Your risk of getting cancer goes up significantly if you are tall and that holds with both men and women, say researchers who carried out a long-term study in Sweden.

For every extra 4 inches in height, the risk of developing some form of cancer goes up 11 percent for men and 18 percent for women, say scientists with the Karolinska Institutet and the University of Stockholm.

The risk is even greater for certain types of cancer, they found; taller women have a 20 percent greater risk of developing breast cancer, while there is a 30 percent greater chance of developing melanoma in both women and men with every 4 inches of greater height.

For the study, the researchers looked at data on 5.5 million Swedish adult men and women born between 1938 and 1991, with heights ranging up to 7 feet, 4 inches.

"To our knowledge, this is the largest study performed on linkage between height and cancer including both women and men," says lead researcher Emelie Benyi of the Karolinska Institutet, a medical university.

The scientists emphasize that their study can only reflect cancer on a population-wide level, not for individuals.

"As the cause of cancer is multifactorial, it is difficult to predict what impact our results have on cancer risk at the individual level," Benyi says.

While a link between height and cancer may seem strange, the number of cells in a person's body might be related to the level of cancer risk, say other experts.

"A cancer arises by mutations from a single normal cell," explains University of London scientist Dorothy Bennett.

A person's height could determine the number of cells "at risk," she says. "Bigger people have more cells."

Some other researchers have questioned the study's findings, suggesting other factors such as genetics or obesity have been shown to be stronger links to a person's cancer risk.

The Swedish researchers acknowledge that height alone may not be increasing cancer risks, but rather that growth hormones may be a factor in both pushing people toward being taller and having greater cancer risks.

The researchers say further study is needed to find out how mortality from cancer compares with other causes of death when it comes to a person's height.

"Our studies show that taller individuals are more likely to develop cancer but it is unclear so far if they also have a higher risk of dying from cancer or have an increased mortality overall," Benyi says.

Photo: Amelia Reising | Flickr