Height Differences May Explain Excess Cancer Risk for Men
Most cancers occur more frequently in men than in women and greater height has been associated with increased risk for some cancers. In a study reported in Journal of the National Cancer Institute, Roland B. Walter, MD, PhD, of the Fred Hutchinson Cancer Research Center, and colleagues found that 33.8% of the excess risk of cancer in men was accounted for by height differences between men and women. Height-associated risk was greatest for kidney cancers, melanoma, and hematologic malignancies.
Study Details
The study involved 3,466 cancers of shared anatomic sites prospectively identified through the Surveillance, Epidemiology, and End Results cancer registry from among more than 65,000 subjects aged 50 to 76 years recruited to the Vitamins And Lifestyle (VITAL) study. Age- and race-adjusted hazard ratios (HRs) for the associations between sex and incident cancers were estimated with and without adjustment for height and height squared. Among all subjects in the VITAL study, men were more educated and heavier than women, exercised more, consumed more alcohol, smoked more in their lifetime, and consumed more red meat and fewer vegetables. Men had significantly greater height (mean = 70.7 vs 64.7 inches).
Greater Risk for Men
Overall, men had a 55% increased risk of cancer at shared sites (HR = 1.55, 95% confidence interval [CI] = 1.45–1.66), including greater risk for gastrointestinal tract, lung, urinary system, melanoma, and hematologic malignancies, and most specific cancer types within these organ systems.
After adjustment for more than 35 lifestyle and medical risk factors, the hazard ratios for risk among men were attenuated, but overall shared-site cancer risk remained significantly higher among men (HR = 1.39, 95% CI = 1.21–1.60), with men having increased risk for urinary system cancers, melanoma, and hematologic cancers. After adjustment, sex was no longer associated with risk for lung and total gastrointestinal cancers.
Effect of Height
When height was adjusted for risk modeling, the sex-related differences in risk were reduced, indicating the contribution of height to risk. On modeling accounting for height, 33.8% (95% CI = 10.2%–57.3%) of the excess risk for men was explained by the height difference between sexes (for height squared, HR = 1.34, 95% CI = 1.21–1.48). The proportion of risk mediated by height was 90.9%, 57.3%, and 49.6% for kidney cancer, melanoma, and hematologic malignancies, respectively, with there being little evidence that height mediated the sex differences in risk for gastrointestinal tract, lung, and bladder cancers. By comparison, modeling including the multiple other lifestyle and medical risk factors showed that these factors accounted for a nonsignificant 23.1% of the sex difference in cancer risk at shared sites.
The investigators noted that one proposed mechanism for height-associated risk is that “taller individuals may be at increased risk of cancer because of a larger number of cells and higher rate of cell divisions within tissues.” They concluded, “Height is an important explanatory factor for the excess risk for men for many shared-site cancers. This suggests that some of the excess risk is due to factors associated with height (eg, number of susceptible cells in a specific organ or growth-influencing exposures in childhood).”
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
