Study: Cancer Risk Higher for Taller Women After Menopause

A study published today in Cancer, Epidemiology Biomarkers, and Prevention, a journal of the American Association for Cancer Research has linked higher stature in women after menopause with a higher risk of developing any of 19 cancer types.

The study, led by Geoffrey Kabat, PhD, an epidemiologist at the Albert Einstein College of Medicine of Yeshiva University in New York, and colleagues from the Baylor College of Medicine in Houston and other medical schools, analyzed more than 144,000 women who participated in the Women’s Health Initiative. After following the women for a median of 12 years, 20,928 women had an invasive cancer diagnosis.

Previous prospective studies of Asian and Western populations have suggested that height may be an independent risk factor for cancer although how much the risk is increased is inconsistent among the studies.

In the current study, for every 10-cm increase in height, the relative risk of developing any cancer went up by 13%. Higher stature was linked to a spectrum of different cancers: breast, colon, endometrial, kidney, melanoma, multiple myeloma, ovary, rectum, and thyroid. The link was not changed after adjusting for known variables that influence the risk of these cancers (weight, age, hormone therapy, smoking, alcohol consumption, age at menarche, education, ethnicity, and weight/height ratio). For example, for each 10-cm increase in height, the relative risk of breast cancer increased by 13%, and by 29% for multiple myeloma and thyroid cancer. The increased risk of melanoma and colon, ovarian, and endometrial cancers ranged from 13% to 17%. No specific cancer showed a negative association with height.

The current analysis excluded women with a prior history of cancer, except those with nonmelanoma skin cancer. Women in the study were between the age of 50 and 79 at the onset of the Women’s Health Initiative study.

After comparing the results of other large cohort studies analyzing the link of height with different cancer types, the authors conclude that “the associations of height with risk of melanoma and with cancers of the thyroid, ovary, colorectum, breast, endometrium, and kidney are unlikely to be due to confounding.”

The link between height with colon, cervical, brain, lung cancer, and Non-Hodgkin lymphoma was only bordering on significant.

The association of height with any cancer did not differ as a result of smoking history, however there were few current smokers included among the participants.

The association also did not change when history of cancer screening-such as mammograms, Pap smear, and colorectal cancer testing-was factored in.

“We were surprised at the number of cancer sites that were positively associated with height. In this data set, more cancers are associated with height than were associated with body mass index,” said Kabat, in a statement. “Ultimately, cancer is a result of processes having to do with growth, so it makes sense that hormones or other growth factors that influence height may also influence cancer risk.”

The link of height with cancer risk still needs to be validated with further studies. The mechanism of how stature influences cancer risk is unclear. The two major proposed mechanisms are either higher levels of growth factors in taller individuals or greater organ size and therefore greater number of cells in taller individuals which increases the probability that any one cell could become malignant.

According to the authors, height is partly a reflection of environmental exposures. Specifically, studies have shown that height is associated with higher consumption of milk and calories in childhood and adolescence, and with higher circulating levels of insulin-like growth factor. Height can also be linked to steroid hormones and other growth factors.

Many more studies are needed to understand the connection between height and cancer risk including the underlying factors, both genetic and environmental that may influence height and could predispose women to cancer. The current study did not tease out the two major height measurements: leg length and torso length. Understanding whether there is also a link in men and in premenopausal women is needed. Future studies will need to better understand how events and genetic factors during childhood growth can influence cancer risk in adulthood.