CANCERCANCERBY DR. ASHFAQ BY DR. ASHFAQ

AFRIDIAFRIDI

Canc

erCa

ncer

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

cancercancer 1 in 17 deaths are due to

1 in 17 deaths are due to

lung cancerlung 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

common cancer in womenwomen There are over 100

There are over 100 different forms of cancer

different forms of cancer

Canc

erCa

ncer

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

only formed for growth or to replace dead ones.

or to replace dead ones. Cancerous cells divide

Cancerous cells divide repeatedly out of control

repeatedly out of control

even though they are

even though they are not needed, they crowd

not needed, they crowd out other normal cells

out other normal cells and function abnormally.

and function abnormally.

They can also destroy

They can also destroy the correct functioning

the correct functioning of major organs.of major organs.

Wha

t cau

ses

Wha

t cau

ses

canc

er?

canc

er?

Cancer arises from the Cancer arises from the mutationmutation of a normal gene. of a normal gene.

Mutated genes that cause Mutated genes that cause cancer are called cancer are called oncogenesoncogenes..

It is thought that several It is thought that several mutations need to occur to mutations need to occur to give rise to cancergive rise to cancer

Cells that are old or not Cells that are old or not functioning properly functioning properly normally self destruct and normally self destruct and are replaced by new cells.are replaced by new cells.

However, cancerous cells However, cancerous cells do not self destruct and do not self destruct and continue to divide rapidly continue to divide rapidly producing millions of new producing millions of new cancerous cells.cancerous cells.

A factor which brings A factor which brings about a mutation is called about a mutation is called a a mutagen.mutagen.

A mutagen is A mutagen is mutagenic.mutagenic.

Any agent that causes Any agent that causes cancer is called a cancer is called a carcinogencarcinogen and is and is described as described as carcinogeniccarcinogenic..

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

Carc

inoge

ns

Carc

inoge

ns

Ionising radiationIonising radiation – X Rays, UV – X Rays, UV lightlight

ChemicalsChemicals – tar from – tar from cigarettescigarettes

Virus infectionVirus infection – papilloma – papilloma virus can be responsible for virus can be responsible for cervical cancer.cervical cancer.

Hereditary predispositionHereditary predisposition – – Some families are Some families are more more susceptiblesusceptible to getting certain to getting certain cancers. Remember cancers. Remember you can’t you can’t inherit cancerinherit cancer its just that you its just that you maybe more susceptible to maybe more susceptible to getting it.getting it.

Benig

n or

Benig

n or

malign

ant?

malign

ant?

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

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

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

Both types of tumour can tire Both types of tumour can tire the body out as they both the body out as they both need a huge amount of need a huge amount of nutrients to sustain the rapid nutrients to sustain the rapid growth and division of the growth and division of the cells.cells.

The

Th

e De

velo

pmen

t of

Deve

lopm

ent o

f Ca

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Canc

er

Within every nucleus

Within every nucleus of every one of the

of every one of the human body's 30

human body's 30 trillion cells exists

trillion cells exists DNA, the substance

DNA, the substance that contains the

that contains the information needed to

information needed to make and control

make and control every cell within the

every cell within the body. Here is a close-

body. Here is a close-up view of a tiny

up view of a tiny fragment of DNA.

fragment of DNA.

1. DNA of a normal

1. DNA of a normal cellcell

This piece of DNA is an exact copy of the DNA

This piece of DNA is an exact copy of the DNA

from which it came. When the parent cell divided

from which it came. When the parent cell divided

to create two cells, the cell's DNA also divided,

to create two cells, the cell's DNA also divided,

creating two identical copies of the original DNA.

creating two identical copies of the original DNA.

2. Muta

tion o

f

2. Muta

tion o

f

DNADNA

Here is the same section of DNA Here is the same section of DNA but from another cell. If you can but from another cell. If you can imagine that DNA is a twisted imagine that DNA is a twisted ladder, then each rung of the ladder, then each rung of the ladder is a pair of joined ladder is a pair of joined molecules, or a base pair. With molecules, or a base pair. With this section of DNA, one of the this section of DNA, one of the base pairs is different from the base pairs is different from the original. original. This DNA has suffered a This DNA has suffered a mutationmutation, either through mis-, either through mis-copying (when its parent cell copying (when its parent cell divided), or through the divided), or through the damaging effects of exposure damaging effects of exposure to to radiation or a chemical radiation or a chemical carcinogen.carcinogen.

3. Ge

netic

ally a

ltere

d

3. Ge

netic

ally a

ltere

d ce

llce

ll

Body cells replicate Body cells replicate through mitosis, they through mitosis, they respond to their respond to their surrounding cells and surrounding cells and replicate only to replace replicate only to replace other cells. Sometimes a other cells. Sometimes a genetic mutationgenetic mutation will will cause a cell and its cause a cell and its descendants to reproduce descendants to reproduce even though replacement even though replacement cells are not needed.cells are not needed.The DNA of the cell The DNA of the cell highlighted above has a highlighted above has a mutationmutation that causes the that causes the cell to replicate even cell to replicate even though this tissue doesn't though this tissue doesn't need replacement cells at need replacement cells at this time or at this place.this time or at this place.

