CANCER for clinical students

1. Cancer andits Management
The differentcausesof cancerandits management
Age,gender,genetics,andlifestyle asriskfactorsdependonthe type
Cancer isthe secondmostcommoncause of deathafterheart disease inmostWesterncountries.In
some countries,itisthe leadingcause of death.Althoughabout1in 3 people inWesterncountries
developscanceratsome stage inlife,manypeople canbe curedbecause of advancesindiagnosisand
treatment.
Many typesof cancer produce a solidtumourthat formsinan organ, such as the breast,intestine,or
bladder.If notdetectedandtreated,these cancersmayspreadtootherbody tissues.Othercancersare
oftenwidespreadfromearlyon,suchas cancerof the lymphnodes(see Lymphoma) andcancerof
blood-formingcellsinthe bone marrow(see Leukaemia).
What are the causes?
Cancer occurs whencellsdivide andgrow inan uncontrolledmanner.Celldivisionandcell functioning
are controlledbygenes,anddefectsinsome of these genescanleadtoa cell becomingcancerous.In
bothchildrenandadults,these defects(mutations) inthe genesmaybe causedbyenvironmental
factors suchas chemicals(especiallyfromsmoking),viruses,ultravioletlight,orothertypesof radiation.
In some cases,an abnormal gene isinheritedfromaparent.The maincausesof cancer varyin different
age groups.
Childrenandadultswithreducedimmunity,suchasthose withAIDS(see HIV infectionandAIDS) or
people whoare takingimmunosuppressants,have anincreasedriskof developingcertaintypesof
cancer. Insuch people,agentssuchasvirusesare more likelytocause cancer.
Childhoodcancers
The varioustypesof leukaemia(cancerof the bone marrow) are byfar the mostcommoncancers
affectingchildren.

2. Cancer inchildren
Cancersin childrenare rare,affectingabout1 in500 childrenunderthe age of 15 inthe UK, but theyare
still amajor cause of deathininfancy.The mostcommonchildhoodcancersare leukaemiaandtumours
of the brainand spinal cord(see Brainand spinal cordtumoursinchildren).
The cause of most typesof cancer inchildrenisnotknown.Some cancers,suchas a neuroblastoma,
occur primarilyinchildren.A neuroblastomadevelopsinanadrenal glandorthe nervoussystemfrom
tissue thatnormallydisappearsduringfetal development.Cancersof thistype are mostcommonduring
infancy.Othertypesof childhoodcancer,suchasprimarybone cancer, affectolderchildren.
Occasionally,cancerisdue toan inheritedabnormal gene orgenes.About half of all casesof the eye
cancer retinoblastomaare mainlygeneticinorigin,andkidneycancer(see Wilms’tumour)sometimes
runs infamilies.Insuchcases,one or more familymembersmayhave the same cancer.
The risk of cancer is increasedinsome geneticdisorders.Forexample,childrenwithDown’ssyndrome
are 10–20 timesmore likelythanotherchildrentodevelopleukaemia.
Some cancersin childrenmaybe causedbyenvironmentalfactors.Forexample,certainviruses,suchas
the Epstein–Barrvirus,are knownto cause some typesof cancer, includingone type of childhood
lymphoma.
Cancer inadults
Cancer occurs muchmore commonlyinadultsthanin children.Inthe UK,about 1 in 3 people develops
cancer at some time inadultlife.The mostcommon typesof cancer that occur inadultsare lungcancer,
skincancer,breastcancer, colorectal cancer,and prostate cancer.
Many cancers inadultsunderthe age of 40 have a significantinheritedfactor.Upto 1 in 10 casesof
cancer of the ovary,breastcancer,prostate cancer, and colorectal cancerare due inpart to inheritance
of abnormal genes.Inolderpeople,acombinationof several factorseventuallyleadstocancer.The
mostcommon factorsare carcinogens(cancer-causingagents),whichincludecertainchemicals

