Women's Height Linked to Cancer Risk

Every 4-inch increase in height raises cancer risk 16 percent, study finds.

ByABC News
July 20, 2011, 11:11 AM

July 21, 2011— -- Taller women have a higher risk of developing 10 different cancers, researchers reported today.

A British study of more than 1 million women found that every 4-inch increase in height corresponded to a 16 percent hike in cancer risk.

The finding offers little comfort for tall women, whose height -- guided by genes, nutrition and other environmental influences -- was established in their 20s. But it could shed light on a common cancer-causing mechanism.

"The importance of this research is in understanding how cancers develop," said Jane Green, a cancer epidemiologist at the University of Oxford in the U.K and lead author of the study published Wednesday in Lancet Oncology. "Because height is linked to a wide range of cancers in a wide range of people, it may give us a clue to basic common mechanisms for cancer."

The study focused on women who enrolled in a national breast screening program. But Green said similar results have been reported in men.

Out of 17 different cancers studied, height was implicated in 10, including breast cancer, skin cancer and leukemia. The strongest association was seen in colon cancer, where every 4-inch increase in height corresponded to a 25 percent increased in cancer risk.

The association held up even when other factors known to contribute to cancer risk, such as smoking, were ruled out. However, the link between height and cancer risk was weaker for smoking-related cancers, the authors noted.

Previous studies have linked height to the risk for specific cancers in both men and women. But this is the first to find an association across multiple cancers.

"The similarity of the height-associated [relative risk] for different cancers and in different populations suggests that a basic common mechanism, possibly acting in early life, might be involved," Green and colleagues reported.

The average woman in the U.S. stands about 5-foot-3 -- a height that has increased by up to 0.4 inches per decade over the last century, according to some estimates.

But experts caution that taller women should not worry any more, nor should shorter women worry any less, about their cancer risk.

"The primary value of this study is that it provides us with clues about the importance of possible early life exposures and about the biology of cancer development," said Bruce Trock, professor of urology, epidemiology, oncology and environmental health sciences at Johns Hopkins School of Medicine in Baltimore. "It is not evidence that should cause women or girls to change their behaviors."

"Parents should not withhold food from their children to stunt their growth for cancer risk reduction," said Dr. Tim Byers, associate director for Cancer Prevention and Control at the University of Colorado Cancer Center in Denver.

Byers added that taller women don't need more mammograms or colonoscopies, and shorter women shouldn't use their stature as an excuse to skip screening tests.

Experts stressed that the absolute risk of cancer is still small, even with the height-associated increase. And taller people are generally healthier and have a lower risk of heart disease -- the leading killer in the U.S., ahead of cancer.

ABC News' Mikaela Conley and Mercy Edionwe contributed to this report.