Cancer is one of the most common diseases in the developed world, with 1 in 4 deaths due to cancer and 1 in 17 due to lung cancer. Cancer occurs due to mutations in genes that control cell division, causing cells to divide uncontrollably and form tumors. Factors that can cause these mutations include ionizing radiation, chemicals like cigarette tar, and virus infections. As more mutations accumulate, tumors can grow larger and eventually spread via the bloodstream or lymphatics to form secondary tumors in other parts of the body.

1. CANCER
CANCER
BY DR. ASHFAQ
BY DR. ASHFAQ
AFRIDI
AFRIDI

2. Cancer
Cancer
 Cancer is one of the most
Cancer is one of the most
common diseases in the
common diseases in the
developed world:
developed world:
 1 in 4 deaths are due to
1 in 4 deaths are due to
cancer
cancer 1 in 17 deaths are due to
1 in 17 deaths are due to
lung cancer
lung cancer Lung cancer is the most
Lung cancer is the most
common cancer in men
common cancer in men
 Breast cancer is the most
Breast cancer is the most
common cancer in women
common cancer in women
 There are over 100
There are over 100
different forms of cancer
different forms of cancer

3. Cancer
Cancer
 The division of normal
The division of normal
cells is precisely
cells is precisely
controlled. New cells are
controlled. New cells are
only formed for growth or
only formed for growth or
to replace dead ones.
to replace dead ones.
 Cancerous cells divide
Cancerous cells divide
repeatedly out of control
repeatedly out of control
even though they are not
even though they are not
needed, they crowd out
needed, they crowd out
other normal cells and
other normal cells and
function abnormally.They
function abnormally.They
can also destroy the
can also destroy the
correct functioning of
correct functioning of
major organs.
major organs.

4. Whatcausescancer?
Whatcausescancer?
Cancer arises from theCancer arises from the
mutationmutation of a normal gene.of a normal gene.
Mutated genes that causeMutated genes that cause
cancer are calledcancer are called oncogenesoncogenes..
It is thought that severalIt is thought that several
mutations need to occur tomutations need to occur to
give rise to cancergive rise to cancer
Cells that are old or notCells that are old or not
functioning properly normallyfunctioning properly normally
self destruct and are replacedself destruct and are replaced
by new cells.by new cells.
However, cancerous cells doHowever, cancerous cells do
not self destruct and continuenot self destruct and continue
to divide rapidly producingto divide rapidly producing
millions of new cancerousmillions of new cancerous
cells.cells.

5.  A factor which brings aboutA factor which brings about
a mutation is called aa mutation is called a
mutagen.mutagen.
 A mutagen isA mutagen is mutagenic.mutagenic.
 Any agent that causes cancerAny agent that causes cancer
is called ais called a carcinogencarcinogen and isand is
described asdescribed as carcinogeniccarcinogenic..
 So some mutagens areSo some mutagens are
carcinogenic.carcinogenic.

6. Carcinogens
Carcinogens
Ionising radiationIonising radiation – X Rays, UV– X Rays, UV
lightlight
ChemicalsChemicals – tar from cigarettes– tar from cigarettes
Virus infectionVirus infection – papilloma– papilloma
virus can be responsible forvirus can be responsible for
cervical cancer.cervical cancer.
Hereditary predispositionHereditary predisposition ––
Some families areSome families are moremore
susceptiblesusceptible to getting certainto getting certain
cancers. Remembercancers. Remember you can’tyou can’t
inherit cancerinherit cancer its just that youits just that you
maybe more susceptible tomaybe more susceptible to
getting it.getting it.

7. Benignormalignant?
Benignormalignant?
 Benign tumoursBenign tumours do not spreaddo not spread
from their site of origin, but canfrom their site of origin, but can
crowd out (squash) surroundingcrowd out (squash) surrounding
cells eg brain tumour, warts.cells eg brain tumour, warts.
 Malignant tumoursMalignant tumours can spreadcan spread
from the original site and causefrom the original site and cause
secondary tumourssecondary tumours.This is.This is
calledcalled metastasismetastasis.They interfere.They interfere
with neighbouring cells and canwith neighbouring cells and can
block blood vessels, the gut,block blood vessels, the gut,
glands, lungs etc.glands, lungs etc.
 Why are secondary tumours soWhy are secondary tumours so
bad?bad?
 Both types of tumour can tire theBoth types of tumour can tire the
body out as they both need abody out as they both need a
huge amount of nutrients tohuge amount of nutrients to
sustain the rapid growth andsustain the rapid growth and
division of the cells.division of the cells.