3. (particularlythose foundintobaccosmoke),dietaryfactors,some viruses,andspecifictypesof
radiation,includingthe ultravioletlightinnatural sunlight.
In adultsoverthe age of 50, the total numberof newlydiagnosedcancercases roughlydoubleseach
decade.Therefore,an80-year-oldpersoniseighttimesmore likelytohave cancerthana 50-year-old
person.Some cancers,suchas certaintypesof skincancer and prostate cancer,are verycommoninold
age,but these cancersmayoftenbe presentwithoutcausingseriousproblems.
What are the symptoms?
Sometimes,acancerisdetectedbefore itcausessymptoms,oftenduringaroutine screeningtest.
However,cancerismore oftendiscoveredwhensymptomsgraduallydevelopandbecome noticeable
overa periodof weeksormonths,promptingapersonto visita doctor.The symptomsof cancermay
include:
A lump,whichisoftenfirmandpainless,inorbeneaththe skin.
Changesinthe appearance of a mole.
A nonhealingwound.
Bloodinthe urine or sputum.
Changesinbowel habits.
A discharge containingbloodfromthe rectumorvagina.
Persistentabdominal pain.

4. Persistentcough.
Hoarsenessorchangesinthe voice.
Difficultywithswallowing.
Severe,recurrentheadaches.
Many cancers alsoproduce more general symptoms,whichmayinclude:
Weightloss.
Unexplainedtiredness.
Loss of appetite andnausea.
If you experience one ormore of these symptoms,youshouldconsultyourdoctoras soonas possible.
How isit diagnosed?
Routine screeningisconstantlyimprovingthe earlydiagnosisof cancer.Screeningaimstodetectdisease
before symptomsare present.Anexampleisexaminationof the large intestine,suchasa colonoscopy
or a rectal examination,tolookforcolorectal cancer.Otherscreeningteststhatare commonlyused
include mammographytocheckforbreastcancer and the cervical smeartestto lookforprecancerous
cellsthatmay leadto cancerof the cervix.

5. Alternatively,cancermaybe diagnosedasa resultof tests to investigatesymptoms.Suchtestsmay
include imagingtests,suchasX-rays,ultrasoundscanning,CTscanning,orMRI. In a few cases,blood
testsmay be performed.Forexample,one testlooksforproteinsthatindicate aparticulartype of
tumour.To confirma diagnosis,itisusuallynecessarytohave a biopsy,inwhichasample of abnormal
tissue isremovedandtestedtofindoutif cancer ispresent.If canceris present,furthertestswill
identifythe type of cell inthe tissue thathasbecome cancerous,whichcangive anindicationof how
fastthe tumourislikelytogrowand the bestwayto treat it.Once a diagnosisof cancerhas beenmade,
youwill probablyhave teststoinvestigate how farthe cancerhas spreadfromits original site (see
Stagingcancer).
What are the treatments?
Althoughcancercan developatmanydifferentsitesaroundthe body,the generalprinciplesof
treatmentare the same.The chancesof a cancer beingcurable are highestif itisdetectedbyscreening
at a sufficiently earlystage before itcausessymptoms.
The three maintechniquesusedtotreatcancerare surgery,chemotherapy,andradiotherapy.Other
treatmentsinclude biological andhormonal therapies.
Dependingonthe type andthe stage of cancer,treatmentmaybe intendedtocure the cancer,slowthe
growthof the cancer, or be palliative(inwhichtreatmentisintendedtohelpapersonlive as
comfortablyaspossible ratherthanattempttocure the cancer).
In mostcases,curative treatmentinvolvesthe surgical removal of atumour.In additiontosurgery,
nonsurgical treatments,suchaschemotherapyandradiotherapy,are oftengivenwiththe aimof
destroyinganycancercellsthathave spreadbeyondthe obvioussolidtumour.Nonsurgical treatments
may alsobe usedif a cure is notpossible withthe aimof slowingthe growthof certaintypesof cancer
rather thancuring them.Palliativecare can control the symptomsof cancer,maximize qualityof life,
and provide psychological helpforyouandyourfamilyasyou come to termswiththe processof dying.
Palliativecare mayalsoprolonglife,althoughthatisnotitsprimaryaim.
Treatmentistailoredtothe type and the extentof the cancer,your age,yourgeneral health,andyour
wishesafterdiscussingthe outlookandoptionswithdoctorsandfamily.Forexample,attemptstocure
a cancer may not be appropriate inextreme oldage because of the adverse effectsof the treatment.
Instead,treatmentmaybe offeredtorelievesymptomsandtoimprove qualityof life forthe time left.

