The tumor microenvironment refers to the complex network of cells, molecules, and structures that surround and interact with cancer cells within a tumor. This environment plays a crucial role in regulating tumor growth, progression, and response to therapy. It includes various immune cells, stromal cells, blood vessels, extracellular matrix components, and signaling molecules that can either promote or inhibit tumor growth and metastasis. Understanding and targeting the tumor microenvironment is a key focus of cancer research, as it has the potential to improve the effectiveness of cancer treatments and develop new therapeutic strategies.