CancerCancer
 Cancer is one of the most common diseases inCancer is one of the most common diseases in
the developed worl...
CancerCancer
 The division of normal cells is preciselyThe division of normal cells is precisely
controlled. New cells ar...
What causes cancer?What causes cancer?
 Cancer arises from theCancer arises from the mutationmutation of a normalof a nor...
 A factor which brings about a mutation isA factor which brings about a mutation is
called acalled a mutagen.mutagen.
 A...
CarcinogensCarcinogens
 Ionising radiationIonising radiation – X Rays, UV light– X Rays, UV light
 ChemicalsChemicals – ...
Benign or malignant?Benign or malignant?
 Benign tumoursBenign tumours do not spread from their site of origin,do not spr...
The Development of CancerThe Development of Cancer
 Within every nucleus of every one of theWithin every nucleus of every...
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...
2. Mutation of DNA2. Mutation of DNA
 Here is the same section of DNA but from another cell. If youHere is the same secti...
3. Genetically altered cell3. Genetically altered cell
 Body cells replicate through mitosis, they respond toBody cells r...
4. Spread and second mutation4. Spread and second mutation
 The genetically altered cells have, over time,The genetically...
5. Third mutation5. Third mutation
 Not all mutations that lead to cancerous cells result in the cellsNot all mutations t...
6. Fourth mutation6. Fourth mutation
 The new type of cells grow rapidly, allowing forThe new type of cells grow rapidly,...
7. Breaking through the membrane7. Breaking through the membrane
 The newer, wilder cells created by another mutation are...
8. Angiogenesis8. Angiogenesis
 Often during the development of earlier stages of the tumour,Often during the development...
9.Invasion and dispersal9.Invasion and dispersal
 The tumour has nowThe tumour has now invaded the tissueinvaded the tiss...
10. Tumour cells10. Tumour cells
travel -travel -
metastasismetastasis
 What makes mostWhat makes most
tumours so lethal ...
11. Metastasis11. Metastasis
 To form aTo form a secondary tumoursecondary tumour, a tumour cell needs to, a tumour cell ...
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Cancer

