(CNN) Tall people are at a greater risk of cancer because they have more cells in their body, new research has suggested. 
 
 A person's risk of developing cancer increases by 10% for every 10 centimeters (4 inches) they are over the average height, the study said, because they have more cells which could mutate and lead to cancer. 
 
 Average height was defined in the study as 162cm (5 feet, 4 inches) for women and 175cm (5 feet, 9 inches) for men. 
 
 The findings match with previous research, which has also connected height to an increased risk of developing a range of health problems including blood clots, heart problems and diabetes. 
 
 Leonard Nunney, a professor of biology at the University of California Riverside, analyzed previous sets of data on people who had contracted cancer -- each of which included more than 10,000 cases for both men and women -- and compared the figures with anticipated rates based on their height. 
 
 He tested the hypothesis that this was due to the number of cells against alternatives, such as possible hormonal differences in taller people, which could lead to an increased rate of cell division. 
 
 A link was found between a person's total cell number and their likelihood of contracting cancer in 18 of the 23 cancers tested for, the study says. 
 
 The research also found that the increase in risk is greater for women, with taller women 12% more likely to contract cancer and taller men 9% more likely to do so. Those findings matched with Nunney's predicted rates, using his models, of 13% for women and 11% for men. 
 
 Colon and kidney cancer and lymphoma were among the types of cancer for which the correlation was strongest. 
 
 "We've known that there is a link between cancer risk and height for quite a long time -- the taller someone is, the higher the cancer risk," Georgina Hill from Cancer Research UK told CNN. 
 
 "What we haven't been sure of is why -- whether this is simply because a taller person has more cells in their body, or whether there's an indirect link, such as something to do with nutrition and childhood," added Hill, who was not involved in the study. 
 
 She said the study provides good evidence of the "direct effect" theory that the total number of cells does indeed cause the link. 
 
 "The methodology is good - they took data from large studies, which is important, and they looked at lots of different categories of cancer." 
 
 But she noted that the increase in risk of developing cancer is small compared to the effects that lifestyle changes can have. 
 
 "It was only a slightly higher risk and that there are more important actions that people can take to make positive changes, [such as] stopping smoking and maintaining a healthy weight," she said. 
 
 Two of the types of cancer tested for, thyroid cancer and melanoma, were found to be more susceptible to an increase in risk than expected, and Nunney suggested in the study that other factors could be at play in those cases, such as geography. 
 
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 "There are no obvious reasons for these exceptions, although the author speculates that cell turnover rates may come into play for melanoma," Dorothy C. Bennett, director of the Molecular and Clinical Sciences Research Institute in London told CNN. Bennett, who was not involved in the study, explained that pigment cells, the source of melanoma, divide and are replaced a little faster in taller people. 
 
 "But I cannot at present think of any reason why this [faster division] should be so, but nor any other clear reason for the higher correlation with height," Bennett said. ||||| Size really does seem to matter when it comes to cancer risk. 
 
 Being tall undoubtedly has its benefits. You can see in a crowd and grab objects off high shelves. 
 
 But with the good comes the bad. The taller you are, the higher your odds of developing cancer, and a new paper has added weight to this. 
 
 key points Key points: Taller people have more cells in their body, as well as higher levels of a protein that encourages cells to divide and grow 
 
 For every 10cm over the average height, a person's risk for cancer increases 10 per cent 
 
 New analysis of data from big cancer studies supports this, and also finds a few specific cancers to be more or less strongly correlated with height 
 
 Leonard Nunney, an evolutionary biologist at the University of California, Riverside, looked at massive cancer databases to find out how the number of cells in a person's body, using height as a proxy, might affect their risk of developing cancer. 
 
 Reporting in the Proceedings of the Royal Society B, he found being taller and having more cells did mean more cancer overall: For every 10 centimetres over the average height, the risk of developing any cancer increased by around 10 per cent. 
 
 This fits with previous studies. 
 
 "If you were comparing a 5-foot guy to a basketball player who's over 7 feet tall, then that basketball player has around twice the risk of cancer across the board," Professor Nunney said. 
 
 He also found that taller people were at much higher risk of melanoma, and women specifically had greater odds of developing thyroid cancer. But it doesn't mean tall people should panic. 
 
 "Now, you can't do anything about your height, but what you can do is tell extremely tall individuals that they should be aware of this, and if they have any concerns, to get checked," he said. 
 
 "It just suggests more vigilance, I think." 
 
