Editing Cancer (section)

== Prevention ==
{{Main|Cancer prevention}}
[[File:Global deaths from cancers attributable to risk factors in 2019 by sex and SDI.jpg|thumb|upright=1.15 |Global deaths from cancers attributable to risk factors in 2019 by sex and {{tooltip|Socio-demographic Index|a measure of a location's socio-demographic development that takes into account average income per person, educational attainment, and total fertility rate}}.<ref name="10.1016/S0140-6736(22)01438-6"/>]]
[[File:Cancer DALYs attributable to 11 Level 2 risk factors globally in 2019.jpg|thumb|upright=1.15|Cancer [[DALY]]s attributable to 11 Level 2 risk factors globally in 2019.<ref name="10.1016/S0140-6736(22)01438-6"/>]]
Cancer prevention is defined as active measures to decrease cancer risk.<ref>{{cite web |title=Cancer prevention: 7 steps to reduce your risk |publisher=[[Mayo Clinic]] |url=http://www.mayoclinic.com/health/cancer-prevention/CA00024 |date=27 September 2008 |access-date=30 January 2010 |url-status=live |archive-url=https://web.archive.org/web/20100208082208/http://www.mayoclinic.com/health/cancer-prevention/CA00024 |archive-date=8 February 2010}}</ref> The vast majority of cancer cases are due to environmental risk factors. Many of these environmental factors are controllable lifestyle choices. Thus, cancer is generally preventable.<ref name=Danaei>{{cite journal |vauthors=Danaei G, Vander Hoorn S, Lopez AD, Murray CJ, Ezzati M |s2cid=17354479 |title=Causes of cancer in the world: comparative risk assessment of nine behavioural and environmental risk factors |journal=Lancet |volume=366 |issue=9499 |pages=1784–93 |date=November 2005 |pmid=16298215 |doi=10.1016/S0140-6736(05)67725-2|doi-access=free }}</ref> Between 70% and 90% of common cancers are due to environmental factors and therefore potentially preventable.<ref>{{cite journal |vauthors=Wu S, Powers S, Zhu W, Hannun YA |title=Substantial contribution of extrinsic risk factors to cancer development |journal=Nature |volume=529 |issue=7584 |pages=43–7 |date=January 2016 |pmid=26675728 |pmc=4836858 |doi=10.1038/nature16166 |bibcode=2016Natur.529...43W}}</ref>

Greater than 30% of cancer deaths could be prevented by avoiding risk factors including: tobacco, [[overweight|excess weight]]/[[obesity]], poor diet, [[physical inactivity]], [[alcohol (drug)|alcohol]], [[sexually transmitted infection]]s and air pollution.<ref name="Cancer Cancer">{{cite web |url=https://www.who.int/mediacentre/factsheets/fs297/en/ |title=Cancer |website=World Health Organization |access-date=9 January 2011 |url-status=live |archive-url=https://web.archive.org/web/20101229092321/http://www.who.int/mediacentre/factsheets/fs297/en/ |archive-date=29 December 2010}}</ref> Further, poverty could be considered as an indirect risk factor in human cancers.<ref>{{cite journal | vauthors = Heidary F, Rahimi A, Gharebaghi R | title = Poverty as a risk factor in human cancers | journal = Iranian Journal of Public Health | volume = 42 | issue = 3 | pages = 341–343 | date = 2013 | pmid = 23641414 | pmc = 3633807 }}</ref> Not all environmental causes are controllable, such as naturally occurring [[background radiation]] and cancers caused through hereditary [[genetic disorders]] and thus are not preventable via personal behavior.

