Cancers at most anatomic sites occur more frequently in men compared to women. Differences in occupation, lifestyles, and sex hormones have been proposed as reasons for this difference. Now researchers have come up with a simpler reason for some of the sex related differences. Body size and height appear to account for a significant portion of this difference.
This week, in an early online edition of Journal of the National Cancer Institute, researchers followed over 65,000 adults aged 50 to 75 years old enrolled in the Vitamins And Lifestyle Study (VITALS) between 2000 and 2009. Risk factors for various cancers and height plus height squared, a measure of body size, were evaluated.
Overall, men had a 55% higher risk of cancer at shared anatomic sites. 34% of the excess cancers were explained by differences in height between sexes. For melanoma, hematologic (blood), and kidney cancers, height accounted for 57%, 50%, and 91% of the excess risk of cancer in men compared to women.
The authors commented that men are taller than women on average. Excess height and size means that there are more cells that might develop into cancer, more cells are dividing at any one time, and more cells are exposed to hormones and other factors that influence growth in men compared women.