Tumorstroma

Tumorstroma refers to the non-neoplastic, supportive tissue surrounding tumor cells. It forms the tumor microenvironment together with the malignant cell population and interacts with cancer cells in a bidirectional manner. The stroma includes a diverse array of cells, extracellular matrix, and soluble factors that influence tumor biology and progression.

Major components of the tumorstroma include the extracellular matrix, including collagens, fibronectin, and laminin, as well as stromal cells such as cancer-associated fibroblasts (CAF), pericytes, and endothelial cells. Immune cells (such as macrophages, T lymphocytes, and neutrophils), adipocytes, and resident fibroblasts are also part of the stromal compartment. In addition, soluble mediators such as cytokines and growth factors (for example TGF-β, PDGF, VEGF) contribute to signaling within the stroma. CAFs, in particular, are a prominent driver of stromal remodeling and signaling.

Functions of the tumorstroma include providing structural support and regulating interstitial pressure, remodeling the extracellular matrix through proteases like matrix metalloproteinases, and producing growth factors that promote angiogenesis and tumor cell survival. The stroma modulates immune cell recruitment and activity and can influence tumor cell proliferation, invasion, and metastatic potential through both direct cell contact and ECM-dependent signaling. Desmoplastic reactions, characterized by dense fibrous stroma, are seen in several cancers and can alter tumor mechanics and perfusion.

Clinical relevance is underscored by the stromal impact on drug delivery and treatment response; a dense or immunosuppressive stroma can hinder therapy, while stromal-targeting strategies aim to normalize the ECM, modulate immune activity, or inhibit stromal support of tumor growth. Stromal composition and activity vary by tumor type and stage, reflecting contextual roles in cancer.