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Pathology - Carcinogenesis
Definition • The series of events culminating in the formation of a malignant tumor.
Aetiology
• Radiation or chemicals that impair DNA, such as sunlight in skin carcinomas and cigarette smoke in lung carcinomas. Chronic inflammatory illnesses that induce sustained cellular proliferation, such as ulcerative colitis, increase the risk of colonic cancer
.• Elevated hormone levels induce the proliferation of hormonally responsive tissues, such as estrogens in breast and endometrial carcinomas. Oncogenic viruses synthesize proteins that facilitate unregulated cell proliferation, such as HPV in cervical cancer. Pathogenesis DNA damage to genes encoding proteins that govern cell division permits uncontrolled cellular proliferation. Genes regulating cell division are categorized into oncogenes and tumor suppressor genes. Oncogenes are mutated genes that facilitate cell division. Mutations typically lead to the overexpression of the gene product or the constitutive activation of the protein product. Examples of oncogenes frequently mutated in malignancies are KIT, RAS, and MYC.
Tumor suppressor genes
• Genes that encode proteins which typically decrease cellular proliferation. • Typically, the inactivation of both alleles is necessary for a tumorigenic impact. Examples of frequently altered tumour suppressor genes in malignancies include P53, CDKN2A, and RB
Metastasis
• The attainment of metastatic capability is a crucial occurrence in the progression of a neoplasm; dissemination to remote locations is a primary factor contributing to the mortality associated with malignant tumors. Malignant neoplasms disseminate through three primary pathways: hematogenous spread to distant organs (e.g., lungs, liver, bone, brain), lymphatic spread to regional lymph nodes (e.g., axillary lymph nodes in breast carcinomas), and transcoelomic spread, wherein malignant tumors adjacent to body cavities, such as the pleura or peritoneum, can infiltrate these spaces and propagate to other organs. Successful metastasis necessitates the malignant cells to surmount several obstacles: detachment from adjacent cells, degradation of the extracellular matrix, invasion of a vessel lumen, endurance in circulation while reaching a distant location, egress from the vessel, and effective implantation and proliferation at the new site.
Definition • The series of events culminating in the formation of a malignant tumor.
Aetiology
• Radiation or chemicals that impair DNA, such as sunlight in skin carcinomas and cigarette smoke in lung carcinomas. Chronic inflammatory illnesses that induce sustained cellular proliferation, such as ulcerative colitis, increase the risk of colonic cancer
.• Elevated hormone levels induce the proliferation of hormonally responsive tissues, such as estrogens in breast and endometrial carcinomas. Oncogenic viruses synthesize proteins that facilitate unregulated cell proliferation, such as HPV in cervical cancer. Pathogenesis DNA damage to genes encoding proteins that govern cell division permits uncontrolled cellular proliferation. Genes regulating cell division are categorized into oncogenes and tumor suppressor genes. Oncogenes are mutated genes that facilitate cell division. Mutations typically lead to the overexpression of the gene product or the constitutive activation of the protein product. Examples of oncogenes frequently mutated in malignancies are KIT, RAS, and MYC.
Tumor suppressor genes
• Genes that encode proteins which typically decrease cellular proliferation. • Typically, the inactivation of both alleles is necessary for a tumorigenic impact. Examples of frequently altered tumour suppressor genes in malignancies include P53, CDKN2A, and RB
Metastasis
• The attainment of metastatic capability is a crucial occurrence in the progression of a neoplasm; dissemination to remote locations is a primary factor contributing to the mortality associated with malignant tumors. Malignant neoplasms disseminate through three primary pathways: hematogenous spread to distant organs (e.g., lungs, liver, bone, brain), lymphatic spread to regional lymph nodes (e.g., axillary lymph nodes in breast carcinomas), and transcoelomic spread, wherein malignant tumors adjacent to body cavities, such as the pleura or peritoneum, can infiltrate these spaces and propagate to other organs. Successful metastasis necessitates the malignant cells to surmount several obstacles: detachment from adjacent cells, degradation of the extracellular matrix, invasion of a vessel lumen, endurance in circulation while reaching a distant location, egress from the vessel, and effective implantation and proliferation at the new site.
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