8. TheDevelopment
TheDevelopmentofCancer
ofCancer
Within every nucleus of
Within every nucleus of
every one of the human
every one of the human
body's 30 trillion cells
body's 30 trillion cells
exists DNA, the
exists DNA, the
substance that contains
substance that contains
the information needed
the information needed
to make and control
to make and control
every cell within the
every cell within the
body. Here is a close-up
body. Here is a close-up
view of a tiny fragment of
view of a tiny fragment of
DNA.
DNA.

9. 1. DNA of a normal cell
1. DNA of a normal cell
 This piece of DNA is an exact copy of the DNA from
This piece of DNA is an exact copy of the DNA from
which it came.When the parent cell divided to create
which it came.When the parent cell divided to create
two cells, the cell's DNA also divided, creating two
two cells, the cell's DNA also divided, creating two
identical copies of the original DNA.
identical copies of the original DNA.

10. 2.M
utation
of DNA
2.M
utation
of DNA
 Here is the same section of DNAHere is the same section of DNA
but from another cell. If you canbut from another cell. If you can
imagine that DNA is a twistedimagine that DNA is a twisted
ladder, then each rung of theladder, then each rung of the
ladder is a pair of joinedladder is a pair of joined
molecules, or a base pair.With thismolecules, or a base pair.With this
section of DNA, one of the basesection of DNA, one of the base
pairs is different from the original.pairs is different from the original.
This DNA has suffered aThis DNA has suffered a mutationmutation,,
either through mis-copying (wheneither through mis-copying (when
its parent cell divided), or throughits parent cell divided), or through
the damaging effects of exposurethe damaging effects of exposure
toto radiation or a chemicalradiation or a chemical
carcinogen.carcinogen.

11. 3.Geneticallyalteredcell
3.Geneticallyalteredcell
Body cells replicate throughBody cells replicate through
mitosis, they respond tomitosis, they respond to
their surrounding cells andtheir surrounding cells and
replicate only to replacereplicate only to replace
other cells. Sometimes aother cells. Sometimes a
genetic mutationgenetic mutation will causewill cause
a cell and its descendants toa cell and its descendants to
reproduce even thoughreproduce even though
replacement cells are notreplacement cells are not
needed.needed.
The DNA of the cellThe DNA of the cell
highlighted above has ahighlighted above has a
mutationmutation that causes the cellthat causes the cell
to replicate even though thisto replicate even though this
tissue doesn't needtissue doesn't need
replacement cells at thisreplacement cells at this
time or at this place.time or at this place.

12. 4.Spreadandsecond
4.Spreadandsecond
mutation
mutation
 The genetically altered cells have,The genetically altered cells have,
over time,over time, reproduced uncheckedreproduced unchecked,,
crowding out the surrounding normalcrowding out the surrounding normal
cells.The growth may contain onecells.The growth may contain one
million cells and be the size of amillion cells and be the size of a
pinhead. At this point the cellspinhead. At this point the cells
continue to look the same as thecontinue to look the same as the
surrounding healthy cells.surrounding healthy cells.
After about a million divisions, there'sAfter about a million divisions, there's
a good chance that one of the newa good chance that one of the new
cells will havecells will have mutated furthermutated further.This.This
cell, now carrying twocell, now carrying two mutant genesmutant genes,,
could have ancould have an altered appearancealtered appearance
and be even more prone to reproduceand be even more prone to reproduce
unchecked.unchecked.

13. 5.Third
m
utation
5.Third
m
utation
 Not all mutations that lead toNot all mutations that lead to
cancerous cells result in the cellscancerous cells result in the cells
reproducing at a faster, morereproducing at a faster, more
uncontrolled rate. For example, auncontrolled rate. For example, a
mutation may simply cause a cell tomutation may simply cause a cell to
keep from self-destructing. All normalkeep from self-destructing. All normal
cells have surveillance mechanismscells have surveillance mechanisms
that look for damage or for problemsthat look for damage or for problems
with their own control systems. If suchwith their own control systems. If such
problems are found, the cell destroysproblems are found, the cell destroys
itself.itself.
Over time and after many cellOver time and after many cell
divisions, adivisions, a third mutationthird mutation may arise.may arise.
If the mutation gives the cell someIf the mutation gives the cell some
further advantage, that cell will growfurther advantage, that cell will grow
more vigorously than itsmore vigorously than its
predecessors and thus speed up thepredecessors and thus speed up the
growth of the tumourgrowth of the tumour..

