cancer opt

8/3/2019 Cancer Opt

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OncologyOncology

Prepared by:Prepared by:

Jeremy M.Jeremy M. PantigPantig, R.N., N.C. II, M.N., R.N., N.C. II, M.N.

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Healthy CellsHealthy Cells Cells represent the smallest,Cells represent the smallest,

functional unit of our existencefunctional unit of our existencewhich contains cytoplasm andwhich contains cytoplasm anda nucleus (i.e. metabolism,a nucleus (i.e. metabolism,reproduction, day to dayreproduction, day to day

functions)functions) Cells have a specializedCells have a specialized

function depending on theirfunction depending on theirlocation in the body.location in the body.

Cells grow, replicate and repairCells grow, replicate and repairbody organs.body organs.

The genetic materialThe genetic material(DNA/RNA) and your immune(DNA/RNA) and your immunesystem regulate this process.system regulate this process.

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Things you need to understandThings you need to understand

SurfaceSurface--toto--volume ratio of cellsvolume ratio of cells

Chemical signals such as growth factorsChemical signals such as growth factorsand hormonesand hormones

Contact inhibitionContact inhibition

CyclinsCyclins andand cyclincyclin--dependent dependent kinaseskinases((CdksCdks) complexes) complexes

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SurfaceSurface--toto--volume ratio of cellsvolume ratio of cells\\

The ratio of surface to volume of the cell is very important. A cellThe ratio of surface to volume of the cell is very important. A cellget its food and gets rid of wastes through its surface.get its food and gets rid of wastes through its surface.

As a cell increases in size its surface to volume ratio decreases. As a cell increases in size its surface to volume ratio decreases.In other words the cell will reach a point where its surface isn't In other words the cell will reach a point where its surface isn't big enough to feed the volume of the cell or get rid of its wastesbig enough to feed the volume of the cell or get rid of its wastesfast enough. (Sort of like having an elephant with very smallfast enough. (Sort of like having an elephant with very smallopenings on either end.)openings on either end.)

The amount of DNAThe amount of DNA and RNA available in a cell can also limit aand RNA available in a cell can also limit acell's growth. If a cell tries to grow too large there will simply not cell's growth. If a cell tries to grow too large there will simply not be enough time for the DNA to produce enough RNA to code forbe enough time for the DNA to produce enough RNA to code forall the proteins that would need to be made for the cell. (Sort of all the proteins that would need to be made for the cell. (Sort of like having a kitchen for the Army but only one book of recipeslike having a kitchen for the Army but only one book of recipesto cook from.)to cook from.)

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Chemical signals such as growthChemical signals such as growthfactors and hormonesfactors and hormones

MitogensMitogens,, which stimulate cell division, primarily bywhich stimulate cell division, primarily byrelieving intracellular negative controls that otherwiserelieving intracellular negative controls that otherwise

block progress through the cell cycle.block progress through the cell cycle. 2.2.Growth factors,Growth factors, which stimulate cell growth (anwhich stimulate cell growth (an

increase in cell mass) by promoting the synthesis of increase in cell mass) by promoting the synthesis of proteins and other macromolecules and by inhibitingproteins and other macromolecules and by inhibitingtheir degradation.their degradation.

3.3.Survival factors,Survival factors, which promote cell survival bywhich promote cell survival bysuppressing apoptosis.suppressing apoptosis.

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Contact inhibitionContact inhibition

Cell property where they tend to growCell property where they tend to growonly until they meet other cells.only until they meet other cells.

Contact inhibition:Contact inhibition: cessation of cessation of replication of dividing cells that come intoreplication of dividing cells that come intocontact, as in the center of a healingcontact, as in the center of a healing

wound.wound.

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CyclinsCyclins andand cyclincyclin--dependent dependent kinaseskinases ((CdksCdks) complexes) complexes

are a family of proteinare a family of protein kinaseskinases first first discovered for their role in regulating thediscovered for their role in regulating thecell cycle. They are also involved incell cycle. They are also involved inregulating transcription, mRNA processing,regulating transcription, mRNA processing,and the differentiation of nerve cells.and the differentiation of nerve cells.

