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Encyclopedia > Tumor

Tumor or tumour (via Old French tumour from Latin tumor "swelling") is an abnormal growth or mass of tissue. A tumor can be either malignant or benign. Nearly all tumors are examples of neoplasia, although certain developmental malformations or inflammatory masses may occasionally be referred to as tumors. Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Old French was the Romance dialect continuum spoken in territories corresponding roughly to the northern half of modern France and parts of modern Belgium and Switzerland from around 1000 to 1300. ... For other uses, see Latin (disambiguation). ... Biological tissue is a collection of interconnected cells that perform a similar function within an organism. ... For other uses, see Cancer (disambiguation). ... Tumor (American English) or tumour (British English) originally means swelling, and is sometimes still used with that meaning. ... Neoplasia (new growth in Greek) is abnormal proliferation of cells in a tissue or organ. ... A hamartoma is a common benign tumor in an organ composed of tissue elements normally found at that site but that are growing in a disorganized mass. ... An abscess on the skin, showing the redness and swelling characteristic of inflammation. ...


Causes

Neoplastic tumors are caused by mutations in DNA of cells, which interfere with a cell's ability to regulate and limit cell division. An accumulation of mutations is needed for a tumor to emerge. Mutations that activate oncogenes or repress tumor suppressor genes can eventually lead to tumors. Cells have mechanisms that repair DNA and other mechanisms that cause the cell to destroy itself by apoptosis if DNA damage gets too severe. Mutations that repress the genes for these mechanisms can also eventually lead to cancer. A mutation in one oncogene or one tumor repressor gene is usually not enough for a tumor to occur. A combination of a number of mutations is necessary. It has been suggested that mutant be merged into this article or section. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... This does not adequately cite its references or sources. ... An oncogene is a modified gene that increases the malignancy of a tumor cell. ... A tumor suppressor gene is a gene that reduces the probability that a cell in a multicellular organism will turn into a tumor cell. ... A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ...


More recently, it has emerged that some human cancers, particularly epithelial cancers, are caused by virus infection. One common group of cancer-causing viruses are members of the Herpesvirus family, which can cause cancers such as Kaposi Sarcoma. A recent vaccine for the causative agent of many forms of genital warts, human papillomavirus (HPV), was publicised as a vaccine against cervical cancer, as HPV causes nearly all primary cervical cancers. Genera Subfamily Alphaherpesvirinae    Simplexvirus    Varicellovirus    Mardivirus    Iltovirus Subfamily Betaherpesvirinae    Cytomegalovirus    Muromegalovirus    Roseolovirus Subfamily Gammaherpesvirinae    Lymphocryptovirus    Rhadinovirus Unassigned    Ictalurivirus The Herpesviridae are a family of DNA viruses that cause diseases in humans and animals. ... “HPV” redirects here. ...


DNA microarrays can be used to determine if the expression of oncogenes or tumor repressor genes has been altered. Possibly in the future tumors can be treated better by using DNA microarrays to determine the exact characteristics of the tumor. It has been suggested that Gene chip technology be merged into this article or section. ...


See also

For the server security software, see Microsoft Forefront. ... Tumor markers are substances found in the blood, urine or body tissues that can be elevated in cancer. ...

References

  • Ramzi Cotran, Vinay Kumar, Tucker Collins (1999). Robbins Pathologic Basis of Disease, Sixth Edition. W.B. Saunders. ISBN 072167335X. 

  Results from FactBites:
 
Tumor - Wikipedia, the free encyclopedia (1071 words)
Tumor meaning swelling is one of the five classical characteristics of inflammation.
This means that the prevalence of tumors increases strongly with increasing age.
Tumors are caused by mutations in DNA of cells.
Encyclopedia4U - Brain tumor - Encyclopedia Article (825 words)
A brain tumor is a mass created by abnormal and uncontrolled growth of cells either found in the brain (neurons, glial cells, epithelial cells, myelin producing cells etc.) (primary brain tumors) or originating in another part of the body and spreading to the brain (secondary brain tumors or metastatic brain tumors).
Primary or secondary, brain tumors may cause herniation of the brain (displacement of one part of the brain tissue due to mass effect of a lesion, usually causing the compression of the neurons controlling the respiratory system in the brainstem and eventually death) and permanent neurologic changes including intellectual decline.
Tumors may affect brain cells from a distance by consuming too much food and energy that is crucial for neurons, by secreting endocrine substances altering nerve cell functions or in the majority of the cases by causing the immune system of the body to develop antibodies (autoantibodies) directed against nerve cells.
  More results at FactBites »

 
 

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