BACKGROUND:Cardiovascular disease (CVD) is a leading cause of death in men with prostate cancer. In addition, non-Hispanic Black (NHB) men experience worse CVD-related mortality compared to their non-Hispanic White (NHW) counterparts, although the reason for this racial disparity remains unclear. Notably, vascular endothelial dysfunction often precedes the emergence of overt CVD. Indeed, conduit-vessel dysfunction, micro-vascular dysfunction, and arterial stiffness are independent predictors of CVD risk. Thus, the purpose of this study was to comprehensively assess vascular health in recently diagnosed NHB and NHW men with prostate cancer. Methods: Twenty-eight men (10 NHW, 18 NHB) with a new clinical diagnosis of prostate cancer (within 3 months) participated in this study. Flow-mediated dilation (FMD) was performed to represent conduit-vessel vascular endothelial function. Cutaneous post occlusive reactive hyperemia (PORH) with local thermal heating (LTH) and iontophoresis of acetylcholine were performed to represent various mechanisms regulating microvascular function. Lastly, pulse wave velocity (PWV) and pulse wave analysis (PWA) were performed to assess central and aortic stiffness, respectively. Data are reported as mean ± SD. Results: A 4-year age difference ( p=0.131) was observed between NHB (65±7 years) and NHW (69±6 years) men. No differences in BMI or clinical laboratory values were observed between NHB and NHW patients (all p>0.05). NHB men exhibited significantly lower microvascular function compared to NHW men, including PORH (NHB: 117±44 PU vs NHW: 207±47 PU; p<0.001), LTH (NHB: 180±73 PU vs NHW: 281±65 PU; p=0.003), and iontophoresis (NHB: 67±28 PU vs NHW: 136±38 PU; p<0.001). No differences in FMD ( p=0.596), PWV ( p=0.695), or PWA ( p=0.883) were observed between groups. CONCLUSION: The results of the current study provide compelling evidence that microvascular dysfunction is present in NHB men who are recently diagnosed with prostate cancer compared to their NHW counterparts. Given that NHB men were 4 years younger, these data support that the microvascular dysfunction may accelerate vascular aging and contribute to the racial disparity in CVD following prostate cancer diagnosis. Supported by: AHA SFRN 863621 (RAH). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.