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Define CancerDefine Cancer

Cancer is a term used to describe a largeCancer is a term used to describe a largegroup of diseases that are characterizedgroup of diseases that are characterized

by a cellular malfunction. Healthy cellsby a cellular malfunction. Healthy cellsare programmed to know what to do andare programmed to know what to do andwhen to do it. Cancerous cells do not when to do it. Cancerous cells do not have this programming and thereforehave this programming and therefore

grow and replicate out of control. Theygrow and replicate out of control. Theyalso serve no physiological function.also serve no physiological function.These cells are now termed a neoplasm.These cells are now termed a neoplasm.

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CancerCancer Cancer is one of the most common diseases inCancer is one of the most common diseases in

the developed world:the developed world:

1 in 4 deaths are due to cancer1 in 4 deaths are due to cancer

1 in 17 deaths are due to1 in 17 deaths are due to lung cancerlung cancer

Lung cancer is the most common cancer in menLung cancer is the most common cancer in men

Breast cancer is the most common cancer inBreast cancer is the most common cancer inwomenwomen

There are over 100 different forms of cancerThere are over 100 different forms of cancer

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CancerCancer

The division of normal cells is preciselyThe division of normal cells is preciselycontrolled. New cells are only formed for growthcontrolled. New cells are only formed for growth

or to replace dead ones.or to replace dead ones. Cancerous cells divide repeatedly out of controlCancerous cells divide repeatedly out of control

even though they are not needed, they crowdeven though they are not needed, they crowdout other normal cells and function abnormally.out other normal cells and function abnormally.

They can also destroy the correct functioning of They can also destroy the correct functioning of major organs.major organs.

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What causes cancer?What causes cancer? Cancer arises from theCancer arises from the mutationmutation of a normalof a normal

gene.gene. Mutated genes that cause cancer are calledMutated genes that cause cancer are called

oncogenesoncogenes..

It is thought that several mutations need toIt is thought that several mutations need tooccur to give rise to canceroccur to give rise to cancer

Cells that are old or not functioning properlyCells that are old or not functioning properlynormally self destruct and are replaced bynormally self destruct and are replaced by

new cells.new cells. However, cancerous cells do not self destruct However, cancerous cells do not self destruct

and continue to divide rapidly producingand continue to divide rapidly producingmillions of new cancerous cells.millions of new cancerous cells.

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A factor which brings about a mutation is A factor which brings about a mutation is

called acalled a mutagen.mutagen.

A mutagen is A mutagen is mutagenic.mutagenic.

Any agent that causes cancer is called a Any agent that causes cancer is called acarcinogencarcinogen and is described asand is described as

carcinogeniccarcinogenic..

So some mutagens are carcinogenic.So some mutagens are carcinogenic.

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CarcinogensCarcinogens Ionising radiationIonising radiation X Rays, UV light X Rays, UV light

ChemicalsChemicals tar from cigarettestar from cigarettes

Virus infection Virus infection papilloma virus can bepapilloma virus can beresponsible for cervical cancer.responsible for cervical cancer.

Hereditary predispositionHereditary predisposition Some families areSome families aremore susceptiblemore susceptible to getting certain cancers.to getting certain cancers.RememberRemember you cant inherit canceryou cant inherit cancer its just that its just that you maybe more susceptible to getting it.you maybe more susceptible to getting it.

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Benign or malignant?Benign or malignant?

Benign tumoursBenign tumours do not spread from their site of origin,do not spread from their site of origin,but can crowd out (squash) surrounding cells eg brainbut can crowd out (squash) surrounding cells eg braintumour, warts.tumour, warts.

Malignant tumoursMalignant tumours can spread from the original sitecan spread from the original siteand causeand cause secondary tumourssecondary tumours. This is called. This is calledmetastasismetastasis. They interfere with neighbouring cells and. They interfere with neighbouring cells andcan block blood vessels, the gut, glands, lungs etc.can block blood vessels, the gut, glands, lungs etc.

Why are secondary tumours so bad?Why are secondary tumours so bad?

Both types of tumour can tire the body out as theyBoth types of tumour can tire the body out as theyboth need a huge amount of nutrients to sustain theboth need a huge amount of nutrients to sustain the

rapid growth and division of the cells.rapid growth and division of the cells.

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TumorsTumors Benign TumorsBenign Tumors

(noncancerous)(noncancerous)

Enclosed in a fibrousEnclosed in a fibrous

shell or capsule.shell or capsule. Take up spaceTake up space

Concerned if theyConcerned if theyinterfere withinterfere withsurrounding tissues orsurrounding tissues orvessels or impede thevessels or impede thefunction of the body.function of the body.

