Editing Cancer (section)

=== Chemotherapy ===
[[Chemotherapy]] is the treatment of cancer with one or more [[Cytotoxicity|cytotoxic]] anti-[[neoplastic]] drugs ([[list of chemotherapeutic agents|chemotherapeutic agents]]) as part of a [[chemotherapy regimen|standardized regimen]]. The term encompasses a variety of drugs, which are divided into broad categories such as [[Alkylating antineoplastic agent|alkylating agents]] and [[antimetabolite]]s.<ref name="Lind2008">{{cite journal | vauthors = Lind MJ |title=Principles of cytotoxic chemotherapy |journal=Medicine |year=2008 |volume=36 |issue=1 |pages=19–23 |doi=10.1016/j.mpmed.2007.10.003 }}</ref> Traditional chemotherapeutic agents act by killing cells that divide rapidly, a critical property of most cancer cells.

It was found that providing combined cytotoxic drugs is better than a single drug, a process called the [[combination therapy]], which has an advantage in the statistics of survival and response to the tumor and in the progress of the disease.<ref>{{cite book | vauthors = Frei III E, Eder JP |title=Combination Chemotherapy |date=2003 |url=https://www.ncbi.nlm.nih.gov/books/NBK13955/ |access-date=4 April 2020 |language=en}}</ref> A Cochrane review concluded that combined therapy was more effective in treating metastasized breast cancer. However, generally it is not certain whether combination chemotherapy leads to better health outcomes, when both survival and toxicity are considered.<ref>{{cite journal | vauthors = Dear RF, McGeechan K, Jenkins MC, Barratt A, Tattersall MH, Wilcken N | title = Combination versus sequential single agent chemotherapy for metastatic breast cancer | journal = The Cochrane Database of Systematic Reviews | issue = 12 | pages = CD008792 | date = December 2013 | volume = 2021 | pmid = 24347031 | doi = 10.1002/14651858.CD008792.pub2 | pmc = 8094913 }}</ref>

[[Targeted therapy]] is a form of chemotherapy that targets specific molecular differences between cancer and normal cells. The first targeted therapies blocked the [[estrogen receptor]] molecule, inhibiting the growth of breast cancer. Another common example is the class of [[Bcr-Abl tyrosine-kinase inhibitor|Bcr-Abl inhibitors]], which are used to treat [[chronic myelogenous leukemia]] (CML).<ref name=TCT2018/> Currently, targeted therapies exist for many of the most common cancer types, including [[bladder cancer]], breast cancer, [[colorectal cancer]], [[kidney cancer]], [[leukemia]], [[liver cancer]], lung cancer, [[lymphoma]], [[pancreatic cancer]], [[prostate cancer]], [[skin cancer]], and [[thyroid cancer]] as well as other cancer types.<ref name=TCT2018/>

The efficacy of chemotherapy depends on the type of cancer and the stage. In combination with surgery, chemotherapy has proven useful in cancer types including breast cancer, colorectal cancer, [[pancreatic cancer]], [[osteosarcoma|osteogenic sarcoma]], [[testicular cancer]], ovarian cancer and certain lung cancers.<ref name=HollandTx40/> Chemotherapy is curative for some cancers, such as some [[leukemias]],<ref>{{cite journal |vauthors=Nastoupil LJ, Rose AC, Flowers CR |title=Diffuse large B-cell lymphoma: current treatment approaches |journal=Oncology |volume=26 |issue=5 |pages=488–95 |date=May 2012 |pmid=22730604}}</ref><ref>{{cite journal |vauthors=Freedman A |title=Follicular lymphoma: 2012 update on diagnosis and management |journal=American Journal of Hematology |volume=87 |issue=10 |pages=988–95 |date=October 2012 |pmid=23001911 |doi=10.1002/ajh.23313|s2cid=35447562 |doi-access=free }}</ref> ineffective in some [[brain tumors]],<ref>{{cite journal |vauthors=Rampling R, James A, Papanastassiou V |title=The present and future management of malignant brain tumours: surgery, radiotherapy, chemotherapy |journal=Journal of Neurology, Neurosurgery, and Psychiatry |volume=75 |issue=Suppl 2 |pages=ii24–30 |date=June 2004 |pmid=15146036 |pmc=1765659 |doi=10.1136/jnnp.2004.040535}}</ref> and needless in others, such as most [[non-melanoma skin cancer]]s.<ref>{{cite journal |vauthors=Madan V, Lear JT, Szeimies RM |title=Non-melanoma skin cancer |journal=Lancet |volume=375 |issue=9715 |pages=673–85 |date=February 2010 |pmid=20171403 |doi=10.1016/S0140-6736(09)61196-X|pmc=3339125 }}</ref> The effectiveness of chemotherapy is often limited by its toxicity to other tissues in the body. Even when chemotherapy does not provide a permanent cure, it may be useful to reduce symptoms such as pain or to reduce the size of an inoperable tumor in the hope that surgery will become possible in the future.{{Citation needed|date=January 2025}}