Prognostic role found for miR-21 expression in triple-negative breast cancer

(Elsevier Health Sciences) 'Triple-negative' breast cancer occurs in patients whose cells do not express receptors for estrogen, progesterone, and/or human epidermal growth factor receptor 2 (ER/PR/HER2). Because of the absence of these predictive biomarkers, treatment assignment can be difficult. Now, researchers report that high levels of the microRNA miR-21 in the tumor microenvironment, but not in the tumor epithelia, are associated with worse clinical outcomes for patients with triple-negat...