Cancer Biology

Cancer is not simply uncontrolled cell growth. It is an evolving biological system in which genetic and epigenetic alterations reshape cellular behavior, disrupt tissue organization, alter interactions with the tumor microenvironment, and create populations capable of invasion, metastasis, persistence, and resistance to treatment.Cancer Biology presents cancer through this mechanistic framework, connecting molecular alterations to cellular behavior, tumor evolution, clinical phenotype, and therapeutic response.The book begins with the biological systems that normally regulate cellular growth, survival, differentiation, genomic integrity, and tissue organization. It then examines how these controls become disrupted through cancer genetics, oncogenes, tumor suppressor genes, DNA damage and repair defects, genomic instability, and epigenetic reprogramming.Particular attention is given to the evolutionary nature of cancer. Tumors are composed of genetically and phenotypically diverse populations that compete, adapt, and respond differently to changing conditions. Clonal evolution, tumor heterogeneity, cellular plasticity, cancer metabolism, replicative immortality, and treatment-driven selection are therefore considered as interconnected processes rather than isolated concepts.The biology of the tumor extends beyond the malignant cell. The tumor microenvironment, including cancer-associated fibroblasts, extracellular matrix, blood vessels, immune cells, inflammatory signals, oxygen availability, and metabolic conditions, can influence tumor growth, invasion, metastasis, immune evasion, and therapeutic response.The book also connects fundamental cancer biology with clinical practice, covering:Cancer genetics, genomics, mutations, copy-number alterations, gene fusions, and driver alterationsOncogenes and tumor suppressors, including TP53, RB, RAS-RAF-MEK-ERK, PI3K-AKT-mTOR, and WNT/β-cateninDNA damage, DNA repair, replication stress, and genomic instabilityEpigenetic regulation, chromatin remodeling, cellular identity, and plasticityClonal evolution, tumor heterogeneity, cancer-cell states, and tumor persistenceCancer metabolism, hypoxia, angiogenesis, inflammation, and the tumor microenvironmentImmune surveillance, immune evasion, immunoediting, and tumor immunologyInvasion, metastasis, organ colonization, dormancy, residual disease, and recurrencePathology, molecular classification, biomarkers, liquid biopsy, staging, and early detectionCancer treatment, including surgery, radiation, cytotoxic, targeted, endocrine, and immune-based therapiesPrecision oncology, single-cell and spatial biology, functional genomics, artificial intelligence, and patient-derived modelsThe emphasis throughout is not merely on what changes in cancer, but on what those changes allow the cancer cell or tumor to do.