In 2019, ~44% of all cancer deaths – or ~4.5 M deaths or ~105 million lost [[disability-adjusted life year]]s – were [[List of causes of death by rate#Underlying causes|due to known clearly preventable risk factors]]<!--(causal-contributing factors)-->, led by [[smoking]], [[Health effects of alcohol|alcohol use]] and [[obesity|high BMI]], according to a [[Global Burden of Disease Study|GBD]] [[Systematic review|systematic analysis]].<ref name="10.1016/S0140-6736(22)01438-6">{{cite journal | vauthors = Tran KB, Lang JJ, Compton K, Xu R, Acheson AR, Henrikson HJ, etal | title = The global burden of cancer attributable to risk factors, 2010-19: a systematic analysis for the Global Burden of Disease Study 2019 | language = English | journal = Lancet | volume = 400 | issue = 10352 | pages = 563–591 | date = August 2022 | pmid = 35988567 | pmc = 9395583 | doi = 10.1016/S0140-6736(22)01438-6 | doi-access = free }}</ref>

=== Dietary ===
{{Main|Diet and cancer}}
While many dietary recommendations have been proposed to reduce cancer risks, the evidence to support them is not definitive.<ref name=Kushi2012/><ref name=Diet11>{{cite journal |vauthors=Wicki A, Hagmann J |title=Diet and cancer |journal=[[Swiss Medical Weekly]] |volume=141 |pages=w13250 |date=September 2011 |pmid=21904992 |doi=10.4414/smw.2011.13250|doi-access=free }}</ref> The primary dietary factors that increase risk are [[obesity]] and alcohol consumption. Diets low in fruits and vegetables and high in red meat have been implicated but reviews and meta-analyses do not come to a consistent conclusion.<ref name="pmid22202045">{{cite journal |vauthors=Cappellani A, Di Vita M, Zanghi A, Cavallaro A, Piccolo G, Veroux M, Berretta M, Malaguarnera M, Canzonieri V, Lo Menzo E |title=Diet, obesity and breast cancer: an update |journal=Frontiers in Bioscience |volume=4 |pages=90–108 |date=January 2012 |issue=1 |pmid=22202045 |doi=10.2741/253}}</ref><ref name="pmid21119663">{{cite journal |vauthors=Key TJ |title=Fruit and vegetables and cancer risk |journal=British Journal of Cancer |volume=104 |issue=1 |pages=6–11 |date=January 2011 |pmid=21119663 |pmc=3039795 |doi=10.1038/sj.bjc.6606032}}</ref> A 2014 meta-analysis found no relationship between fruits and vegetables and cancer.<ref>{{cite journal |vauthors=Wang X, Ouyang Y, Liu J, Zhu M, Zhao G, Bao W, Hu FB |title=Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies |journal=BMJ |volume=349 |pages=g4490 |date=July 2014 |pmid=25073782 |pmc=4115152 |doi=10.1136/bmj.g4490}}</ref> Coffee is associated with a reduced risk of [[liver cancer]].<ref name="pmid17484871">{{cite journal |vauthors=Larsson SC, Wolk A |title=Coffee consumption and risk of liver cancer: a meta-analysis |journal=Gastroenterology |volume=132 |issue=5 |pages=1740–5 |date=May 2007 |pmid=17484871 |doi=10.1053/j.gastro.2007.03.044|url=http://www.gastrojournal.org/article/S0016508507005689/pdf |doi-access=free }}</ref> Studies have linked excessive consumption of [[red meat|red]] or [[processed meat]] to an increased risk of breast cancer, [[Colorectal cancer|colon cancer]] and [[pancreatic cancer]], a phenomenon that could be due to the presence of [[carcinogens]] in meats cooked at high temperatures.<ref name="pmid19838915">{{cite journal |vauthors=Zheng W, Lee SA |title=Well-done meat intake, heterocyclic amine exposure, and cancer risk |journal=Nutrition and Cancer |volume=61 |issue=4 |pages=437–46 |year=2009 |pmid=19838915 |pmc=2769029 |doi=10.1080/01635580802710741}}</ref><ref name="pmid20374790">{{cite journal |vauthors=Ferguson LR |title=Meat and cancer |journal=Meat Science |volume=84 |issue=2 |pages=308–13 |date=February 2010 |pmid=20374790 |doi=10.1016/j.meatsci.2009.06.032}}</ref> In 2015 the [[International Agency for Research on Cancer|IARC]] reported that eating [[processed meat]] (e.g., [[bacon]], [[ham]], [[hot dogs]], [[sausages]]) and, to a lesser degree, [[red meat]] was linked to some cancers.<ref name="WHO-20151026">{{cite news |author=Staff |title=World Health Organization – IARC Monographs evaluate consumption of red meat and processed meat |url=http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf |date=26 October 2015 |work=[[International Agency for Research on Cancer]] |access-date=26 October 2015 |url-status=live |archive-url=https://web.archive.org/web/20151026144543/http://www.iarc.fr/en/media-centre/pr/2015/pdfs/pr240_E.pdf |archive-date=26 October 2015}}</ref><ref name="NYT-20151026">{{cite news | vauthors = Hauser C |title=W.H.O. Report Links Some Cancers With Processed or Red Meat |url=https://www.nytimes.com/2015/10/27/health/report-links-some-types-of-cancer-with-processed-or-red-meat.html |date=26 October 2015 |work=[[The New York Times]] |access-date=26 October 2015 |url-status=live |archive-url=https://web.archive.org/web/20151026173834/http://www.nytimes.com/2015/10/27/health/report-links-some-types-of-cancer-with-processed-or-red-meat.html |archive-date=26 October 2015}}</ref>

