THURSDAY, July 25 (HealthDay News) -- Sizing up cancer risk after menopause, scientists say taller women may face higher odds of developing a malignancy than their shorter peers.
For every height increase of roughly 4 inches, older women faced a 13 percent greater overall risk for 19 types of cancer, a new study suggested. When broken down by specific type, risk rose almost one-third for certain cancers.
"At this point there have been enough studies that have pointed in the same direction for us to be reasonably certain that among these women there is an increased risk for cancer with increasing height," said study co-author Dr. Thomas Rohan, chairman of the department of epidemiology and population health at the Albert Einstein College of Medicine in New York City.
"Although it's a very interesting observation, we don't really know what explains this," Rohan said. "Maybe it's greater organ size or changes in certain hormone levels."
However, since the findings only suggest an association and do not prove a direct cause-and-effect relationship between height and cancer risk, lanky women shouldn't panic.
For the study, published in the August issue of the journal Cancer Epidemiology, Biomarkers & Prevention, the authors sifted through data previously collected by the Women's Health Initiative. That effort involved nearly 145,000 women who were between 50 and 70 years old when recruited for the study during the 1990s.
The study authors focused on a subset of nearly 21,000 postmenopausal women who had developed at least one form of cancer during a 12-year follow-up period.
After considering a patient's age, drinking and smoking history, educational background, weight and body-mass index, and the use of hormone replacement therapy, the researchers concluded that increased height seemed to be independently linked to an increased risk for cancer.
The association held up even after accounting for each patient's history of undergoing cancer screenings, including mammograms, Pap smears and colorectal exams.
Breast, colon, endometrium, kidney, ovary, rectum and thyroid cancer risk all rose with height, the research team said, as did various forms of myeloma and melanoma.
Specifically, with each additional 10 centimeters (about 4 inches) of height, the odds of developing melanoma, breast, ovary, endometrium or colon cancer rose 13 percent, to 17 percent. And the risk of kidney, rectum, thyroid or blood cancers grew 23 percent, to 29 percent, the study authors said.
How the height-risk observation might play out in terms of improving cancer screening and intervention remains to be seen, Rohan said.
"It's probably not an effective screening mechanism. My gut is that it is just too broad a factor to be useful," he said. "And clearly we're not talking about a modifiable factor. Obviously we're not recommending that women do what they can to reduce their height. But with more work this may ultimately tell us something about the biology of cancer, and how genetics plays a role in raising cancer risk among some women and men."
Rebecca Siegel, an epidemiologist and director of surveillance information at the American Cancer Society, said the findings open multiple avenues for further consideration.
"One possible explanation for these findings is that early developmental exposures that influence adult height may also contribute to cancer risk," she said. "In which case height would be a marker for cancer risk and not a causal factor." Childhood nutrition, for instance, influences adult height.
It's possible that taller people simply have a larger number of cells, Siegel added. "While the underlying reasons for this association are not well understood, this information may be an important piece of the cancer puzzle that could contribute to the further understanding of how and why cancer develops," she said.
For more on cancer causes and risk factors, visit the U.S. National Cancer Institute.
SOURCES: Thomas Rohan, M.D., Ph.D., chairman and professor of epidemiology and population health, Albert Einstein College of Medicine, Yeshiva University, New York City; Rebecca Siegel, M.P.H., epidemiologist, and director of surveillance information, American Cancer Society, Atlanta; August 2013 Cancer Epidemiology, Biomarkers & Prevention
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