Cancer explained

1. CANCER EXPLAINED
What is cancer?
Cancer isa disease whichoccurswhenchangesinagroup of normal cellswithinthe bodyleadto
uncontrolledgrowthcausingalumpcalledatumour;thisis true of all cancers exceptleukaemia(cancer
of the blood).If leftuntreated,tumourscangrow and spreadintothe surroundingnormal tissue,orto
otherparts of the bodyviathe bloodstreamandlymphaticsystems,andcanaffectthe digestive,
nervousandcirculatorysystems.
Tumours (lumps) can be benignor malignant
Benigntumours are notcancerousand rarelythreatenlife.2Theytendtogrow quite slowly,donot
spreadto otherparts of the bodyandare usuallymade upof cellsquite similartonormal /healthy
cells.3Theywill onlycause aproblemif theygrow verylarge,becominguncomfortableorpressonother
organs - for example abraintumourinside the skull .
Malignant tumours are fastergrowingthanbenigntumoursandhave the abilitytospreadand
destroyneighbouringtissue.Cellsof malignanttumourscanbreakoff fromthe main (primary) tumour
and spreadto otherparts of the bodythrough a processknownas metastasis.Uponinvadinghealthy
tissue atthe newsite theycontinue todivideandgrow.These secondarysitesare knownasmetastases
and the conditionisreferredtoasmetastaticcancer.
Cancer can be classifiedaccordingto the followingcategories:
Carcinoma – A cancer that arisesfromthe epithelial cells(the lining of cellsthathelpsprotector
enclose organs).Carcinomasmayinvade the surroundingtissuesandorgansandmetastasise tothe
lymphnodesandotherareasof the body.The most commonformsof cancer inthisgroup are breast,
prostate,lungandcoloncancer •
Sarcoma – A type of malignanttumourof the bone or softtissue (fat,muscle,bloodvessels,nerves
and otherconnective tissuesthatsupportandsurroundorgans).The mostcommonformsof sarcoma
are leiomyosarcoma,liposarcomaandosteosarcoma•
Lymphoma – Lymphomaisa cancer of the lymphaticsystem, whichrunsall throughthe body,and
can therefore occuranywhere.The twomainformsare non-Hodgkin’swhichbeginswithuncontrolled
growthof the - white bloodcells -lymphocytes - of the immune system) andHodgkin’slymphomain
whichcellsof the lymphnodesbecome cancerous•
Leukaemia- Leukaemiaisacancer of the white bloodcellsandbone marrow,the tissue thatforms
bloodcells.There are several subtypes;commonare lymphocyticleukaemiaandchroniclymphocytic
leukaemia.

2. Causes
There are about200 knowntypesof cancer.As withmostillnessescancerismultifactorial,meaning
there isno single cause foranyone type of cancer.
A. Cancer-causingsubstances(carcinogens) - Genesare codedmessagesinsideacell thattell it
howto behave (i.e.whichproteinstomake).Mutationorchangestothe gene,suchas damage
or loss,can alterhowthat cell behaves.Forexample,amutationmaymeanthattoo much
proteinismade,or thatproteinisnot made at all.Significantly,thereneedstobe a numberof
geneticmutations3withinacell before itbecomescancerous.Somethingthatdamagesacell,
changingitsbehaviourandmakesitmore likelytobe cancerousiscalleda 'carcinogen'•
B. Age – Many typesof cancerbecome more prevalentwithage.The longerpeople live,the more
exposure there istocarcinogensandthe more time there isforgeneticchangesormutationsto
occur withintheircells•
C. Genetics– Some people are unfortunatelybornwithageneticallyinheritedhighriskfora
specificcancer('geneticpredisposition).Thisdoesnotmeandevelopingcancerisguaranteed,
but a geneticpredispositionmakesthe disease more likely.
o For example, womenthatcarry the BRCA 1 and BRCA 2 breastcancer geneshave a higher
predispositiontodevelopingthisformof cancerthan womenwitha normal breastcancer
risk.2However,lessthan5%of all breastcancer isknownto be due to genes.Soalthough
womenwithone of these genesare individuallymore likelytodevelopbreastcancer,most
casesare not causedbya highriskinheritedgenefault.Thisistrue of othercommon
cancers where some people have ageneticpredisposition - forexample,colon(large bowel)
cancer
D. The immune system- People whohave weakenedimmune systemsare more atriskof
developingsome typesof cancer.Thisincludespeople whohave hadorgantransplantsandtake
drugsto suppresstheirimmune systemstostoporganrejection,pluspeople whohave HIV or
AIDS, or othermedical conditionswhichreduce theirimmunitytodisease.
Certainlifestylesandenvironmental factorsare alsoknowntocause mutationsthatcan cause cancer.
Lifestyle andenvironmentalcausesare toa large extentcontrollableoravoidable.Examplesinclude:
1. Bodyweight,dietandphysical activity - Cancerexpertsestimatethatmaintainingahealthy
bodyweight,makingchangestoourdietandtakingregularphysical activitycouldpreventabout
one inthree deathsfromcancer. Many people eattoomuchred and processedmeatandnot
enoughfreshfruitandvegetables.Thistype of dietisknowntoincrease the riskof cancer.
2. Overweightor obesity- 'Obese'meansbeingmore thanabout25% overweight.Overweightor
obese people have anincreasedriskof bowel andpancreaticcancer,probablydue toa
tendencytowardshigherinsulinlevels.Obesitycanalsoincrease the riskof cancerof the
foodpipe (oesophagealcancer),kidneyandgallbladdercancer,aswell asbreastor womb
(uterine) cancerinwomen.
3. Alcohol - The evidence thatall typesof alcoholicdrinksare acause of a numberof cancersis
nowstrongerthan everbefore. Alcohol canincrease the riskof a numberof cancers,including