[[Healthy diet|Dietary recommendations]] for cancer prevention typically include an emphasis on vegetables, fruit, [[whole grains]] and fish and an avoidance of processed and red meat (beef, pork, lamb), [[animal fats]], [[pickled foods]] and [[Carbohydrate#Nutrition|refined carbohydrates]].<ref name=Kushi2012/><ref name=Diet11/>

=== Medication ===
Medications can be used to prevent cancer in a few circumstances.<ref>Holland Chp.33</ref> In the general population, [[Non-steroidal anti-inflammatory drug|NSAIDs]] reduce the risk of [[colorectal cancer]]; however, due to cardiovascular and gastrointestinal side effects, they cause overall harm when used for prevention.<ref name="pmid17339623">{{cite journal |vauthors=Rostom A, Dubé C, Lewin G, Tsertsvadze A, Barrowman N, Code C, Sampson M, Moher D |title=Nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors for primary prevention of colorectal cancer: a systematic review prepared for the U.S. Preventive Services Task Force |journal=Annals of Internal Medicine |volume=146 |issue=5 |pages=376–89 |date=March 2007 |pmid=17339623 |doi=10.7326/0003-4819-146-5-200703060-00010|doi-access=free }}</ref> [[Aspirin]] has been found to reduce the risk of death from cancer by about 7%.<ref name="pmid21144578">{{cite journal |vauthors=Rothwell PM, Fowkes FG, Belch JF, Ogawa H, Warlow CP, Meade TW |s2cid=22950940 |title=Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials |journal=Lancet |volume=377 |issue=9759 |pages=31–41 |date=January 2011 |pmid=21144578 |doi=10.1016/S0140-6736(10)62110-1}}</ref> [[COX-2 inhibitor]]s may decrease the rate of [[polyp (medicine)|polyp]] formation in people with [[familial adenomatous polyposis]]; however, it is associated with the same adverse effects as NSAIDs.<ref name="pmid20594533">{{cite journal |vauthors=Cooper K, Squires H, Carroll C, Papaioannou D, Booth A, Logan RF, Maguire C, Hind D, Tappenden P |title=Chemoprevention of colorectal cancer: systematic review and economic evaluation |journal=Health Technology Assessment |volume=14 |issue=32 |pages=1–206 |date=June 2010 |pmid=20594533 |doi=10.3310/hta14320|doi-access=free }}</ref> Daily use of [[tamoxifen]] or [[raloxifene]] reduce the risk of breast cancer in high-risk women.<ref name="pmid19020189">{{cite journal |vauthors=Thomsen A, Kolesar JM |title=Chemoprevention of breast cancer |journal=American Journal of Health-System Pharmacy |volume=65 |issue=23 |pages=2221–28 |date=December 2008 |pmid=19020189 |doi=10.2146/ajhp070663}}</ref> The benefit versus harm for [[5-alpha-reductase inhibitor]] such as [[finasteride]] is not clear.<ref name="pmid18425978">{{cite journal |vauthors=Wilt TJ, MacDonald R, Hagerty K, Schellhammer P, Kramer BS |title=Five-alpha-reductase Inhibitors for prostate cancer prevention |veditors=Wilt TJ |journal=The Cochrane Database of Systematic Reviews |issue=2 |pages=CD007091 |date=April 2008 |pmid=18425978 |doi=10.1002/14651858.CD007091|pmc=11270836 }}</ref>

