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The term '''cancer''' refers to many different diseases. They all have in common uncontrolled ''cell [[proliferation]]'' (growth and division). Cancers are usually named for the organ or cell type that is originally involved. After beginning at one site, cancer may ''metastasize'' (spread) to other organs. The cancer is still named by its place of origin.
The term '''cancer''' refers to many different diseases. They all have in common uncontrolled ''cell [[proliferation]]'' (growth and division). Cancers are usually named for the organ or cell type that is originally involved. After beginning at one site, the cancerous cells may ''metastasize'' (spread) to other organs and then continue to grow, causing more damage in the new location as well. The cancer is still named by its place of origin.
All known carcinogens (cancer-inducing agents), which include various chemicals, viruses, and ionizing radiation, act by breaking chemical bonds to produce [[DNA]] [[mutations]]." [http://www.livescience.com/health/cell-phone-radiation-cancer-100118.html] These mutations occur randomly throughout the genome, and if not repaired by the cell's DNA repair mechanisms, they can impede normal cellular functions. If enough unrepaired mutations occur in genes associated with cell growth, this can cause the cells to grow when they should not.
==Types of Cancer==
==Types of Cancer==
==Treatment of cancer==
==Treatment of cancer==
Cancer treatment requires destruction or removal of cancerous cells with minimal effect to healthy cells. Since the cancerous cells are descended from healthy cells and are thus very similar to them, this is very difficult. Furthermore, the small differences are dependent on what mutations initially caused the cancer in the first place, so most treatments are only effective against a certain percentage of cancers from any one tissue.
===Chemotherapy===
===Chemotherapy===
[[Chemotherapy]] is the use of drugs that kill [[tumor]] cells. Conventionally, the drugs that are used are those that target cells which are rapidly undergoing [[mitosis]]; this approach is effective but is limited by side effects, which occur because these drugs have an adverse effect on normal tissues that contain rapidly-dividing cells. Research is under way to find drugs with a wider [[therapeutic index]]. One approach is to study specific molecular markers that may be used to identify cancer cells, and to develop drugs that preferentially kill cells that exhibit those markers.
[[Chemotherapy]] is the use of drugs that kill [[tumor]] cells. Conventionally, the drugs that are used are those that target cells which are rapidly undergoing [[mitosis]]; this approach is effective but is limited by side effects, which occur because these drugs have an adverse effect on normal tissues that contain rapidly-dividing cells. Research is under way to find drugs with a wider [[therapeutic index]]. One approach is to study specific molecular markers that may be used to identify cancer cells, and to develop drugs that preferentially kill cells that exhibit those markers.
An example of chemotherapy is dichloroacetate (DCA), a chemical with the formula: CHCl₂COOH. DCA cures cancer by restoring the mitochondria of cancer cells. Cancer cells use glycolysis to produce energy since the mitochondria is damaged and there is not enough oxygen (see. [[Hypoxia]]) to go through respiration (oxidative phosphorylation)<ref>{{cite journal |author=Xu R, Pelicano H, Zhou Y, Carew J, Feng L, Bhalla K, Keating M, Huang P |title=Inhibition of glycolysis in cancer cells: a novel strategy to overcome drug resistance associated with mitochondrial respiratory defect and hypoxia |journal=Cancer Res |volume=65 |issue=2 |pages=613–21 |year=2005 |pmid=15695406}}</ref>. Usually cells with a critical amount of damage (such as in cancer cells) kill themselves by [[apoptosis]] which requires properly functioning mitochondria. DCA restores the function of the mitochondria and thus apoptosis is restored. Cancer cells then begin killing themselves off.
DCA is available for purchase from websites and physicians, although it is still in the human testing trials in Canada. The trials have proved promising, but this off-label use of DCA to treat cancer has sparked lots of controversy. Most chemotherapy treatments are not so controversial, since they have undergone much more testing to guarantee their safety.
===Radiation therapy===
===Radiation therapy===
===Immunotherapy===
===Immunotherapy===
The immune system contains a number of cell types, such as [[NK cells]] and [[cytotoxic T cell|killer T cells]] that have the capability to destroy other cells that have become infected with viruses or have become cancerous. [[Immunotherapy]] involves the enhancement or potentiation of these natural defenses against tumor cells. A common procedure is to remove immature immune cells from the patient's [[bone marrow]], purify the T-cells and expose them to [[antigen]]s from the tumor. The activated cells are then re-injected, allowing them to seek out cancerous tissues.
The immune system contains a number of cell types, such as [[NK cells]] and [[cytotoxic T cell|killer T cells]] that have the capability to destroy other cells that have become infected with viruses or have become cancerous. [[Immunotherapy]] involves the enhancement or potentiation of these natural defenses against tumor cells. This is useful because some cancer cells may have mutations that make it hard for the immune system to recognize them as abnormal. A common procedure is to remove immature immune cells from the patient's [[bone marrow]], purify the T-cells and expose them to [[antigen]]s from the tumor. The activated cells are then re-injected, allowing them to seek out cancerous tissues.
== See also ==
== See also ==