 So more cells = more cancer? Sort of 
 
 Whether you grow up towering over your peers or knee-high to a grasshopper depends on a whole host of things, said Yash Chhabra, a cancer biologist at the University of Queensland who wasn't involved with the study. 
 
 "With height, it's not just your genetics that decide how tall a person will be, but also the nutrition that your mother had while they were pregnant," Dr Chhabra said. 
 
 "And, of course, diet and lifestyle as you grow up also have a huge impact on your height." 
 
 key points Peto's paradox If animals with more cells get more cancer, why do humans get more cancer than elephants and whales? 
 
 This is Peto's paradox, named after an Oxford epidemiologist who noticed the phenomenon in the 1970s 
 
 Evolutionary biologists think that more massive species have evolved measures that suppress cancers 
 
 The link between height and cancer risk was brought to light by massive cancer projects, such as the UK's Million Women study. 
 
 "They all demonstrated really clearly that height is indeed a factor," Professor Nunney said. 
 
 "And it's not just one cancer. It's most cancers that have some relationship with height." 
 
 So what's behind this? 
 
 One theory is that taller people simply have more cells. And with more cells comes more chances for cancer. 
 
 This is what Professor Nunney wanted to explore. So he examined Million Women data with three other big cancer projects — one each from the US, Europe and Korea — to see how different types of cancer correlated with height. 
 
 He found most cancer types did increase with height as expected. But there were a few that bucked the trend. 
 
 Environmental effects can mask height effects 
 
 Risk of stomach, mouth and, in women, cervical cancer didn't seem to be affected by height. 
 
 Professor Nunney suspected those cancer types had a "pretty strong environmental influence that might be masking height effects. 
 
 "The easiest one to explain in that sense is cervical cancer, because we know that almost 100 per cent of cervical cancers are related to infection with one of a few strains of HPV." 
 
 What had him stumped, though, was the relatively much higher risk of thyroid cancer in taller women he saw. 
 
 "I have no idea what's going on there," Professor Nunney said. 
 
 "The high value is driven primarily by the data from Korea, where there's a really strong effect with height, especially in women, way higher than you see in other studies. 
 
 "Across other cancers, there's no real geographical variation." 
 
 Taller people — both men and women, in all datasets — tended to have a higher risk of melanoma too. 
 
 With height usually comes more skin. That extra surface area might seem like an easy explanation for more melanoma, but that's not the case, Professor Nunney said. 
 
 Some organs don't scale as much as others. For instance, a taller person might have a larger colon than a shorter person, but each brain will be closer in size. 
 
 "Short people tend to have relatively larger heads than tall people," Professor Nunney said. 
 
 Skin is one of those organs that doesn't scale as much. His predicted melanoma risk for taller people fell well short of the real values. 
 
 Share The reason that big dogs grow so large also increases their cancer risk. 
 
 Growth factors play a role in cancer risk 
 
 This brings us to another potential driver behind the cancer-and-height link: a protein called insulin-like growth factor 1, or IGF-1. 
 
 IGF-1 is produced in response to growth hormone and encourages cells to divide and grow. 
 
 Not surprisingly, IGF-1 plays an enormous role in childhood growth — particularly during puberty — but also helps build up organs and tissues in adults. 
 
 And it turns out that taller people have slightly higher levels of IGF-1 in their blood, so "it may be that tall individuals have just a fractionally faster rate of cell division that could account for the extra cancer", Professor Nunney said. 
 
 And on the flip side, having no IGF-1 appears to bestow anti-cancer qualities. 
 
 A remote population of dwarf people in Ecuador has a mutation in the growth hormone receptor, which prevents the release of IGF-1, said Andrew Brooks, also a cancer biologist at the University of Queensland and not involved with the study. 
 
 "And they don't seem to have any cancer, which is interesting." 
 
 When biologists selectively induce a similar genetic defect in mice, he added, those mice are also "extremely resistant" to developing cancer. 
 
 It's also thought that IGF-1 is why smaller dogs, which usually have lower levels of IGF-1, tend to live longer than their larger counterparts. 
 
 The take-home, though, is that height is far from the be all and end all when it comes to cancer risk, Professor Brooks said. 
 
 Everyone, regardless of their height, can reduce their cancer odds by eating well, exercising, staying away from smoking and being careful in the sun. 
 
