cancer
Summary
Cancer is a group of diseases characterized by uncontrolled cellular growth and proliferation due to genetic mutations that disrupt normal cell cycle regulation. Malignant cells can invade surrounding tissues and metastasize to distant sites through lymphatic and hematogenous spread. Cancer is the second leading cause of death globally and requires understanding of oncogenes, tumor suppressor genes, and the hallmarks of cancer.
Detail
Cancer arises from accumulation of genetic mutations that affect key regulatory pathways controlling cell division, apoptosis, and DNA repair. The hallmarks of cancer include sustained proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion/metastasis. Oncogenes (e.g., RAS, MYC) promote cell growth when activated, while tumor suppressor genes (e.g., p53, RB) normally prevent uncontrolled proliferation. Loss of p53 function is found in >50% of cancers, eliminating a critical DNA damage checkpoint. Cancer cells exhibit genomic instability, altered metabolism (Warburg effect), and immune evasion. Metastasis occurs through epithelial-mesenchymal transition, allowing cells to enter circulation and establish secondary tumors. Risk factors include age, genetic predisposition, environmental carcinogens, infections (HPV, HBV, H. pylori), and lifestyle factors. Diagnosis involves histopathology, staging (TNM system), and molecular markers. Treatment includes surgery, chemotherapy, radiation, immunotherapy, and targeted therapy based on specific mutations.
Sources
- Robbins and Cotran Pathologic Basis of Disease
- First Aid for the USMLE Step 1
- Weinberg - The Biology of Cancer
- DeVita's Cancer: Principles and Practice of Oncology
- Pathoma - Fundamentals of Pathology
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