6. Surgery
Surgical removal of a tumouris the maintreatmentformostcommonsolidtumoursat an earlystage.
Duringsurgery,itis usual to remove some normal tissue surroundingthe tumourtomaximize the
chancesthat all cancerouscells are removedfromthe body.Sometimes,the lymphnodesnearthe
tumourare alsoremovedbecause canceroftenspreadstothese nodesfirst.Lesscommonly,surgery
aimsto remove tumoursthathave spreadto more distantsitesinthe body.
Surgerymay notbe appropriate if atumouris inaccessible.Forexample,surgerytoremove atumour
deepinside the brainmaycause greatdamage to healthybraintissue.Surgerymayalsonotbe the best
treatmentif the cancer hasalreadyspreadto otherparts of the body.In such cases,othertreatments,
includingchemotherapyorradiotherapy,maybe appropriate.
Surgerymay be usedas a palliativetreatmentforcertaintypesof cancer(see Palliative surgeryfor
cancer).For example,surgerymaybe carriedoutto remove a tumourthat isblockingthe bowel orbile
duct or to treat fracturesof bonesthathave beenweakenedbycancer.
Treatmentwithanticancerdrugs
In chemotherapy,anticancerdrugsare usedto kill cancerouscells.Thisisthe principal treatmentfor
leukaemiasandothercancersthat are widespreadinthe body.Itmay alsobe usedfor solidtumours
that have spreadto otherparts of the body or to reduce the riskof furtherspread.Like surgery,
chemotherapymaybe usedtocure cancer or as a palliative treatment.The side effectsvarywiththe
type of drug, butcan include nauseaandvomiting,temporaryhairloss(see Alopecia),constipation,
diarrhoea,tiredness,andrarelykidneydamage oranaemia.Youmaybe offeredtreatmentsforsome of
these side effects,suchasantiemeticdrugsfornauseaandvomitingorbloodtransfusionsforanaemia.
The durationof treatmentvariesdependingonthe type of cancerand the aim of the treatment.
Treatmentwithradiation
In thistechnique,radiationisdirectedatcancerouscellsandtissue todestroythemorslow theirgrowth
(see Radiotherapy).Itmaybe usedcurativelyorpalliatively.Alsoknownasradiationtherapy,
radiotherapycanhave seriousside effects,althoughfewerside effectsare likelytooccurwithmodern
techniquesbecauseradiationcanbe targetedatthe cancerousarea more effectively,therebyreducing
the amountnormal tissuesreceive.

