Abstract 832: Midlife racial differences In leukocyte telomere length and in associations between modifiable factors and telomere length
Authors: Weber Kari A. , Heaphy Christopher M. , Giovannucci Edward , Platz Elizabeth A. , Meeker Alan K. ,   Health Professionals Follow-up Study Investigators
Published: August 2015

Abstract
Background: We previously investigated whether cord blood leukocyte telomere length differs by race as a way to assess the role of early life factors in the prostate cancer racial disparity. We hypothesized that telomere length is shorter in black neonates given their 60% higher adult prostate cancer risk, but did not observe a racial difference. Whether peripheral blood leukocyte telomere length differs by race in midlife - after decades of exposures that shorten telomeres - has not been addressed in detail. Obesity, inactivity, and smoking have been associated with shorter leukocyte telomere length. These factors are among the few purported risk factors for lethal prostate cancer that are modifiable and for which prevalence differs by race. Thus, we examined whether telomere length is shorter in black men, evaluated associations between modifiable factors and telomere length overall and by race, and assessed whether associations between modifiable factors and telomere length influenced any racial difference in telomere length. Methods: The Health Professionals Follow-up Study is a cohort of US men aged 40-75 years followed since 1986. At baseline and biennially men completed questionnaires on lifestyle and medical factors. Blood was collected in 1993-95. We measured telomere length (telomere/single copy gene) by quantitative PCR for a subset: 43 black and 56 white men without cancer. We estimated associations between modifiable factors and the natural logarithm of telomere length overall and by race using linear regression to adjust for age, and evaluated interactions using the likelihood ratio test. We estimated geometric mean telomere length and 95% confidence intervals (CI) for black and white men using linear regression to adjust for age and further for modifiable factors. Results: Black and white men did not differ in age or waist circumference, but black men were less physically active (total) and more likely to smoke. Waist (per 1” increase: β = -0.03; p = 0.002), inactivity (per 1 MET-hr/wk decrease: β = -0.003; p = 0.09), and smoking (current vs not: β = -0.25; p = 0.06) were inversely associated with ln telomere length. The association for waist was stronger in black (β = -0.04; p = 0.005) than white (β = -0.01; p = 0.3) men (p-interaction = 0.1). Associations for inactivity (p-interaction = 0.1) and smoking did not differ by race (p-interaction = 0.4). Geometric mean telomere length did not differ by race adjusting for age (black: 1.42, 95% CI 1.28-1.58; white: 1.38, 95% CI 1.26-1.50), or further adjusting for waist, inactivity, and smoking (black: 1.43, 95% CI 1.28-1.59; white: 1.35, 95% CI 1.23-1.48). Conclusion: Telomere length did not differ between black and white men. Lethal prostate cancer risk factors - waist, inactivity, and smoking, were associated with shorter telomere length in all men, and waist more strongly so in black men.
Citation Format: Kari A. Weber, Christopher M. Heaphy, Edward Giovannucci, Elizabeth A. Platz, Alan K. Meeker, Health Professionals Follow-up Study Investigators. Midlife racial differences In leukocyte telomere length and in associations between modifiable factors and telomere length. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 832. doi:10.1158/1538-7445.AM2015-832