14. 6.Fourth
m
utation
6.Fourth
m
utation
The new
type of cells grow
rapidly,
The new
type of cells grow
rapidly,
allowing for more opportunities for
allowing for more opportunities for
mutations.The next mutation paves
mutations.The next mutation paves
the way for the development of an
the way for the development of an
even more
even more aggressive cancer
aggressive cancer..
At this point the tumour is still
At this point the tumour is still
contained
contained..

15. 7.Breakingthroughthe
7.Breakingthroughthe
membrane
membrane
 The newer, wilder cells createdThe newer, wilder cells created
by another mutation are able toby another mutation are able to
push their way through thepush their way through the
epithelial tissue's basementepithelial tissue's basement
membranemembrane, which is a meshwork, which is a meshwork
of protein that normally createsof protein that normally creates
a barrier.The invasive cells ina barrier.The invasive cells in
this tumour arethis tumour are no longerno longer
containedcontained..
At this point the cancer is stillAt this point the cancer is still
too small to be detectedtoo small to be detected..

16. 8.Angiogenesis
8.Angiogenesis
 Often during the development ofOften during the development of
earlier stages of the tumour, orearlier stages of the tumour, or
perhaps by the time the tumour hasperhaps by the time the tumour has
broken through the basementbroken through the basement
membrane (as pictured above),membrane (as pictured above),
angiogenesisangiogenesis takes place.takes place.
Angiogenesis is the recruitment ofAngiogenesis is the recruitment of
blood vessels from the network ofblood vessels from the network of
neighbouring vessels.neighbouring vessels.
 Without blood and the nutrients itWithout blood and the nutrients it
carries, a tumour would be unable tocarries, a tumour would be unable to
continue growing.With the newcontinue growing.With the new
blood supply, however, theblood supply, however, the growth ofgrowth of
the tumour acceleratesthe tumour accelerates; it soon; it soon
containscontains thousand million cellsthousand million cells and,and,
now the size of a small grape, isnow the size of a small grape, is
large enough to be detected as alarge enough to be detected as a
lumplump

17. 9.Invasionanddispersal
9.Invasionanddispersal
 The tumour has nowThe tumour has now invaded theinvaded the
tissuetissue beyond the basementbeyond the basement
membrane.membrane.
Individual cells from the tumourIndividual cells from the tumour
enter into the network of newlyenter into the network of newly
formed blood vesselsformed blood vessels, using these, using these
vessels as highways by which theyvessels as highways by which they
can move to other parts of thecan move to other parts of the
body. A tumour as small as a grambody. A tumour as small as a gram
can send out a million tumour cellscan send out a million tumour cells
into blood vessels a day.into blood vessels a day.

18. 10.Tumourcellstravel
10.Tumourcellstravel
-metastasis
-metastasis
What makes most tumours soWhat makes most tumours so
lethal is their ability tolethal is their ability to
metastasizemetastasize -- that is,-- that is,
establish new tumour sites atestablish new tumour sites at
other locations throughoutother locations throughout
the body.the body.
Secondary tumoursSecondary tumours..
Metastasis is now underway,Metastasis is now underway,
as tumour cells from theas tumour cells from the
original cancer growth traveloriginal cancer growth travel
throughout the body. Most ofthroughout the body. Most of
these cells will die soon afterthese cells will die soon after
entering the blood or lymphentering the blood or lymph
circulation.circulation.

19. 11.Metastasis
11.Metastasis
 To form aTo form a secondary tumoursecondary tumour, a, a
tumour cell needs to leave thetumour cell needs to leave the
vessel system and invade tissue.vessel system and invade tissue.
The cell mustThe cell must attach itselfattach itself to ato a
vessel's wall. Once this is done, itvessel's wall. Once this is done, it
can work its way through thecan work its way through the
vessel and enter the tissue.vessel and enter the tissue.
Although perhaps less than one inAlthough perhaps less than one in
10,000 tumour cells will survive10,000 tumour cells will survive
long enough to establish a newlong enough to establish a new
tumour site, a few survivors cantumour site, a few survivors can
escape and initiateescape and initiate new coloniesnew colonies
of the cancer.of the cancer.

20. THANKS