Why does cancer kill
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Why Does Cancer Kill?
Cancer is a leading cause of death worldwide, responsible for nearly 10 million deaths annually. Understanding why cancer kills involves exploring the complex mechanisms of tumor growth, metastasis, and resistance to treatment.
Tumor Growth and Metastasis
Uncontrolled Cell Division and Tumor Formation
Cancer begins with the loss of normal control over cell division and differentiation, leading to the formation of a primary malignant tumor. These cancer cells can multiply uncontrollably, forming masses that disrupt the function of vital organs.
Metastasis: Spread of Cancer Cells
One of the most deadly aspects of cancer is metastasis, where cancer cells spread from the primary tumor to other parts of the body. This process can lead to the formation of secondary tumors in critical organs, severely impairing their function and leading to organ failure.
Resistance to Treatment
Mechanisms of Resistance
Cancer cells often develop resistance to treatments such as chemotherapy and radiotherapy. This resistance can occur through various mechanisms, including alterations in drug transport, metabolism, and the regulation of cell death pathways. Tumor cells may also evade immune-mediated killing by decreasing antigen expression or impairing the activation of T lymphocytes, leading to immune escape .
Genetic and Cellular Adaptations
Cancer cells can adapt genetically and metabolically to survive in hostile environments, including those created by therapeutic interventions. For instance, some cancer cells can enter a state of senescence, where they stop dividing but remain metabolically active, thereby evading cell death. Additionally, cancer cells can exploit cell competition to kill neighboring healthy cells, facilitating tumor expansion.
Immune Evasion
Evasion of Cytotoxic T Lymphocytes (CTLs)
Cancer cells can evade destruction by the immune system, particularly by cytotoxic T lymphocytes (CTLs). Genetic circuits within cancer cells enable them to resist CTL-mediated killing through various pathways, including the interferon response and autophagy. This evasion allows cancer cells to survive and proliferate despite the immune system's efforts to eliminate them.
Role of Immune Cells
While immune cells can destroy cancer cells, they often fail to completely eradicate tumors. Instead, they may induce a state of stable disease, where cancer growth is arrested but not entirely eliminated. This suggests that immune therapy may control cancer through mechanisms other than direct killing, such as inducing senescence in cancer cells.
Conclusion
Cancer kills through a combination of uncontrolled cell growth, metastasis, resistance to treatment, and evasion of the immune system. Understanding these mechanisms is crucial for developing more effective therapies and improving patient outcomes. By targeting the genetic and cellular adaptations that enable cancer survival, researchers hope to find new ways to combat this deadly disease.
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