Explaining racial disparity in aggressive prostate cancer: How Vitamin D might be the key
Studies have reported that African American men in the United States face an increased risk of developing a more aggressive form of prostate cancer and an increased mortality rate from the disease compared to white men . The source of this racial disparity has been a hot topic for debate in recent years.
Much of the research has pointed to a racial gap in socioeconomic status, which relates to important factors such as access to health care services and insurance, as a key driver of the stark differences in early cancer diagnoses and survival rates between white and African American men . As such, initiatives such as ‘Close the Gap’ have been developed in order to help educate and eliminate inequalities in cancer outcomes. Nevertheless, as important as the environmental drivers are, research has recently been published that suggests there may be more to the story.
Scientists at Ohio State University and Tuskegee University have been looking into the possibility of a biological basis for the racial disparity in prostate cancer. This proposal does not deny the effects of drivers like socioeconomic status, rather indicates that there may be a combination of causes. Specifically, the study suggested that Vitamin D may have a different role in the bodies of African American men compared to white men . This different role might be an explanation for the higher risk for Vitamin D deficiency in African Americans than their white counterparts , which has been known for many years, and which could play a role in cancer risk.
How exactly is Vitamin D processed differently in the bodies of African American men? It has to do with Vitamin D receptors, which are proteins that help the body use the Vitamin D that it gets from food and sunlight. These receptors attach to sections of DNA to regulate gene activity and thereby control various bodily processes. What the study in question found was that Vitamin D receptors attach to different and fewer sections of DNA in healthy white men than in healthy African American men. An important difference was that Vitamin D receptors seemed to regulate genes associated with inflammation in African American men, which is believed to have a role in many cancers. Following a similar pattern, the study also found that even though prostate cancer weakens Vitamin D receptors’ ability to bind to cells, they still regulate some 600 genes in African American men’s prostate cancer compared to none in white men’s prostate tumors . Therefore, it is clear that there may be important biological differences in the role of Vitamin D across racial groups, and more study on this interesting topic is certainly warranted.
The link between Vitamin D and prostate cancer has a complicated history. Various clinical and longitudinal trials over the years have been underpowered or have not carefully represented different racial groups. At NBRI, we are currently conducting a systematic review on the link between Vitamin D supplementation and cancer risk and mortality to help clarify one aspect of the complex relationship.
 DeSantis CE, Siegel RL, Sauer AG, et al. Cancer statistics for African Americans, 2016: progress and opportunities in reducing racial disparities. CA Cancer J Clin. 2016;66(4):290-308. doi:10.3322/caac.21340
 Dess RT, Hartman HE, Mahal BA, et al. Association of Black Race With Prostate Cancer–Specific and Other-Cause Mortality. JAMA Oncol. 2019;5(7):975–983. doi:10.1001/jamaoncol.2019.0826
 Siddappa, M., White, J., Wang, H., Sucheston-Campbell, L. E., Yates, C., & Campbell, M. J. (2018). Abstract B016: MicroRNA drivers of TMPRSS2 fusion-negative prostate cancer in African Americans.
 Susan S. Harris, Vitamin D and African Americans, The Journal of Nutrition, Volume 136, Issue 4, April 2006, Pages 1126–1129, https://doi.org/10.1093/jn/136.4.1126