Cancers are heterogeneous multicellular enterprises whose growth is dependent upon reciprocal interactions between genetically altered ‘initiated’ cells and the dynamic microenvironments in which they live. This meeting on TUMOR MICROENVIRONMENT (TME) will embrace tumor cell-intrinsic and -extrinsic communication programs regulating neoplastic progression, systemic aspects of host response to cancer (aging, cachexia, obesity, tumor immunity) impacting disease progression and response to therapy, and feature presentations discussing innovative experimental and computational tools designed to identify tumor vulnerabilities amenable for therapeutic targeting or patient stratification. Also included will be a workshop/data jamboree leveraging analytical tools developed by the NCI Human Tumor Atlas Data (HTAN) to study the TME.