Researchers suggest that the taller a person is, the greater their likelihood of developing cancer.
The team, from the Karolinska Institutet and University of Stockholm, both in Sweden, followed 5.5 million Swedish men and women between the years 1958 and 2011, or from the age of 20 up until 2011.
Dr. Emelie Benyi, a PhD student at Karolinska Institutet who led the study, believes this is the first time the association between height and cancer has been studied in men and women on such a large scale, although a link between height and cancer development has been found in other studies.
All the participants were born between 1938 and 1991 and their adult heights ranged from 100-225 cm.
The information about adult heights was collected from the Swedish Medical Birth, the Swedish Conscription, and the Swedish Passport Registers. The cancer data was retrieved from the Swedish Cancer Register.
The team found that for every additional 10 cm of height, the risk of developing cancer increased by 18% in women and 11% in men.
Previous studies have shown the same association between height and cancer. That is to say, taller individuals have a higher risk of developing different types of cancer, including breast cancer and melanoma.
Hormonal, environmental factors could be to blame
In the past, researchers have suggested that a basic common mechanism, possibly acting in early life, might be involved.
One possibility is that environmental factors that affect variations in height, including diet and infections during childhood, may play a role.
Another is that hormone levels, especially those related to growth, such as insulin-like growth factors (IGFs), might be relevant. Levels of IGFs are believed to affect cancer risk.
A further possibility is that taller people have more cells, including stem cells, exposing them to a greater opportunity for mutations leading to malignant transformation.
This would suggest that height is related to cancer risk through increased cell turnover, mediated by growth factors, or through increased cell numbers.
Dr. Benyi points out:
"It should be emphasized that our results reflect cancer incidence on a population level. As the cause of cancer is multifactorial, it is difficult to predict what impact our results have on cancer risk at the individual level."
The team hopes to further investigate how mortality from cancer and other causes of death are associated with height within the Swedish population. The question remains whether taller people are more likely to die specifically of cancer, or more likely to have an increased mortality rate overall.
Last year, Medical News Today reported on a study claiming to have uncovered why men and women differ in height.