Malignant TumorsMalignant Tumors(cancerous)(cancerous)

Not usually containedNot usually contained

metastasismetastasis Invade and emit Invade and emit

clawlike protrusionsclawlike protrusionsthat disrupt the RNAthat disrupt the RNA

and DNA of normaland DNA of normalcells (these cancerouscells (these cancerouscells act like a virus).cells act like a virus).

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The Development of CancerThe Development of Cancer

Within every nucleus of every one of theWithin every nucleus of every one of thehuman body's 30 trillion cells exists DNA,human body's 30 trillion cells exists DNA,

the substance that contains thethe substance that contains theinformation needed to make and controlinformation needed to make and controlevery cell within the body. Here is a closeevery cell within the body. Here is a close--

up view of a tiny fragment of DNA.up view of a tiny fragment of DNA.

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1. DNA of a normal cell1. DNA of a normal cell

This piece of DNA is an exact copy of the DNA fromThis piece of DNA is an exact copy of the DNA from

which it came.W

hen the parent cell divided to createwhich it came.W

hen the parent cell divided to createtwo cells, the cell's DNA also divided, creating twotwo cells, the cell's DNA also divided, creating twoidentical copies of the original DNA.identical copies of the original DNA.

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2. Mutation of DNA2. Mutation of DNA

Here is the same section of DNA but from another cell. If youHere is the same section of DNA but from another cell. If youcan imagine that DNA is a twisted ladder, then each rung of thecan imagine that DNA is a twisted ladder, then each rung of theladder is a pair of joined molecules, or a base pair. With thisladder is a pair of joined molecules, or a base pair. With thissection of DNA, one of the base pairs is different from thesection of DNA, one of the base pairs is different from the

original.original.

This DNA has suffered aThis DNA has suffered a mutationmutation, either through mis, either through mis--copyingcopying(when its parent cell divided), or through the damaging effects(when its parent cell divided), or through the damaging effectsof exposure toof exposure to radiation or a chemical carcinogen.radiation or a chemical carcinogen.

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3. Genetically altered cell3. Genetically altered cell

Body cells replicate through mitosis, they respond toBody cells replicate through mitosis, they respond totheir surrounding cells and replicate only to replacetheir surrounding cells and replicate only to replaceother cells. Sometimes aother cells. Sometimes a genetic mutationgenetic mutation will cause awill cause acell and its descendants to reproduce even thoughcell and its descendants to reproduce even thoughreplacement cells are not needed.replacement cells are not needed.

The DNA of the cell highlighted above has aThe DNA of the cell highlighted above has a mutationmutationthat causes the cell to replicate even though thisthat causes the cell to replicate even though thistissue doesn't need replacement cells at this time or at tissue doesn't need replacement cells at this time or at this place.this place.

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4. Spread and second mutation4. Spread and second mutation

The genetically altered cells have, over time,The genetically altered cells have, over time, reproducedreproduceduncheckedunchecked, crowding out the surrounding normal cells. The, crowding out the surrounding normal cells. Thegrowth may contain one million cells and be the size of agrowth may contain one million cells and be the size of apinhead. At this point the cells continue to look the same as thepinhead. At this point the cells continue to look the same as the

surrounding healthy cells.surrounding healthy cells.

After about a million divisions, there's a good chance that one After about a million divisions, there's a good chance that oneof the new cells will haveof the new cells will have mutated furthermutated further. This cell, now. This cell, nowcarrying twocarrying two mutant genesmutant genes, could have an, could have an altered appearancealtered appearanceand be even more prone to reproduce unchecked.and be even more prone to reproduce unchecked.

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5. Third mutation5. Third mutation

Not all mutations that lead to cancerous cells result in the cellsNot all mutations that lead to cancerous cells result in the cellsreproducing at a faster, more uncontrolled rate. For example, areproducing at a faster, more uncontrolled rate. For example, amutation may simply cause a cell to keep from self mutation may simply cause a cell to keep from self--destructing.destructing. All normal cells have surveillance mechanisms that look for All normal cells have surveillance mechanisms that look fordamage or for problems with their own control systems. If suchdamage or for problems with their own control systems. If such

problems are found, the cell destroys itself.problems are found, the cell destroys itself.Over time and after many cell divisions, aOver time and after many cell divisions, a third mutationthird mutation maymayarise. If the mutation gives the cell some further advantage,arise. If the mutation gives the cell some further advantage,that cell will grow more vigorously than its predecessors andthat cell will grow more vigorously than its predecessors andthus speed up thethus speed up the growth of the tumourgrowth of the tumour..

