July 21st, 2011
12:47 PM ET
The taller a woman is, the greater her risk of developing one of 10 different cancers, according to a new study published in the journal Lancet.
Researchers followed 1.3 million middle-aged women in the United Kingdom for several years, and found the risk of cancer increased by about 16% for every 4 inches or 10 centimeters of increased height.
But the question remains, why?
According to Jane Green, a clinical epidemiologist at Oxford University and the lead author of the study, the tallest group – women 5 feet 9 or taller – were 37% more likely to develop cancer than the shortest group – women 5 feet and shorter- regardless of factors such as age, socioeconomic status, body-mass index and amount of physical activity.
There were 97,376 incidents of cancers reported among the women, and height related increases were greatest for the following: colon, malignant melanoma, breast, endometrial, kidney, central nervous system, non-Hodgkin lymphoma, and leukemia.
The study did not investigate what specifically about height led to the increased risk, but the research add to other studies that have found a link between cancer and height. The study authors aren't sure what exactly increases the cancer risk, but they believe there are several theories that warrant more investigation.
For one, the authors propose that “taller people have more cells, and thus a greater opportunity for mutations leading to malignant transformation.”
Another possible culprit: Hormone levels resulting from insulin-like growth factors both in childhood and in adult life.
“Growth hormones increase cell growth and rate of division, and inhibit cell death,” Green explained in an email. “Both of these might be relevant to cancer either directly or perhaps just by increasing the number of cell divisions during which mutations can occur in the cell DNA.”
A study published earlier this year by researchers in Ecuador found that a condition that stunts the growth of extremely short Ecuadorians, simultaneously reduced the risk of cancer and diabetes in that population. The patients in that study all exhibited a specific mutation in their growth hormone receptor gene.
According to experts with the American Cancer Society, tall people should not be alarmed because of these findings.
"The underlying biological reason for the slightly higher risk among taller people is not known,” explains Eric Jacobs, strategic director of pharmacoepidemiology. “Nobody will be trying to make themselves shorter to lower their cancer risk, and the current results do not mean tall people need additional cancer screening," Jacobs explains.
In fact the study found that smoking was a much stronger risk factor. In current smokers, smoking-related cancers were not as strongly related to height, which Jacobs says highlights the overwhelming importance of the role smoking plays in cancer risk.
"The bottom line is that both short and tall people can lower their risk of developing and dying from cancer by not smoking, maintaining a healthy weight, and getting the recommended cancer screening tests," he says.
The authors also note more research is needed as certain populations continue to grow taller. The average height of people in Europe has increased by about 1 cm (or .39 inch) per decade throughout the 20th century, the study authors say.
According to the Centers for Disease Control, between 1960 and 2002, the average height of an adult man in the U.S.increased from just over 5 feet 8 inches to 5 feet 9 and ½ inches, while the average height of a woman increased from just over 5 feet 3 inches to 5 feet 4.
“The increase in adult height during the past century could thus have resulted in an increase in cancer incidence some 10–15% above that expected,” the authors report.
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