The association between height and cancer has been observed for a long time, with taller people in general being at greater risk of developing the disease. A new study has looked into this link across a massive sample size of more than 5 million adults. Not only were they able to show that the association held over such large numbers, but they also calculated the increased risk for every extra 10 centimeters (4 inches) of height, claim the researchers.
They found that the risk of developing cancer in women increased by 18% for every extra 10 centimeters, while for men the risk rose by 11%. The research was carried out by looking at the military records of 5.5 million people in Sweden, born between 1938 and 1991. But considering that the study has so far only been presented at a conference, and not been published yet, some scientists warn about drawing too many conclusions from the research. Height might be one of many risks for developing cancer, but it is nowhere near as big a risk as well established factors like smoking, obesity or poor diet.
“This observation has been made before in previous studies, and we already knew that breast and prostate cancers can be associated with height,” said The Institute of Cancer Research's Professor Mel Greaves, was not involved in the study, in a statement. “What would be a biologically plausible reason for this association?”
The best theory tends to point the finger at growth hormones, says Greaves. Other studies have shown how people who have genetic dwarfism also have lower rates of cancer compared to the general population. The genetic mutation that makes them shorter is in the part of their DNA that codes for growth hormone receptors on their cells, meaning the cells don’t respond to the hormone in the body. Another piece of research has shown that mice genetically engineered to produce more or less growth hormone also have correspondingly higher and lower rates of cancer in correspondence with their with body size.
This new piece of research has, however, been criticized. As the study is based on previously collected data over a period of decades, the researchers obviously didn’t control for confounding factors, like smoking. It’s also probable that the increases in risk would also change depending on the location of the study, their diets, and exposure to the Sun, among many other things.
“In general, I would caution against interpreting a link as causal – however for height and cancer there is considerable evidence that suggests that the link is not explained by other known factors,” says Dr Jane Green from the University of Oxford. “Clearly, adult height is not itself a 'cause' of cancer, but is thought to be a marker for other factors related to childhood growth.”