3. mouth,throat (whichincludespharyngeal cancer),laryngeal andcancerof the food pipe,plus
liver,breastandbowel cancer(inmen).Evenmoderate alcoholintake increasesthe riskof
cancer .
4. Tobacco – Tobacco smoke containsat least80 differentcancer-causingsubstances(carcinogenic
agents).Whensmoke isinhaledthe chemicalsenterthe lungs,passintothe bloodstreamand
are transportedthroughoutthe body.6Thisiswhysmokingorchewingtobacconot onlycauses
lungcancer and mouthcancers,but isalsorelatedtomany othercancers.The more a person
smokes,the youngertheystart,andthe longertheykeepsmoking,all furtherincreasethe risk
of cancer.
5. Ionisingradiation – Manmade sourcesof radiationcan cause cancer and are a riskfor workers.
The main riskishowever,prolongedandunprotectedexposure toultravioletradiationsfrom
the sun whichcan leadtomelanomaandskinmalignancies.7Fairskinnedpeople,those withlot
of molesorwhohave a relative whohashad melanomaornonmelanomaskincancer,are at
highestrisk.
6. Work place hazards - Some people riskbeingexposedtoacancer causingsubstance because of
the work thattheydo. For example,workersinthe chemical dye industryhave beenfoundto
have a higherincidence thannormal of bladdercancer.Asbestosisawellknownworkplace
cause of cancer - particularlyacancer calledmesothelioma,3whichmostcommonlyaffectsthe
coveringof the lungs(pleura) .
7. Infection– A proportionof cancerscan be causedby infectionwithavirus.However,thisdoes
not meanthat these cancerscan be caught like aninfection;ratherthe viruscancause changes3
incellsthat make themmore likelytobecome cancerous
o Examplesincludecervical cancer,linkedtothe HumanPapillomaVirus,primaryliver
cancer whichcan be causedby the HepatitisBand C virusand lymphomaslinkedtothe
Epstein-Barrvirus8.
o Bacterial infectionshave notbeenthoughtof ascancer causingagentsinthe past. But
studieshave shownthatpeople whohave helicobacterpylori infectionof theirstomach
developinflammationof the stomachlining,whichincreasesthe riskof stomachcancer.
 Signsand symptomsAsthere are so manydifferenttypesof cancerthe symptomsare varied
and dependonwhere the diseaseislocated.However,thereare some keysignsandsymptoms9
, including:
 Lumps – some cancerscan be feltthroughthe skin.Cancerouslumpsare oftenpainlessandmay
increase insize asthe cancer progresses.
 Coughing, breathlessness–persistentcoughingepisodesandbreathlessnesscanbe associated
withlungcancer.
 Changesin bowel habit – symptomsof bowel cancermayinclude bloodinthe stoolsanda
change in bowel habitssuchasconstipationanddiarrhea.
 Bleeding–anyunexpectedbleedingcanbe a signof cancer:
 Bleedingfromthe anal passage maybe a signof bowel cancero
 Bleedingfromthe cervix maybe asignof cervical cancero Bloodpresentinthe urine
may be a signof kidneyorbladdercancer•