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6. Fourth mutation6. Fourth mutation

The new type of cells grow rapidly, allowing forThe new type of cells grow rapidly, allowing formore opportunities for mutations. The next more opportunities for mutations. The next mutation paves the way for the development of mutation paves the way for the development of

an even morean even more aggressive canceraggressive cancer..

At this point the tumour is still contained At this point the tumour is still contained..

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7. Breaking through the membrane7. Breaking through the membrane

The newer, wilder cells created by another mutation areThe newer, wilder cells created by another mutation areable toable to push their way through the epithelial tissue'spush their way through the epithelial tissue'sbasement membranebasement membrane, which is a meshwork of protein, which is a meshwork of proteinthat normally creates a barrier. The invasive cells in thisthat normally creates a barrier. The invasive cells in thistumour aretumour are no longer containedno longer contained..

At this point the cancer is still At this point the cancer is still too small to be detectedtoo small to be detected..

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8. Angiogenesis8. Angiogenesis

Often during the development of earlier stages of the tumour,Often during the development of earlier stages of the tumour,or perhaps by the time the tumour has broken through theor perhaps by the time the tumour has broken through thebasement membrane (as pictured above),basement membrane (as pictured above), angiogenesisangiogenesis takestakesplace.place. Angiogenesis is the recruitment of blood vessels from Angiogenesis is the recruitment of blood vessels fromthe network of neighbouring vessels.the network of neighbouring vessels.

Without blood and the nutrients it carries, a tumour would beWithout blood and the nutrients it carries, a tumour would beunable to continue growing. With the new blood supply,unable to continue growing. With the new blood supply,however, thehowever, the growth of the tumour acceleratesgrowth of the tumour accelerates; it soon; it sooncontainscontains thousand million cellsthousand million cells and, now the size of a smalland, now the size of a smallgrape, is large enough to be detected as a lumpgrape, is large enough to be detected as a lump

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9.Invasion and dispersal9.Invasion and dispersal

The tumour has nowThe tumour has now invaded the tissueinvaded the tissue beyond thebeyond thebasement membrane.basement membrane.

Individual cells from the tumour enter into the networkIndividual cells from the tumour enter into the networkof newly formed blood vesselsof newly formed blood vessels, using these vessels as, using these vessels ashighways by which they can move to other parts of thehighways by which they can move to other parts of thebody. A tumour as small as a gram can send out abody. A tumour as small as a gram can send out amillion tumour cells into blood vessels a day.million tumour cells into blood vessels a day.

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10. Tumour cells10. Tumour cellstraveltravel --

metastasismetastasis

What makes most What makes most tumours so lethal istumours so lethal istheir ability totheir ability to

metastasizemetastasize ---- that is,that is,establish new tumourestablish new tumoursites at other locationssites at other locationsthroughout the body.throughout the body.Secondary tumoursSecondary tumours..

Metastasis is nowMetastasis is nowunderway, as tumourunderway, as tumourcells from the originalcells from the originalcancer growth travelcancer growth travelthroughout the body.throughout the body.Most of these cells willMost of these cells willdie soon after enteringdie soon after enteringthe blood or lymphthe blood or lymphcirculation.circulation.

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11. Metastasis11. Metastasis

To form aTo form a secondary tumoursecondary tumour, a tumour cell needs to, a tumour cell needs toleave the vessel system and invade tissue. The cell must leave the vessel system and invade tissue. The cell must

attach itself attach itself to a vessel's wall. Once this is done, it canto a vessel's wall. Once this is done, it canwork its way through the vessel and enter the tissue.work its way through the vessel and enter the tissue.

Although perhaps less than one in 10,000 tumour cells Although perhaps less than one in 10,000 tumour cellswill survive long enough to establish a new tumour site,will survive long enough to establish a new tumour site,a few survivors can escape and initiatea few survivors can escape and initiate new coloniesnew colonies of of

the cancer.the cancer.

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