New research has shown that taller women could be more prone to suffering from cancer. The British study published online in the medical journal The Lancet on Thursday said cancer risk rose about 16% for every 4-inch rise in height. Increasing height heightened the chances of cancers of breast, ovary, womb, bowel, leukemia and malignant melanoma (skin cancer) the study found.
Lead author Jane Green from the University of Oxford and her colleagues looked at 1.3 million middle-aged women in the UK enrolled between 1996 and 2001. During an average follow-up time of about 10 years, 97,000 cases of cancer were identified. The tallest women were about 5 feet 10 inches or taller and the shortest ones in the study measured about 5 feet 1 inch or less. The average height was between 5 feet 3 inches and 5 feet 4 inches.
Results showed that the relative risk (RR) for total cancer was 1.16 times for every 10 cm rise in height. This rise in risk was seen irrespective of their date of birth, socio-economic status, body mass index, alcohol intake, physical activity, age when they began menstruating, use of oral contraceptive and hormone replacement therapy — factors that are known to affect cancer risk. The risk increased for 15 of the 17 cancer sites assessed, and was statistically significant for 10 of these (more than earlier thought): malignant melanoma (1.32), kidney (1.29), leukemia (1·26), colon (1.25), non-Hodgkin lymphoma (1·21), CNS (1.20), endometrium (1.19), breast (1.17), ovary (1.17) and rectum (1.14).
Green said, “We showed that the link between greater height and increased total cancer risk is similar across many different populations from Asia, Australasia, Europe and North America. The link between height and cancer risk seems to be common to many different types of cancer and in different people suggesting that there may be a basic common mechanism, perhaps acting early in peoples' lives, when they are growing.”
The reason behind the link is unclear. One possibility, according to them, is that taller women may have higher levels of growth-related hormones — both in childhood and adulthood — and these growth-related hormones may modestly increase cancer risk. The authors write, “Adult height reaches its maximum between the ages of 20 and 30 years. Variation in height relates to genetic and environmental influences acting mostly in the first 20 years, or so, of life; environmental factors, including childhood nutrition and infections, are believed to predominate. Hormone levels, especially of growth factors such as insulin-like growth factors (IGFs), might be relevant. Circulating levels of IGFs in adulthood and childhood affect cancer risk…Another possibility is that height predicts cancer risk because taller people have more cells (including stem cells), and thus a greater opportunity for mutations leading to malignant transformation. Height might thus be related to cancer risk through increased cell turnover mediated by growth factors, or through increased cell numbers.”
This wasn’t the first study focusing on height. Dr. Jaime Guevara-Aguirre of Quito, Ecuador found that people of “severely short stature” are less likely to develop cancer or diabetes during a twenty-two-year study of 99 Ecuadorian dwarfs. Throughout this study, only one woman got cancer. After treatment, it was later reported that she was cancer-free.
Other studies show higher risks for men also. Dr. Michael Blaise Cook suggests that several factors linked to height may be associated with risk of testicular cancer. After the analysis of thirteen previous studies, U.S. researchers found that every extra two inches in height raises the risk of testicular cancer by13 percent.
More research will be necessary to further confirm these studies. In the meantime, everyone should be much more concerned with lifestyle factors, including smoking, sun exposure and unsafe sex, which increase the risk of developing cancer suggest researchers.