Transcript Cancer

• Some cells, instead of leaving the cell cycle to die,
divide repeatedly and excessively, forming a clump
of cells called a tumour.
Cancer
• Cancer is a disease that eventually disrupts the
body functions, whereas a tumour is a mass of cells
with no apparent function in the body.
• Cancer is the uncontrolled division and spread of
abnormal cells.
An estimated 171,000 new cases
of cancer (excluding 75,100 nonmelanoma skin cancers), and
75,300 deaths from cancer
are expected to occur
in Canada in each year.
About 40 per cent of
Canadian women and 45 per
cent of men will develop
cancer during their lifetimes.
About 24 per cent of women
and 29 per cent of men, or
approximately one out of
four Canadians, is expected
to die from cancer.
Three Tumour Types
• Benign: (non cancerous) harmless
tumours that do not spread
• Malignant: harmful tumours that have the
potential to spread through the body
• Metastatic: tumours that have have
travelled and grown in other areas
Different Kinds of Cancer
Some common
carcinomas:
Leukemias:
Bloodstream
Lung
Lymphomas:
Breast (women)
Lymph nodes
Colon
Bladder
Prostate (men)
Some common
sarcomas:
Fat
Bone
Muscle
Q1: Do you know someone
personally that has had cancer?
A: Yes
B: No
Loss of Normal Growth Control
Normal
cell division
Cell Suicide or Apoptosis
Cell damage—
no repair
Cancer
cell division
First
mutation
Second
mutation
Third
mutation
Fourth or
later mutation
Uncontrolled growth
Example of Normal Growth
Dead cells
shed from
outer surface
Epidermis
Cell
migration
Dividing cells in
basal layer
Dermis
The Beginning of Cancerous Growth
Underlying tissue
Invasion and Metastasis
1
Cancer cells invade
surrounding tissues and
blood vessels
2
Cancer cells are
transported by the
circulatory system to
distant sites
3
Cancer cells reinvade
and grow at new
location
Malignant versus Benign Tumors
Benign (not cancer)
tumor cells grow
only locally and
cannot spread by
invasion or metastasis
Time
Malignant (cancer) cells
invade neighboring
tissues, enter blood
vessels, and metastasize
to different sites
Cancer Tends to Involve Multiple Mutations
Benign tumor cells
grow only locally and
cannot spread by
invasion or metastasis
Malignant cells invade
neighboring tissues, enter
blood vessels, and metastasize
to different sites
Time
Mutation
inactivates
suppressor
gene
Cells
proliferate
Mutations
Proto-oncogenes
inactivate mutate to oncogenes
DNA repair
genes
More mutations,
more genetic
instability,
metastatic
disease
Q2: Why might cancer
primarily affect older people
rather than young people?
A: Because the immune system of older people is not as effective in
distinguishing normal cells from cancer cells.
B: Because older people have been exposed to more carcinogens.
C: Because cancer develops after multiple mutations have occurred
which takes years to happen.
D: None of the above.
Why Cancer Is Potentially Dangerous
Brain
Melanoma cells
travel through
bloodstream
Liver
Melanoma
(initial tumor)
Microscopic Appearance of Cancer Cells
What Causes Cancer?
Some viruses or bacteria
Some chemicals
Radiation
Heredity
Diet
Hormones
Mutations
•Cancer arises from the accumulation of
genetic changes or mutations. Most cancers
have a minimum of 6-9 genes involved.
•People can be susceptible to cancer based
on their genetic makeup, but cancer isn’t
directly passed from parent to child.
•Many genes that are involved in cancer are
involved in regulating the cell cycle. Cancer
cells generally have multiple mutations before
control over cell division is lost.
Tumour suppressor gene
• A tumour supressor gene
like P53 controls or slows
the cell cycle and thus cell
division. When it is
mutated or absent, the cell
will divide uncontrollably.
• An oncogene is a gene
that when mutated will
lead to uncontrolled cell
division.
From Benign to Malignant
•Cancer cells divide too quickly and can leave the
original site and enter the blood, lymph, or
tissues.
•Most cells divide a set number (60-70) of times,
then they stop dividing.
•This usually limits benign tumors to small sizes.
•Cancer cells can divide indefinitely.
Treatment Options
Radiation - Uses high-energy rays to kill
cancer cells. A large machine directs radiation
at the body.
Chemotherapy - Uses anticancer drugs to kill
cancer cells.
Surgery - Physically removes cancer cells
Many patients will use combinations of these
Taxol
One common chemotherapy for
ovarian cancer is Taxol, which was
first isolated from Yew bark in 1962
by the National Cancer Institutes
(NCI).
Taxol blocks a cell's ability to break
down the mitotic spindle during
mitosis. With the spindle still in
place, the cell can't divide into
daughter cells and therefore the
cancer can’t grow.
Taxus Brevifolia
26
Cancer Detection
and Treatment
C hange in bowel or bladder
habits
A sore that does not heal
Earlier detection and
treatment of cancer
greatly increase the
odds of survival.
Therefore, knowing the
warning signs of cancer
is important to health.
U nusual bleeding or
discharge
T thickening or lump
I ndigestion or difficulty
swallowing
O bvious change in wart or
mole
N agging cough or
27
hoarseness
Population-Based Studies
Regions of Highest Incidence
U.K.:
Lung
cancer
JAPAN:
Stomach
cancer
CANADA:
Leukemia
U.S.:
Colon
cancer
CHINA:
Liver
cancer
AUSTRALIA:
Skin
cancer
BRAZIL:
Cervical
cancer
Heredity? Behaviors? Other Factors?
Colon Cancer
Stomach Cancer
(Number of new cases
per 100,000 people)
(Number of new cases
per 100,000 people)
100
100
70
50
7
0
5
0
Japan
Japanese
families
in U.S.
U.S.
Japan
Japanese
families
in U.S.
U.S.
Tobacco Use and Cancer
Some Cancer-Causing Chemicals in Tobacco Smoke
Lag Time
20-Year Lag Time Between
Smoking and Lung Cancer
Cigarette
consumption (men)
4000
3000
Cigarettes
Smoked
per Person
per Year
Lung
cancer
(men)
2000
150
100
50
1000
1900 1920 1940 1960 1980
Year
Lung Cancer
Deaths (per
100,000 people)
Avoid Tobacco
Lung Cancer Risk Increases
with Cigarette Consumption
15x
10x
Lung
Cancer
Risk
5x
0
Non-smoker
15
Cigarettes Smoked per Day
30
Viruses
Virus inserts
and changes
genes for
cell growth
Cancer-linked virus
Examples of Human Cancer Viruses
Some Viruses Associated with Human Cancers
Avoid Cancer Viruses
HPV Infection Increases
Risk for Cervical Cancer
High
Cervical
Cancer
Risk
Low
Noninfected
women
Women
infected
with HPV
Limit Alcohol and Tobacco
Combination of Alcohol and Cigarettes
Increases Risk for Cancer of the Esophagus
40x
30x
Risk
Increase 20x
10x
Alcoholic Drinks
Consumed per Day
AND
Packs of Cigarettes
Consumed per Day
Diet: Limit Fats and Calories
Correlation Between Meat Consumption and
Colon Cancer Rates in Different Countries
40
Number of Cases
(per 100,000
people)
30
20
10
0
80
100
200
300
Grams (per person per day)
Diet: Consume Fruits and Vegetables
Protect Yourself From Excessive Sunlight
Avoid Carcinogens
Some Carcinogens in the Workplace