 "Smoking, for instance, is a far greater risk than being tall." ||||| Report suggests link between height and cancer risk could simply be because there are more cells for something to go wrong in 
 
 Taller people have a greater risk of cancer because they are bigger and so have more cells in their bodies in which dangerous mutations can occur, new research has suggested. 
 
 A number of studies have previously found a link between a lofty stature and a greater risk of developing some form of cancer, with research suggesting that for every 10cm of height within the typical range for humans, the risk increases by about 10%. A similar link has also been found in dogs, with bigger breeds having a greater risk of such diseases. 
 
 Scientists have put forward a number of different explanations for this, including that certain growth hormones could play a role in both height and cancer, or that environmental factors such as childhood nutrition or illness could be a factor. 
 
 “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,” said Leonard Nunney, professor of biology at the University of California Riverside. 
 
 But now Nunney says he has crunched the numbers to show it might be down to a simpler matter of size: tall people simply have more cells for something to go wrong in. 
 
 Nunney said his work, published in the Proceedings of the Royal Society B, is based on the fundamental model of how cancer develops, whereby individuals accumulate mutations in their cells (other than sperm or eggs) over their life: if a particular set of mutations arise then a certain cancer will initiate. The theory suggests that having more cells, or more divisions per cell, would therefore increase cancer risk. 
 
 Taller people more likely to get cancer, say researchers Read more 
 
 Nunney compared the overall risk of men and women developing cancer of any type with increasing height, as found from previous studies of large cohorts, with what might be expected from calculations based on the number of cells in a body. 
 
 The results reveal that his predictions are in tune with the real-life observations, giving a 13% increased risk for women for every additional 10cm in height compared with 12% from observations, and an 11% predicted increase in men for every 10cm taller compared with 9% seen in real life. 
 
 Overall, an increased risk with height was seen for 18 out of 23 cancers considered. Nunney says some cancers may have shown no link because the effect of height was masked by other drivers such as HPV infection for cervical cancer. 
 
 Nonetheless, Nunney says the findings suggest sheer number of cells is important. “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 said, although he admits height differences only appear to partly explain why men are at greater risk of many cancers than women. 
 
 The research also threw up some surprises: for example, the skin cancer melanoma shows a much stronger link to height than expected – something Nunney suggests might be down to taller people having slightly higher levels of a growth hormone called IGF-1. 
 
 Nunney said a slight boost in the rate of cell division, as a result of higher levels of IGF-1, might have a stronger effect on these cells than it does in other tissues, possibly because melanoma might need a larger set of mutations to develop than other cancers. 
 
 Taller women more likely to develop cancer Read more 
 
 Prof Dorothy Bennett, director of the Molecular and Clinical Sciences Research Institute at St George’s, University of London, welcomed the research, although she said Nunney’s calculations involved a number of assumptions, including that cancer risk increases in direct proportion to adult height. 
 
 But she said the argument was compelling: “The simplifications seem reasonable, and therefore the main study conclusion is probably going to be the best-supported one available at present: namely that for most cancer types, cell number can predict sufficiently well the numerical relations between height and cancer, with no need to suggest additional factors.” 
 
 That said, Bennett said there was no obvious reason melanoma should have a particularly strong link to height. 
 
 Georgina Hill, from Cancer Research UK, said individuals should not be concerned about their stature. “A number of studies over the years have shown that taller people seem to have a slightly higher risk of cancer,” she said. “But 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.”
– A new study on cancer won't make for pleasant reading for tall people. Consider this quote from lead researcher Leonard Nunney of the University of California Riverside: "If you were comparing a 5-foot guy to a basketball player who's over 7 feet tall, then that basketball player has around twice the risk of cancer across the board," he tells Australia's ABC. Yes, Nunney's study in the Proceedings of the Royal Society B suggests that taller people are at greater risk for cancer. The surprisingly simple reason? They have more cells, and thus more things go can wrong in those cells, explains the Guardian. Specifically, the study found that cancer risk rises by 10% for every 4 inches people are above average height—5 feet 4 for women and 5 feet 9 for men, reports CNN. The findings held true for 18 of 23 cancers studied. "Now, you can't do anything about your height, but what you can do is tell extremely tall individuals that they should be aware of this, and if they have any concerns, to get checked," says Nunney. Cancers of the colon and kidney were among those with the strongest correlation to height. A researcher not involved with the study says it backs up previously seen links between height and cancer, but she said tall people shouldn't worry too much. "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," says Georgina Hill of Cancer Research UK. (A WWE wrestling star made an emotional revelation about his own cancer.)