4. S

prea

d an

d se

cond

4. S

prea

d an

d se

cond

m

utat

ionm

utat

ion The genetically altered cells have, The genetically altered cells have,

over time, over time, reproduced uncheckedreproduced unchecked, , crowding out the surrounding crowding out the surrounding normal cells. The growth may normal cells. The growth may contain one million cells and be contain one million cells and be the size of a pinhead. At this point the size of a pinhead. At this point the cells continue to look the the cells continue to look the same as the surrounding healthy same as the surrounding healthy cells. cells. After about a million divisions, After about a million divisions, there's a good chance that one of there's a good chance that one of the new cells will have the new cells will have mutated mutated furtherfurther. This cell, now carrying two . This cell, now carrying two mutant genesmutant genes, could have an , could have an altered appearancealtered appearance and be even and be even more prone to reproduce more prone to reproduce unchecked.unchecked.

5. Third

5. Third

mutation

mutation

Not all mutations that lead to Not all mutations that lead to cancerous cells result in the cells cancerous cells result in the cells reproducing at a faster, more reproducing at a faster, more uncontrolled rate. For example, a uncontrolled rate. For example, a mutation may simply cause a cell mutation may simply cause a cell to keep from self-destructing. All to keep from self-destructing. All normal cells have surveillance normal cells have surveillance mechanisms that look for damage mechanisms that look for damage or for problems with their own or for problems with their own control systems. If such problems control systems. If such problems are found, the cell destroys itself.are found, the cell destroys itself.Over time and after many cell Over time and after many cell divisions, a divisions, a third mutationthird mutation may may arise. If the mutation gives the arise. If the mutation gives the cell some further advantage, that cell some further advantage, that cell will grow more vigorously than cell will grow more vigorously than its predecessors and thus speed its predecessors and thus speed up the up the growth of the tumourgrowth of the tumour..

6. Fourth

6. Fourth

mutation

mutation

The new type of cells g

row rapidly,

The new type of cells g

row rapidly,

allowing for more opportunities fo

r

allowing for more opportunities fo

r

mutations. The next m

utation

mutations. The next m

utation

paves the way for th

e

paves the way for th

e

development of an even more

development of an even more

aggressive cancer

aggressive cancer. .

At this p

oint the tumour is

still

At this p

oint the tumour is

still

contained

contained..

7. Br

eakin

g thro

ugh

7. Br

eakin

g thro

ugh

the m

embr

ane

the m

embr

ane

The newer, wilder cells The newer, wilder cells created by another mutation created by another mutation are able to are able to push their way push their way through the epithelial tissue's through the epithelial tissue's basement membranebasement membrane, which , which is a meshwork of protein that is a meshwork of protein that normally creates a barrier. normally creates a barrier. The invasive cells in this The invasive cells in this tumour are tumour are no longer no longer containedcontained. .

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

8. 8.

Angio

gene

sis

Angio

gene

sis

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

Without blood and the nutrients it Without blood and the nutrients it carries, a tumour would be carries, a tumour would be unable to continue growing. With unable to continue growing. With the new blood supply, however, the new blood supply, however, the the growth of the tumour growth of the tumour acceleratesaccelerates; it soon contains ; it soon contains thousand million cellsthousand million cells and, now and, now the size of a small grape, is large the size of a small grape, is large enough to be detected as a lump enough to be detected as a lump

9.Inv

asion

and

9.Inv

asion

and

dispe

rsal

dispe

rsal The tumour has now The tumour has now invaded invaded

the tissuethe tissue beyond the beyond the basement membrane.basement membrane.

Individual cells from the Individual cells from the tumour enter into the network tumour enter into the network of newly formed blood vesselsof newly formed blood vessels, , using these vessels as using these vessels as highways by which they can highways by which they can move to other parts of the move to other parts of the body. A tumour as small as a body. A tumour as small as a gram can send out a million gram can send out a million tumour cells into blood vessels tumour cells into blood vessels a day.a day.

10. T

umou

r cell

s

10. T

umou

r cell

s

trave

l - m

etas

tasis

trave

l - m

etas

tasis

What makes most tumours What makes most tumours so lethal is their ability to so lethal is their ability to metastasize metastasize -- that is, -- that is, establish new tumour sites establish new tumour sites at other locations at other locations throughout the body.throughout the body.Secondary tumoursSecondary tumours..

Metastasis is now Metastasis is now underway, as tumour cells underway, as tumour cells from the original cancer from the original cancer growth travel throughout growth travel throughout the body. Most of these the body. Most of these cells will die soon after cells will die soon after entering the blood or entering the blood or lymph circulation.lymph circulation.

11.

11.

Meta

stasis

Meta

stasis

To form a To form a secondary tumoursecondary tumour, a , a tumour cell needs to leave the tumour cell needs to leave the vessel system and invade vessel system and invade tissue. The cell must tissue. The cell must attach attach itselfitself to a vessel's wall. Once to a vessel's wall. Once this is done, it can work its this is done, it can work its way through the vessel and way through the vessel and enter the tissue. enter the tissue. Although perhaps less than Although perhaps less than one in 10,000 tumour cells will one in 10,000 tumour cells will survive long enough to survive long enough to establish a new tumour site, a establish a new tumour site, a few survivors can escape and few survivors can escape and initiate initiate new coloniesnew colonies of the of the cancer.cancer.

THANKS