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KEY POINTS
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The term cancer describes a subset of neoplastic lesions.
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A neoplasm is defined as a heritably altered, relatively autonomous growth of tissue with abnormal regulation of gene expression.
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Metastases are secondary growths of cells from the primary neoplasm.
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A carcinogen is an agent whose administration to previously untreated animals leads to a statistically significant increased incidence of neoplasms of one or more histogenetic types as compared with the incidence in appropriate untreated animals.
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Initiation requires one or more rounds of cell division for the “fixation” of the DNA damage.
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Promotion results from the selective functional enhancement of the initiated cell and its progeny by the continuous exposure to the promoting agent.
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Progression is the transition from early progeny of initiated cells to the biologically malignant cell population of the neoplasm.
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Cancer is a disease characterized by genomic mutation, modified gene expression, cell proliferation, and aberrant cell growth. It is one of the leading causes of death in the world. Multiple causes of cancer include infectious agents, radiation, and chemicals. Estimates suggest that 70% to 90% of all human cancers have a link to environmental, dietary, and behavioral factors.
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Neoplasia is defined as new growth or autonomous growth of tissue. A neoplastic lesion is referred to as a neoplasm (Table 8–1).
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For benign neoplasms, the tissue of origin is frequently followed by the suffix “oma”; for example, a benign fibrous neoplasm would be termed fibroma, and a benign glandular epithelium termed an adenoma. Malignant neoplasms from epithelial origin are called carcinoma while those derived from mesenchymal origin are referred to as sarcoma. Thus, a malignant neoplasm of fibrous tissue would be a fibrosarcoma while that derived from bone would be an osteosarcoma.
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The term cancer describes a subset of neoplasia that represents malignant neoplasms. Carcinogens that induce cancer include chemicals, viruses, hormones, radiation, or solid materials. Genotoxic carcinogens interact with DNA to damage or change its structure. Non-genotoxic carcinogens do not directly interact with nuclear DNA, but may change gene expression, modify normal cell function, bind to or modify cellular receptors, or increase the number of cells in ...