Cancer Biology and Tumor Microenvironment explores the fundamental processes that drive cancer initiation, progression, and treatment resistance. Cancer biology focuses on genetic mutations, abnormal cell signaling, and uncontrolled cell division caused by the activation of oncogenes and loss of tumor suppressor genes. These changes lead to the formation of malignant tumors capable of invading surrounding tissues and spreading to distant organs. The tumor microenvironment (TME) includes a complex network of non-cancerous cells such as immune cells, fibroblasts, endothelial cells, and components like cytokines and extracellular matrix. The TME plays a critical role in supporting tumor growth, angiogenesis, immune evasion, and metastasis. Understanding the dynamic interaction between cancer cells and the TME is crucial for developing targeted therapies, immunotherapies, and improving clinical outcomes in cancer treatment.