[[Vitamin]] supplementation does not appear to be effective at preventing cancer.<ref name="pmid20939459">{{cite journal |title=Vitamins and minerals: not for cancer or cardiovascular prevention |journal=Prescrire International |volume=19 |issue=108 |page=182 |date=August 2010 |pmid=20939459 |url=http://english.prescrire.org/en/81/168/46461/0/2010/ArchiveNewsDetails.aspx?page=2 |url-status=live |archive-url=https://web.archive.org/web/20120525134048/http://english.prescrire.org/en/81/168/46461/0/2010/ArchiveNewsDetails.aspx?page=2 |archive-date=25 May 2012}}</ref> While low blood levels of [[vitamin D]] are correlated with increased cancer risk,<ref name="pmid16595781">{{cite journal |vauthors=Giovannucci E, Liu Y, Rimm EB, Hollis BW, Fuchs CS, Stampfer MJ, Willett WC |title=Prospective study of predictors of vitamin D status and cancer incidence and mortality in men |journal=Journal of the National Cancer Institute |volume=98 |issue=7 |pages=451–59 |date=April 2006 |pmid=16595781 |doi=10.1093/jnci/djj101 |citeseerx=10.1.1.594.1654}}</ref><ref>{{cite web |title=Vitamin D Has Role in Colon Cancer Prevention |url=http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Vitamin_D_Has_Role_in_Colon_Cancer_Prevention.asp |access-date=27 July 2007 |archive-url=https://web.archive.org/web/20061204052746/http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Vitamin_D_Has_Role_in_Colon_Cancer_Prevention.asp |archive-date=4 December 2006 }}</ref><ref>{{cite journal |vauthors=Holick MF |title=Vitamin D, sunlight and cancer connection |journal=Anti-Cancer Agents in Medicinal Chemistry |volume=13 |issue=1 |pages=70–82 |date=January 2013 |pmid=23094923 |doi=10.2174/187152013804487308}}</ref> whether this relationship is causal and vitamin D supplementation is protective is not determined.<ref name="pmid16595770">{{cite journal |vauthors=Schwartz GG, Blot WJ |title=Vitamin D status and cancer incidence and mortality: something new under the sun |journal=Journal of the National Cancer Institute |volume=98 |issue=7 |pages=428–30 |date=April 2006 |pmid=16595770 |doi=10.1093/jnci/djj127|doi-access=free }}</ref><ref name=Futil2014>{{cite journal |vauthors=Bolland MJ, Grey A, Gamble GD, Reid IR |title=The effect of vitamin D supplementation on skeletal, vascular, or cancer outcomes: a trial sequential meta-analysis |journal=The Lancet. Diabetes & Endocrinology |volume=2 |issue=4 |pages=307–320 |date=April 2014 |pmid=24703049 |doi=10.1016/S2213-8587(13)70212-2}}</ref> One 2014 review found that supplements had no significant effect on cancer risk.<ref name=Futil2014/> Another 2014 review concluded that vitamin D<sub>3</sub> may decrease the risk of death from cancer (one fewer death in 150 people treated over 5 years), but concerns with the quality of the data were noted.<ref>{{cite journal |vauthors=Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud C |s2cid=205189615 |title=Vitamin D supplementation for prevention of mortality in adults |journal=The Cochrane Database of Systematic Reviews |volume=1 |issue=1 |pages=CD007470 |date=January 2014 |pmid=24414552 |doi=10.1002/14651858.cd007470.pub3|pmc=11285307 }}</ref>

