July 20, 2011 -- Taller women are at greater risk for many types of cancers compared with shorter women, a new study suggests.
In the study, cancer risk rose by about 16% for every 4-inch increase in height. The risk of total cancer increased with height, as did the risk of many different types of cancer including breast, ovary, uterine, and colon cancer as well as leukemia and melanoma, a potentially fatal form of skin cancer.
The findings appear online in the Lancet Oncology.
Several studies have linked height to cancer risk, but the precise nature of the relationship is still poorly understood. "Growth hormones are one theory [as] they have been linked to both height and cancer risk in childhood or in adult life, or tall people may simply have a greater chance of cancerous cell changes, because they have more cells," says study researcher Jane Green of the Cancer Epidemiology Unit at the University of Oxford, U.K., in an email.
Green and colleagues looked at the relationship between height and cancer among 1.3 million middle-aged women who were enrolled between 1996 and 2001. During an average follow-up of 10 years, there were 97,376 cases of cancer.
Women were grouped into six categories based on their height when they were recruited into the study. The tallest women were about 5 feet 10 inches or taller and the shortest women in the study measured about 5 feet 1 inch or less. There were about 8 and 1/4 inches between the tallest and shortest women in the study; the average height was between 5 feet 3 inches and 5 feet 4 inches.
Taller women were at higher risk for all cancers, and this increased risk was seen regardless of the year they were born, socioeconomic status, body mass index, alcohol intake, physical activity, age when they began menstruating, use of oral contraceptive and hormone replacement therapy, and other factors that are known to affect cancer risk.
The increased risk associated with height was lower for smoking-related cancers among current smokers, the study showed.
The researchers also combined their results with those from 10 previous studies to show that the findings also hold across Europe, North America, Australia, and Asia.
Explaining the Height-Cancer Link
"The importance of this research is in understanding how cancers develop," Green says. "Because height is linked to a wide range of cancers in a wide range of people, it may give us a clue to a basic common mechanism for cancer."
Going forward, "it will be interesting to look in more detail at possible mechanisms, and at the relationship between cancer risk and more detailed aspects of height and growth in childhood," she says.
"Taller people in general are healthier and have lower risk of heart disease, and most people are not very much taller or shorter than average, so their cancer risk is not much different from the average risks usually quoted," she says.