Abstract C027: Racial variation in umbilical cord blood vitamin D concentrations and telomere length: Implications for cancer risk

Abstract

Abstract Background: Non-Hispanic Blacks (NHBs) experience a markedly higher cancer burden and cancer mortality compared to non-Hispanic Whites (NHWs). Several factors account for this disparity, including suboptimal or deficient vitamin D status. Vitamin D has an important role in cancer risk, disease/cancer progression and telomere biology. Given the documented cancer disparities between these groups, it is important to examine vitamin D concentrations and leukocyte telomere length in utero, a window of susceptibility for disease and cancer risk later in life. We investigated racial differences in neonate umbilical cord blood vitamin D concentrations, and whether differences in vitamin D concentrations are associated with umbilical cord blood telomere length by race and gender. Methods: In 2006-2007, pregnant women were recruited for the Expanded Hormones in Umbilical Cord Blood Study (EHUB) and followed to postpartum. Venous umbilical cord blood samples, along with maternal and birth characteristics, were collected in 39 NHB and 65 NHW full-term neonates. 25(OH)D and 1,25(OH)2D levels were assayed using an equilibrium radioimmunoassay procedure, and relative telomere length was measured by qPCR in leukocyte DNA. Geometric mean plasma concentrations of 25(OH)D and 1,25(OH)2D were calculated. Linear regression analysis was used to examine associations between neonatal cord blood 25(OH)D and 1,25(OH)2D concentrations and leukocyte telomere length by race and gender. Results: Compared to NHW mothers, NHBs were younger, had higher parity, were more likely to be overweight and obese prepregnancy, and more likely to be exposed to secondhand smoke. NHB neonates had lower birth lengths (19.4 versus 20.2 inches; p<.0001) and lower birth weights (3287 vs. 3425 gm) than NHW neonates. Compared to NHW neonates, NHBs had lower adjusted mean 25(OH)D (6.4, 95% CI: 5.4-7.6 ng/mL versus 16.4, 95% CI: 14.2-18.9 pg./mL; p<.0001) and lower 1,25(OH)2D concentrations (51.1, 95% CI: 43.3-60.4 pg./mL versus 71.7, 95% CI: 62.6-82.0 pg./mL; p<.0003). After adjusting for race and gender, 25(OH)D and 1, 25(OH)2D concentrations were not associated with telomere length. There was an interaction between race and vitamin D, but not gender and vitamin D on telomere length. Compared to NHWs, NHB neonates had shorter telomere lengths per increase in vitamin D concentrations (-0.83 per unit of 25(OH)D and -0.79 per unit of 1,25(OH)2D). The interaction persisted after adjusting for maternal and birth characteristics. Conclusion: We did not find an association between umbilical cord blood vitamin D concentrations and telomere length. Instead, our findings suggest an interaction between race and umbilical cord blood vitamin D on telomere length. Further research is warranted to understand whether the effect of in utero exposure to vitamin D concentration on telomere length can inform the underlying mechanisms that are associated with cancer disparities in adulthood. Citation Format: Tanya Agurs-Collins, John Barber, Jessica Bienstock, Paige Green, Christopher Heaphy, Jiayun Lu, Alan Meeker, Anthony Rizzo, Sabine Rohrmann, Elizabeth Platz. Racial variation in umbilical cord blood vitamin D concentrations and telomere length: Implications for cancer risk [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C027.