Postmenopausal women who are taller may be at greater risk for developing cancer, new research reveals.
"We observed a 13 percent increase in risk for all cancers combined for every 10 centimeter (about 4 inches) increase in height," said study researcher Dr. Thomas Rohan, a professor of epidemiolgy and population health at Albert Einstein College of Medicine in New York.
The findings suggest that height was linked with 10 types of cancer in postmenopausal women ages 50 and over, which were melanoma, multiple myeloma (a cancer of the blood), cancers of the breast, ovary, endometrium (uterine lining), thyroid, kidney, and cancers of the colon and rectum (including colorectal cancers).
These results held true even after researchers took into consideration factors known to influence the likelihood of these cancers, including women's age, weight, education, smoking, alcohol consumption and use of hormone therapy for menopausal symptoms.
Broadly speaking, there are two possible explanations for why a person's adult height has an influence on cancer risk, Rohan said. One is genetic factors and the second is early life exposures, such as childhood nutrition and hygiene, both of which can affect adult health, he explained. [10 Do's and Don'ts to Reduce Your Risk of Cancer]
Interestingly, the results showed that more cancer types were associated with height than were linked with body mass index (BMI), or weight, Rohan said.
The findings are published online today (July 25) in the journal Cancer Epidemiology, Biomarkers & Prevention.
Height and cancer risk
In the study, researchers looked at data collected from nearly 145,000 American women ages 50 to 79, who had gone through menopause. The women were all participants in the Women's Health Initiative, a long-term nationwide study designed to better understand the causes of chronic disease in middle-age and older women.
After enrolling in the Women's Health Initiative, participants had their heights and weights measured, and they also completed questionnaires describing their medical history, lifestyle habits and dietary patterns. Over the follow-up period, of 12 years on average, nearly 21,000 cases of cancer were diagnosed among the women.
To evaluate the impact of height on cancer risk in women, researchers looked at the effect of height on the number of cancer cases at 19 different locations on the body.
The biggest increase in cancer risk was seen in cancers of the kidney and blood, with women's risk rising 29 percent for every 10-cm increase in height. Additionally, the researchers found a 13 percent increase in risk for breast or ovarian cancer, a 15 percent increase in melanoma and a 16 percent rise in colon cancer with every 10-cm height increase.
Can't change height
This isn't the first time that researchers have shown a link between greater height and a higher risk for developing cancer at specific sites. Other studies have found that taller men are at increased risk of developing cancer, and previous research in women has found a similar connection in Canadian, British and Asian women.
Rohan said he sees no reason to believe the association wouldn't hold true for some types of cancer in premenopausal women. But because the risk of most cancers increases as people get older, he said that researchers would need data from larger numbers of younger women to observe these trends.
"The association we observed between increasing height and cancer risk is very robust, and there's some consistency with other findings in the scientific literature," Rohan said. What's also new about these results is that researchers looked at 19 different cancer sites in postmenopausal American women, and paid a lot of attention to other confounding factors that can influence cancer risk, especially weight.
Even though height is not a modifiable risk factor for cancer — meaning it's not something an adult can change — the findings are "just an observation," Rohan said. "It has an interesting biological connotation about what might underlie the risk of developing cancer."