Khan S, et al. - Given metformin has been associated with a reduced incidence of prostate cancer and improved prostate cancer outcomes, researchers investigated the possible influence of race on the link between metformin use and prostate cancer aggressiveness. For this purpose, they performed separate assessments for this link among 305 Black Americans (Blacks) and 195 White Americans (Whites) who were research participants with incident prostate cancer and self-reported diabetes from the North Carolina–Louisiana Prostate Cancer Project. Findings demonstrated a positive association of metformin use with high-aggressive prostate cancer in Blacks. By contrast, Whites demonstrated a weak inverse link between metformin use and high-aggressive prostate cancer. Race could modify the link between metformin use and prostate cancer aggressiveness.