[[Beta-Carotene]] supplementation increases lung cancer rates in those who are high risk.<ref name="pmid21738614">{{cite journal | vauthors = Fritz H, Kennedy D, Fergusson D, Fernandes R, Doucette S, Cooley K, Seely A, Sagar S, Wong R, Seely D | title = Vitamin A and retinoid derivatives for lung cancer: a systematic review and meta analysis | journal = PLOS ONE | volume = 6 | issue = 6 | pages = e21107 | year = 2011 | pmid = 21738614 | pmc = 3124481 | doi = 10.1371/journal.pone.0021107 | bibcode = 2011PLoSO...621107F | veditors = Minna JD | doi-access = free }}</ref> [[Folic acid]] supplementation is not effective in preventing colon cancer and may increase colon polyps.<ref name="pmid17551129">{{cite journal | vauthors = Cole BF, Baron JA, Sandler RS, Haile RW, Ahnen DJ, Bresalier RS, McKeown-Eyssen G, Summers RW, Rothstein RI, Burke CA, Snover DC, Church TR, Allen JI, Robertson DJ, Beck GJ, Bond JH, Byers T, Mandel JS, Mott LA, Pearson LH, Barry EL, Rees JR, Marcon N, Saibil F, Ueland PM, Greenberg ER | title = Folic acid for the prevention of colorectal adenomas: a randomized clinical trial | journal = JAMA | volume = 297 | issue = 21 | pages = 2351–2359 | date = June 2007 | pmid = 17551129 | doi = 10.1001/jama.297.21.2351 | doi-access = free }}</ref> Selenium supplementation has not been shown to reduce the risk of cancer.<ref>{{cite journal | vauthors = Vinceti M, Filippini T, Del Giovane C, Dennert G, Zwahlen M, Brinkman M, Zeegers MP, Horneber M, D'Amico R, Crespi CM | title = Selenium for preventing cancer | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD005195 | date = January 2018 | pmid = 29376219 | pmc = 6491296 | doi = 10.1002/14651858.CD005195.pub4 }}</ref>

=== Vaccination ===
[[Vaccine]]s have been developed that prevent infection by some [[carcinogen]]ic viruses.<ref name=vacc_facts_nci>{{cite web |url=https://www.cancer.gov/about-cancer/causes-prevention/vaccines-fact-sheet |title=Cancer Vaccine Fact Sheet |publisher=[[National Cancer Institute|NCI]] |date=8 June 2006 |access-date=28 March 2018 }}</ref> [[HPV vaccine|Human papillomavirus vaccine]] ([[Gardasil]] and [[Cervarix]]) decrease the risk of developing [[cervical cancer]].<ref name=vacc_facts_nci/> The [[hepatitis B vaccine]] prevents infection with hepatitis B virus and thus decreases the risk of liver cancer.<ref name=vacc_facts_nci/> The administration of human papillomavirus and hepatitis B vaccinations is recommended where resources allow.<ref name="pmid24176569">{{cite journal |author4-link=Ding-Shinn Chen |vauthors=Lertkhachonsuk AA, Yip CH, Khuhaprema T, Chen DS, Plummer M, Jee SH, Toi M, Wilailak S |title=Cancer prevention in Asia: resource-stratified guidelines from the Asian Oncology Summit 2013 |journal=The Lancet. Oncology |volume=14 |issue=12 |pages=e497–507 |date=November 2013 |pmid=24176569 |doi=10.1016/S1470-2045(13)70350-4|arxiv=cond-mat/0606434 }}</ref>