tumormilieus

Tumor microenvironment, or tumormilieus in German-language texts, refers to the ecosystem of non-tumor cells, extracellular matrix, and signaling milieu surrounding and interacting with tumor cells. It encompasses various cell types, including stromal and immune cells, blood vessels and supporting tissue, as well as soluble factors such as cytokines, chemokines, and growth factors. The microenvironment is dynamic and evolves during tumor development.

Key components include cancer-associated fibroblasts, mesenchymal stem cells, endothelial cells, pericytes, adipocytes, and a heterogeneous immune cell infiltrate that can contain T cells, B cells, macrophages, dendritic cells, neutrophils, and myeloid-derived suppressor cells. The extracellular matrix provides structural support and biochemical cues, while physical aspects such as hypoxia, low pH, and high interstitial pressure shape cellular behavior. Interactions occur via cell–cell contact and secreted factors, creating a network of signaling loops between tumor and stromal cells.

The tumormilieus influences tumor growth, angiogenesis, invasion, metastasis and response to therapy. In many cancers, stromal and immune components promote immune suppression and therapeutic resistance, while in other contexts they may restrain growth. Spatial organization and temporal dynamics of the microenvironment contribute to heterogeneity within and between tumors.

Studying tumormilieus involves biopsy analysis, single-cell sequencing, spatial transcriptomics, imaging, and model systems such as organoids and patient-derived xenografts. Therapeutic approaches target components of the microenvironment, including anti-angiogenic strategies, stromal modulation, and immunotherapies that reprogram immune cells. Clinical outcomes depend on tumor type and stage, and interventions aimed at the microenvironment can yield complex, context-dependent effects. In German-language literature, tumormilieus corresponds to the tumor microenvironment.