How does cancer start
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Understanding How Cancer Starts
Genetic Mutations and Cancer Initiation
Cancer begins with genetic mutations that alter the normal function of cells. These mutations can be in proto-oncogenes, which when mutated become oncogenes with gain-of-function properties, or in tumor suppressor genes, which lose their function due to mutations. The accumulation of these mutations leads to uncontrolled cell growth and the formation of tumors .
Clonal Selection and Evolution
Once initial mutations occur, a process called clonal selection takes place. This is an evolutionary process where cells with advantageous mutations proliferate more than others, leading to the growth of pre-cancerous and cancerous cells. This process is driven by mutations that enhance cell survival and proliferation, making the cancer cells more robust.
Role of DNA Repair Genes
DNA repair genes, which are a subset of tumor suppressor genes, play a crucial role in maintaining genomic integrity. When these genes are inactivated by mutations, the rate of mutations in other genes increases, accelerating the progression from a pre-cancerous state to full-blown cancer. This mutator phenotype is a key factor in the rapid development of cancer once the initial bottleneck of mutation accumulation is surpassed.
Dynamics of Cancer Initiation
The initiation of cancer is a dynamic process influenced by the type of mutations. Neutral mutations lead to slower cancer initiation, while both advantageous and disadvantageous mutations can accelerate the process . The probability and timing of cancer initiation can vary significantly, and understanding these dynamics is crucial for developing preventive strategies .
Tumor Progression and Metastasis
After the initial formation of a tumor, cancer cells can invade surrounding tissues and spread to distant sites in the body, a process known as metastasis. This involves several steps, including invasion of local tissues, intravasation into blood vessels, circulation through the bloodstream, extravasation into new tissues, and growth at secondary sites . Metastasis is responsible for the majority of cancer-related deaths.
Physical Traits of Tumors
The physical properties of tumors, such as solid stress, interstitial fluid pressure, and tissue stiffness, also play a significant role in cancer progression. These physical traits can impair blood flow, promote tumor invasiveness, and contribute to treatment resistance. Understanding these physical aspects is essential for developing new therapeutic strategies.
Conclusion
Cancer starts with genetic mutations that disrupt normal cell functions, leading to uncontrolled growth and tumor formation. The process involves clonal selection, inactivation of DNA repair genes, and dynamic mutation accumulation. As the tumor progresses, it can invade surrounding tissues and metastasize to distant sites, driven by both genetic and physical factors. Understanding these mechanisms is crucial for developing effective cancer prevention and treatment strategies.
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