Changes

==Treatment of cancer==

==Treatment of cancer==

===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.

===radiation therapy===

===Radiation therapy===

Radiation therapy involves the use of precisely-targeted [[radiation]] to destroy cancer cells.  Because radiation damages [[DNA]] and thus has the ability both to treat and to cause cancer, this method of treatment must be administered by physicians highly-skilled in [[physics]].

Radiation therapy involves the use of precisely-targeted [[radiation]] to destroy cancer cells.  Because radiation damages [[DNA]] and thus has the ability both to treat and to cause cancer, this method of treatment must be administered by physicians highly-skilled in [[physics]].

===surgery===

===Surgery===

The goal of cancer surgery is to physically remove the abnormal cells.  This becomes more difficult after the cancer spreads.  Often, chemotherapy is used either before or after surgery to kill cancer cells that have [[metastasis|metastasized]].

The goal of cancer surgery is to physically remove the abnormal cells.  This becomes more difficult after the cancer spreads.  Often, chemotherapy is used either before or after surgery to kill cancer cells that have [[metastasis|metastasized]].

===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.

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.

===New and Experimental Treatments===

===New and Experimental Treatments===