4.  Unexplainedweightloss– a large amountof unexplainedweightlossoverashortperiodof
time (acouple of months) can be a signof cancer •
 Fatigue - fatigue isextreme tirednessandasevere lackof energy.If fatigue isdue tocancer,
sufferers normallyalsohave othersymptoms.
The global cancer epidemicThe incidenceandburdenof canceris huge andis setto rise.Cancerkills
more people ona global scale thanAIDS,malariaand TB combined.Manyof the 600,000 deathseach
monthattributedto cancer can be preventedwithincreasedgovernmental supportandfundingfor
prevention,detectionandtreatmentprogrammes.
The incidence of canceris highestindevelopedcountries,particularlyinNorthernAmerica,Australia
and NewZealandandinNorthernandWesternEurope.However,the impactinthe developingworldis
growingat an alarmingrate.More than 70% of all cancer deathsalreadyoccurin low- andmiddle-
income countriesandthese regionsare projectedtoaccountfor twothirds of all cases of cancer
worldwide by2050 (an increase of 15% since 1975).
There are significantregional differencesincancerprevalence,butthe biggestcancerkillersworldwide
are lungcancer (1.4 milliondeathsin2008),stomach cancer (740,000 deathsin2008), livercancer
(700,000 deathsin2008), colorectal cancer (610,000 deathsin2008), and breastcancer (460,000 deaths
in2008).
In additiontothe impacton lossof life,the economicimpactof canceris huge.Currentlyitisestimated
that the disease costseconomiesacrossthe worldanestimated$290 billionin2010 - $154 billionof
whichwere medical costs.
The future cancer burden:
The global cancer epidemicissettocontinue rising,placingfurtherstrainsonbothindividualsandthe
families,andthe societiesinwhichtheylive.The numberof cancercasesand relateddeathsworldwide
isestimatedtodouble overthe next20-40 years.Withthe greatestincrease inlow- andmiddle-income
countries;those leastequippedtocope withboththe social and economicimpactof the disease
Worryingly,it isexpectedthat by 2030:
 There will be 12 millioncancerdeathsperyear•
 The global costs of cancer are estimatedtorise to458 billion.
The risingburdenof canceracross the worldcan be linkedtoa numberof factorsincluding:
 Expandingandageingpopulations.
 Increasesinmodifiable riskfactors(smoking,western dietandphysical inactivity) .
 Higherincidencesof cancersrelatedto preventableortreatable infections(particularlyin
developingcountries)

5. Preventionand earlydetectionof cancer
More than a thirdof all cancers are preventable byreducingexposure toriskfactorsincludingtobacco,
obesity,physicalinactivityand sexuallytransmittedinfections.11Preventative measuressuchas
vaccinationprogrammesagainstHBV andHPV andpubliceducationcampaignsare vital now,andinthe
future,tomitigate the expectedincreaseof peopleaffectedbycancerinthe comingdecades.
Early detectioncanalsoplayitspart inreducingthe global cancerepidemic.Implementationof
screeningprogrammestoidentifypre-cancerorearlystage cancerare crucial in the fightagainstthe
disease inbothdevelopedanddevelopingcountries. Inorderforearlydetectionprogrammestobe
effective,stronghealthcare systemsmustbe inplace to provide equityof accesstodiagnosisand
treatmentforall cancer patients.Inaddition,publiceducationcampaignsare neededacrossthe world
to tackle the cancer epidemicbyhelpingpeoplerecognise the earlysignsof disease andencourage the
seekingof promptmedical attention.
Call to action : Unlessurgentactionistakento raise awarenessaboutcancerand encourage
governmentstodeveloppractical,multisectoral strategiestoaddressthe disease,millionsof people
aroundthe worldwill continuetodie prematurelyorsuffereveryyearbecauseof thisdevastating
disease.
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2013
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http://www.wcrfuk.org/cancer_prevention/recommendations/alcohol_and_cancer.php?gclid=C
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5. Cancer ResearchUK.Available from:
http://info.cancerresearchuk.org/healthyliving/smokingandtobacco/.
6. Last accessedJanuary 2013 7 AmericanCancerSociety.
http://www.cancer.org/Cancer/CancerCauses/OtherCarcinogens/MedicalTreatments/radiation-
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PreparedBy Amjad Khan Afridi