Editing Cancer (section)

=== Radiation ===
[[Radiation therapy]] involves the use of [[ionizing radiation]] in an attempt to either cure or improve symptoms.<!--<ref name=H41/> --> It works by damaging the DNA of cancerous tissue, causing [[mitotic catastrophe]] resulting in the death of the cancer cells.<ref>{{cite journal | vauthors = Vitale I, Galluzzi L, Castedo M, Kroemer G | title = Mitotic catastrophe: a mechanism for avoiding genomic instability | journal = Nature Reviews. Molecular Cell Biology | volume = 12 | issue = 6 | pages = 385–392 | date = June 2011 | pmid = 21527953 | doi = 10.1038/nrm3115 | s2cid = 22483746 }}</ref> To spare normal tissues (such as skin or organs, which radiation must pass through to treat the tumor), shaped radiation beams are aimed from multiple exposure angles to intersect at the tumor, providing a much larger dose there than in the surrounding, healthy tissue. As with chemotherapy, cancers vary in their response to radiation therapy.<ref>{{cite book | vauthors = Bomford CK, Kunkler IH, Walter J | title = Walter and Miller's Textbook of Radiation therapy | edition = 6th | page = 311 }}</ref><ref>{{cite web |url=http://www.gpnotebook.co.uk/simplepage.cfm?ID=2060451853 |title=tumour radiosensitivity – General Practice Notebook | vauthors =  McMorran J, Crowther D, McMorran S, Youngmin S, Wacogne I, Pleat J, Clive P |url-status=live |archive-url=https://web.archive.org/web/20150924023421/http://www.gpnotebook.co.uk/simplepage.cfm?ID=2060451853 |archive-date=24 September 2015}}</ref><ref>{{cite web |url=https://patient.info/doctor/radiotherapy-pro |title=Radiotherapy |publisher=[[Patient UK]] | vauthors = Tidy C |date=23 December 2015 | url-status = live |archive-url=https://web.archive.org/web/20170709084620/https://patient.info/doctor/radiotherapy-pro |archive-date=9 July 2017}} Last Checked: 23 December 2015</ref>

Radiation therapy is used in about half of cases. The radiation can be either from internal sources ([[brachytherapy]]) or external sources. The radiation is most commonly low energy X-rays for treating skin cancers, while higher energy X-rays are used for cancers within the body.<ref>{{cite journal |vauthors=Hill R, Healy B, Holloway L, Kuncic Z, Thwaites D, Baldock C |s2cid=18082594 |title=Advances in kilovoltage x-ray beam dosimetry |journal=Physics in Medicine and Biology |volume=59 |issue=6 |pages=R183–231 |date=March 2014 |pmid=24584183 |doi=10.1088/0031-9155/59/6/r183|bibcode=2014PMB....59R.183H }}</ref> Radiation is typically used in addition to surgery and/or chemotherapy. For certain types of cancer, such as early [[head and neck cancer]], it may be used alone.<ref name=H41/> Radiation therapy after surgery for brain metastases has been shown to not improve overall survival in patients compared to surgery alone.<ref>{{Cite web |date=13 August 2019 |title=Radiation Therapy for Brain Metastases: A Systematic Review |url=https://www.pcori.org/research-results/2019/radiation-therapy-brain-metastases-systematic-review |access-date=10 October 2023 |website=PCORI |language=en}}</ref> For painful [[bone metastasis]], radiation therapy has been found to be effective in about 70% of patients.<ref name="H41">Holland Chp. 41</ref>