Million Women Study: taller people have greater cancer risks?

A study of over one million middle-aged women and 17 cancer types reveal that the risk rises 16% for every 4 inches in height.
Written by Janet Fang, Contributor

Across all socioeconomic levels, tall women are more likely to develop cancer, a new study reveals.

The risk of cancer rose 16% with every additional 10 centimeters (or 4 inches) above 5 feet in height. But scientists don't know why.

"Obviously height itself cannot affect cancer,” says lead researcher Jane Green from the University of Oxford, “but it may be a marker for something else."

It’s possible that the very hormones that allow children to grow tall also stimulate the growth of their cancer cells.

In the largest study of height and cancer risk to date, Green and colleagues looked at the incidence of 17 cancer types, over 9 years, among 1,297,124 middle-aged women in a UK health study called the Million Women Study. During that time, 97,376 cancers were found.

  • Even after taking into account factors such as socioeconomic status, alcohol use, and body-mass index, the researchers found that cancer risk significantly increased with height for 10 out of the 17 cancers studied.
  • The increased risk was greatest for skin cancer (32%), kidney cancer (29%), and leukemia (26%).
  • The risk of breast cancer, the most common cancer in the study, increased 17% with every 4 inches.
  • Those in the tallest group (over 5 feet 9 inches) were 37% more likely to have developed a tumor than those in the shortest group (under 5 feet).

From a basic questionnaire, generally speaking, taller women tended to drink more alcohol and had fewer children than shorter women, HealthDay summarizes. Taller women were also less obese, less likely to smoke, wealthier, and more active.

However, among women who smoked, smoking played a more pivotal role than height.

The link between height and cancer risk was similar when these data were pooled with 10 previous studies of cancer and height in Europe, Asia, Australia, and North America.

“The fact that the link between height and cancer risk seems to be common to many different types of cancer in different people suggests there may be a basic common mechanism, perhaps acting early in peoples' lives, when they are growing,” Green says.

They think, but have not proved, that growth hormones may be the explanation. Higher levels of growth factors could do two things, BBC explains:

  1. They could result in more cells – taller people are made of more stuff so there are more cells that could mutate and become tumors.
  2. Alternatively, they could increase the rate of cell division and turnover, increasing the risk of cancer.

The adult height of European populations has risen 1 centimeter per decade since 1900, and the researchers say this could have increased cancer incidence 10% to 15%.

But taller women shouldn’t worry or look to treatments to stunt growth, Green adds.

The study was published in The Lancet Oncology yesterday.

Image by biberta via morgueFile

This post was originally published on Smartplanet.com

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