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Cancer

  1. 1. 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 in womenwomen  There are over 100 different forms of cancerThere are over 100 different forms of cancer
  2. 2. CancerCancer  The division of normal cells is preciselyThe division of normal cells is precisely controlled. 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 crowd out other normal cells and function abnormally.out other normal cells and function abnormally. They can also destroy the correct functioning ofThey can also destroy the correct functioning of major organs.major organs.
  3. 3. 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 to occur to give rise to canceroccur to give rise to cancer  Cells that are old or not functioning properlyCells that are old or not functioning properly normally self destruct and are replaced bynormally self destruct and are replaced by new cells.new cells.  However, cancerous cells do not selfHowever, cancerous cells do not self destruct and continue to divide rapidlydestruct and continue to divide rapidly producing millions of new cancerous cells.producing millions of new cancerous cells.
  4. 4.  A factor which brings about a mutation isA factor which brings about a mutation is called acalled a mutagen.mutagen.  A mutagen isA mutagen is mutagenic.mutagenic.  Any agent that causes cancer is called aAny agent that causes cancer is called a carcinogencarcinogen and is described asand is described as carcinogeniccarcinogenic..  So some mutagens are carcinogenic.So some mutagens are carcinogenic.
  5. 5. CarcinogensCarcinogens  Ionising radiationIonising radiation – X Rays, UV light– X Rays, UV light  ChemicalsChemicals – tar from cigarettes– tar from cigarettes  Virus infectionVirus infection – papilloma virus can be– papilloma virus can be responsible for cervical cancer.responsible for cervical cancer.  Hereditary predispositionHereditary predisposition – Some families are– Some families are more susceptiblemore susceptible to getting certain cancers.to getting certain cancers. RememberRemember you can’t inherit canceryou can’t inherit cancer its just thatits just that you maybe more susceptible to getting it.you maybe more susceptible to getting it.
  6. 6. 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 brain tumour, warts.tumour, warts.  Malignant tumoursMalignant tumours can spread from the original sitecan spread from the original site and causeand cause secondary tumourssecondary tumours. This is called. This is called metastasismetastasis. They interfere with neighbouring cells and. They interfere with neighbouring cells and can 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 they both 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.
  7. 7. The Development of CancerThe Development of Cancer  Within every nucleus of every one of theWithin every nucleus of every one of the human body's 30 trillion cells exists DNA,human body's 30 trillion cells exists DNA, the substance that contains thethe substance that contains the information needed to make and controlinformation needed to make and control every cell within the body. Here is a close-every cell within the body. Here is a close- up view of a tiny fragment of DNA.up view of a tiny fragment of DNA.
  8. 8. 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. When the parent cell divided to createwhich it came. When the parent cell divided to create two cells, the cell's DNA also divided, creating twotwo cells, the cell's DNA also divided, creating two identical copies of the original DNA.identical copies of the original DNA.
  9. 9. 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 you can imagine that DNA is a twisted ladder, then each rung of thecan imagine that DNA is a twisted ladder, then each rung of the ladder is a pair of joined molecules, or a base pair. With thisladder is a pair of joined molecules, or a base pair. With this section 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-copying, either through mis-copying (when its parent cell divided), or through the damaging effects(when its parent cell divided), or through the damaging effects of exposure toof exposure to radiation or a chemical carcinogen.radiation or a chemical carcinogen.
  10. 10. 3. Genetically altered cell3. Genetically altered cell  Body cells replicate through mitosis, they respond toBody cells replicate through mitosis, they respond to their surrounding cells and replicate only to replacetheir surrounding cells and replicate only to replace other cells. Sometimes aother cells. Sometimes a genetic mutationgenetic mutation will cause awill cause a cell and its descendants to reproduce even thoughcell and its descendants to reproduce even though replacement 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 mutationmutation that causes the cell to replicate even though thisthat causes the cell to replicate even though this tissue doesn't need replacement cells at this time or attissue doesn't need replacement cells at this time or at this place.this place.
  11. 11. 4. Spread and second mutation4. Spread and second mutation  The genetically altered cells have, over time,The genetically altered cells have, over time, reproducedreproduced uncheckedunchecked, crowding out the surrounding normal cells. The, crowding out the surrounding normal cells. The growth may contain one million cells and be the size of agrowth may contain one million cells and be the size of a pinhead. 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 oneAfter about a million divisions, there's a good chance that one of the new cells will haveof the new cells will have mutated furthermutated further. This cell, now. This cell, now carrying twocarrying two mutant genesmutant genes, could have an, could have an altered appearancealtered appearance and be even more prone to reproduce unchecked.and be even more prone to reproduce unchecked.
  12. 12. 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 cells reproducing at a faster, more uncontrolled rate. For example, areproducing at a faster, more uncontrolled rate. For example, a mutation may simply cause a cell to keep from self-destructing.mutation may simply cause a cell to keep from self-destructing. All normal cells have surveillance mechanisms that look forAll normal cells have surveillance mechanisms that look for damage 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 maymay arise. If the mutation gives the cell some further advantage, thatarise. If the mutation gives the cell some further advantage, that cell will grow more vigorously than its predecessors and thuscell will grow more vigorously than its predecessors and thus speed up thespeed up the growth of the tumourgrowth of the tumour..
  13. 13. 6. Fourth mutation6. Fourth mutation  The new type of cells grow rapidly, allowing forThe new type of cells grow rapidly, allowing for more opportunities for mutations. The nextmore opportunities for mutations. The next mutation paves the way for the development ofmutation paves the way for the development of an even morean even more aggressive canceraggressive cancer.. At this point the tumour is still containedAt this point the tumour is still contained..
  14. 14. 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 are able toable to push their way through the epithelial tissue'spush their way through the epithelial tissue's basement membranebasement membrane, which is a meshwork of protein, which is a meshwork of protein that normally creates a barrier. The invasive cells in thisthat normally creates a barrier. The invasive cells in this tumour aretumour are no longer containedno longer contained.. At this point the cancer is stillAt this point the cancer is still too small to be detectedtoo small to be detected..
  15. 15. 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 the basement membrane (as pictured above),basement membrane (as pictured above), angiogenesisangiogenesis takestakes place.place. Angiogenesis is the recruitment of blood vessels fromAngiogenesis is the recruitment of blood vessels from the 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 be unable 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 soon containscontains thousand million cellsthousand million cells and, now the size of a smalland, now the size of a small grape, is large enough to be detected as a lumpgrape, is large enough to be detected as a lump
  16. 16. 9.Invasion and dispersal9.Invasion and dispersal  The tumour has nowThe tumour has now invaded the tissueinvaded the tissue beyond thebeyond the basement membrane.basement membrane. Individual cells from the tumour enter into the network ofIndividual cells from the tumour enter into the network of newly formed blood vesselsnewly formed blood vessels, using these vessels as, using these vessels as highways by which they can move to other parts of thehighways by which they can move to other parts of the body. A tumour as small as a gram can send out abody. A tumour as small as a gram can send out a million tumour cells into blood vessels a day.million tumour cells into blood vessels a day.
  17. 17. 10. Tumour cells10. Tumour cells travel -travel - metastasismetastasis  What makes mostWhat makes most tumours so lethal istumours so lethal is their ability totheir ability to metastasizemetastasize -- that is,-- that is, establish new tumourestablish new tumour sites at other locationssites at other locations throughout the body.throughout the body. Secondary tumoursSecondary tumours..  Metastasis is nowMetastasis is now underway, as tumourunderway, as tumour cells from the originalcells from the original cancer growth travelcancer growth travel throughout the body.throughout the body. Most of these cells willMost of these cells will die soon after enteringdie soon after entering the blood or lymphthe blood or lymph circulation.circulation.
  18. 18. 11. Metastasis11. Metastasis  To form aTo form a secondary tumoursecondary tumour, a tumour cell needs to, a tumour cell needs to leave the vessel system and invade tissue. The cell mustleave the vessel system and invade tissue. The cell must attach itselfattach itself to a vessel's wall. Once this is done, it canto a vessel's wall. Once this is done, it can work 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 cellsAlthough perhaps less than one in 10,000 tumour cells will survive long enough to establish a new tumour site, awill survive long enough to establish a new tumour site, a few survivors can escape and initiatefew survivors can escape and initiate new coloniesnew colonies of theof the cancer.cancer.
  19. 19. This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

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