7. Fatigue isa commongeneral effectof radiotherapy.Otherside effectsthatmayoccur vary depending
on the site beingtreated,andanyareathat receivesahighdose of radiationwill be affected.For
example,radiotherapytothe breastor headoftencausesrednessorsorenessof the skin;treatmentto
the scalp usuallycauseshairloss;andradiotherapytothe abdomenorpelvistypicallycausesnausea,
abdominal cramps,anddiarrhoea.Manyside effectscanbe relievedwithdrugsandclearup afterthe
course of radiotherapyhasbeencompleted.Radiotherapydoesnotmake the patientradioactive.
Hormonal therapies
Certaintypesof hormone affectthe cell growthandreplicationof some cancers.Forexample,the
female sex hormone oestrogenisknowntostimulate the growthof mostbreastcancersand also
suppressthe growthof prostate cancer.Treatmentwithsex hormonesplaysanimportantpartinthe
managementof these typesof cancer(see Sex hormonesandrelateddrugs).
Biological therapies
These newertypesof treatmentare beingusedincreasinglytotreatcancer.Unlike traditional cytotoxic
drugs,whichattack the cancer cells’DNA or RNA (geneticmaterial),biological therapiesare drugsthat
disruptspecificbiological processesof cancercellsorstimulate the immune systemagainstthe cancer
(see Anticancerdrugs).
Biological therapiesthatdisruptcancercells’biological processesworkinvariousways,dependingon
the specificprocesstheyaffect.Forexample,anti-angiogenesisagents(suchasbevacizumab,usedto
treat some casesof breastcancer) inhibitthe tumours’formationof new bloodvessels,which are
necessarytokeepthe tumoursalive.Sunitinib,usedtotreatsome kidneycancers,inhibitsaspecific
enzyme (calledtyrosinekinase) thatisessential fortumourgrowth.Erlotinib,usedtotreatsome cases
of lungcancer,and cetuximab,usedtotreatsome bowel cancers,blockparticulartypesof receptor
(calledepidermal growthfactorreceptors) andsopreventcancercellswiththesereceptorsfrom
growing.
Biological therapiesthatstimulatethe immunesystemmayinvolvetakingdrugsknownas“cancer
vaccines”.Forexample,substancessuchasinterferons,whichtriggersome typesof whitebloodcellto
attack abnormal cells,maybe manufacturedsyntheticallyandgivenasinterferondrugs.Youmayalso
be givensyntheticallycreatedanti-bodies(proteinsthatrecognize andattackforeigncellsorparticlesin
the body) that deliveraradioactive substance oranticancerdrugdirectlytoa cancer.

8. Althoughbiological therapiesare beingusedtosuccessfullytreatanincreasingrange of cancers,they
are notsuitable ineverycase.Like all drugtreatments,theymayalsocause side effects,suchasfever,
muscle aches,vomiting,fatigue,rash,anddiarrhoea.
Supportive care
A diagnosisof cancerand itstreatmentcanbe stressful andfrightening.The aimof supportive care isto
make life continue asnormallyaspossible.Youwill be offeredrelief forthe symptomsof cancer,suchas
pain(see Painreliefforcancer).Side effectsdue tocancertreatments,suchas vomiting,will alsobe
treated.Youand your familywillprobablybe offeredpsychologicalsupportandadvice fromthe medical
teaminvolvedinyourtreatment.Thesespecialistswill helpyoutounderstandandcope withthe
diagnosisandtreatmentof the cancer.You may wishtosee a counsellortoobtainadvice and
psychological support(see Counselling).Suchsupportcanboostyour emotional wellbeingandself-
esteem,whichmaybe particularlyaffectedif treatmenthascausedobviousphysical changes,suchas
removal of a breastor hair loss. Researchappearstoshow that people withapositive mental attitude
survive longerthanthose whosimplyresignthemselvestothe disease.
Sharingproblemswithpeople whohave hadsimilarpersonal experiencescanbe reassuring,anditmay
be possible to joinasupportgroup forpeople withcancerandtheirfamilies.
What isthe prognosis?
The earliera cancer isdiagnosed,the more likelyitisthattreatmentwill be successful andthe cancer
can be cured.The prognosisisusuallyexpressedintermsof a5-year survival rate (the percentage of
people alive5yearsafter the diagnosisof cancerismade).Formost typesof cancers,the outlookhas
beengreatlyimprovedduringthe lastfew decades,especiallyinchildren.Evenincaseswhere the
cancer cannot be cured,there isstill agood chance of long-termsurvivalwithafairlygoodqualityof life,
oftenformany yearsafterthe diagnosis.