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Week_4_-_Carcinogenesis - Week 4 Carcinogenesis Cancer...

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Week 4 - Carcinogenesis Cancer Cancer has long been considered a cellular disease since cancers are composed of cells that grow without restraint in various areas of the body. Such growths of cancerous cells can replace normal cells or tissues causing severe malformations (such as with skin and bone cancers) and failure of internal organs which frequently leads to death. How do cells become cancerous? Development of cancer is an enormously complex process. Once a cell has started on the cancer path, it progresses through a series of steps, which continue long after the initial cause has disappeared. There are about as many types of cancers as there are different types of cells in the body (over 100 types) . Some cell types constantly divide and are replaced (such as skin and blood cells) . Other types of cells rarely or never divide (such as bone cells and neurons) . Sophisticated mechanisms exist in cells to control when, if, and how cells replicate. Cancer occurs when these mechanisms are lost and replication takes place in an uncontrolled and disorderly manner. A cancer is generally considered to arise from a single cell that goes bad. Recent research has begun to unravel the extremely complex pathogenesis of cancer. Underlying the progression of cancer that changes (transforms) normal cells to cancerous cells is an intricate array of biochemical changes that take place within cells and between cells. These biochemical changes lead a cell through a series of steps, changing it gradually from a normal to a cancer cell. The altered cell is no longer bound by the regulatory controls that govern the life and behavior of normal cells. Cancer is not a single disease but a large group of diseases. The common aspects are that all cancers have the same basic property - they are composed of 'cells gone wild'. Cancer cells do not conform to the usual constraints on cell proliferation - they grow uncontrolledly. Cancer Terminology Listed below are definitions for the most frequently used cancer terms: cancer a malignant tumor that has the ability to metastasize or invade into surrounding tissue tumor a general term for the uncontrolled growth of cells that becomes progressively larger with time; tumors may be benign or malignant neoplasm same as tumor neoplasia the growth of new tissue with abnormal and unregulated cellular proliferation benign tumor a tumor that does not metastasize or invade surrounding tissue malignant tumor a tumor that has the ability to metastasize or invade surrounding tissue (same as tumor) metastasis ability to establish secondary tumor growth at a new location away from the original site carcinogenesis the production of a carcinoma (epithelial cell cancer); general term used to
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describe the production of any type of tumor Most malignant tumors fall into one of two categories, carcinomas or sarcomas. The
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Week_4_-_Carcinogenesis - Week 4 Carcinogenesis Cancer...

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