagus, stomach, mouth and cervical cancer among women and stomach cancer among men.
Nunney explained that the number of cells is important adding, “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.” He also added that men are more likely to get cancers than women because of their stature.
According to Georgina Hill, from Cancer Research UK this study should not alarm tall people. She added, “...the increased risk is small and there’s plenty you can do to reduce the risk of developing cancer, such as not smoking and keeping a healthy weight.”