CancerCancer• Some cells, instead of leaving the cell cycle to

die, divide repeatedly and excessively, forming a clump of cells called a tumour.

• 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 An estimated 171,000171,000 new new cases of cancer (excluding cases of cancer (excluding 75,100 non-melanoma skin 75,100 non-melanoma skin

cancers), and cancers), and 75,300 deaths 75,300 deaths from cancerfrom cancer

are expected to occur are expected to occur in Canada in in Canada in each year. each year.

About About 40 per cent40 per cent of of Canadian women and Canadian women and 45 45

per centper cent of men of men will will develop cancerdevelop cancer during during

their lifetimes. their lifetimes.

About 24 per cent of About 24 per cent of women and 29 per cent women and 29 per cent

of men, or approximately of men, or approximately one out of fourone out of four

Canadians, is expected Canadians, is expected to die from cancer. to die from cancer.

• 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 travelled and grown in other areas

Three Tumour Types

Different Kinds of Cancer

Fat

Bone

Muscle

Lymphomas:

Leukemias:Some common carcinomas:

Lung

Breast (women)

Colon

Prostate (men)

Bladder

Lymph nodes

Bloodstream

Some common sarcomas:

Q1: Do you know someone personally that has had cancer?

A: Yes

B: No

Loss of Normal Growth ControlLoss of Normal Growth Control

Cancer cell division

Cancer cell division

Fourth orlater mutation

Fourth orlater mutation

Third mutation

Third mutation

Second mutationSecond

mutationFirst

mutationFirst

mutation

Uncontrolled growthUncontrolled growth

Cell Suicide or ApoptosisCell Suicide or Apoptosis

Cell damage—no repair

Cell damage—no repair

Normal cell division

Normal cell division

Example of Normal GrowthExample of Normal Growth

Cell migration

Cell migrationDermisDermis

Dividing cells in basal layer

Dividing cells in basal layer

Dead cells shed from

outer surface

Dead cells shed from

outer surface

EpidermisEpidermis

The Beginning of Cancerous GrowthThe Beginning of Cancerous Growth

Underlying tissueUnderlying tissue

Invasion and MetastasisInvasion and Metastasis

3Cancer cells reinvade

and grow at new location

3Cancer cells reinvade

and grow at new location

1Cancer cells invade

surrounding tissues and blood vessels

1Cancer cells invade

surrounding tissues and blood vessels

2Cancer cells are

transported by the circulatory system to

distant sites

2Cancer cells are

transported by the circulatory system to

distant sites

Malignant versus Benign TumorsMalignant versus Benign Tumors

TimeTime

Malignant (cancer) cells invade

neighboring tissues, enter blood vessels, and metastasize to

different sites

Benign (not cancer) tumor cells grow only locally and

cannot spread by invasion or metastasis

Cancer Tends to Involve Multiple MutationsCancer Tends to Involve Multiple Mutations

Malignant cells invade neighboring tissues, enter

blood vessels, and metastasize to different sites

Malignant cells invade neighboring tissues, enter

blood vessels, and metastasize to different sites

More mutations, more genetic

instability, metastatic

disease

More mutations, more genetic

instability, metastatic

disease

Proto-oncogenes mutate to oncogenes

Proto-oncogenes mutate to oncogenes

Mutations inactivate

DNA repair genes

Mutations inactivate

DNA repair genes

Cells proliferate

Cells proliferate

Mutation inactivates suppressor

gene

Mutation inactivates suppressor

gene

Benign tumor cells grow only locally and

cannot spread by invasion or metastasis

Benign tumor cells grow only locally and

cannot spread by invasion or metastasis

TimeTime

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 DangerousWhy Cancer Is Potentially Dangerous

Melanoma cells travel through bloodstream

Melanoma cells travel through bloodstream

Melanoma(initial tumor)

Melanoma(initial tumor)

BrainBrain

LiverLiver

Microscopic Appearance of Cancer CellsMicroscopic Appearance of Cancer Cells

What Causes Cancer?What Causes Cancer?Some viruses or bacteriaSome viruses or bacteria

HeredityDiet

Hormones

HeredityDiet

Hormones

RadiationRadiationSome chemicalsSome chemicals

•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.

Mutations

Tumour suppressor geneTumour 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.

•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.

From Benign to Malignant

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

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

Treatment Options

26

TaxolTaxolOne 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

27

Cancer Detectionand Treatment

Cancer Detectionand Treatment

Earlier detection and treatment of cancer greatly increase the

odds of survival.

Therefore, knowing the warning signs of cancer is important

to health.

C hange in bowel or bladder habits

A sore that does not heal

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 hoarseness

Population-Based StudiesPopulation-Based Studies

CANADA:LeukemiaCANADA:Leukemia

Regions of Highest IncidenceRegions of Highest Incidence

BRAZIL:Cervicalcancer

BRAZIL:Cervicalcancer

U.S.:Coloncancer

U.S.:Coloncancer

AUSTRALIA:Skin

cancer

AUSTRALIA:Skin

cancer

CHINA:Liver

cancer

CHINA:Liver

cancer

U.K.:Lung

cancer

U.K.:Lung

cancer

JAPAN:Stomachcancer

JAPAN:Stomachcancer

Heredity? Behaviors? Other Factors?Heredity? Behaviors? Other Factors?

100

50

50

100

50

50

Stomach Cancer(Number of new cases

per 100,000 people)

Stomach Cancer(Number of new cases

per 100,000 people)

U.S.U.S.JapanJapan Japanese familiesin U.S.

Japanese familiesin U.S.

100

70

70

100

70

70

Colon Cancer(Number of new cases

per 100,000 people)

Colon Cancer(Number of new cases

per 100,000 people)

U.S.U.S.JapanJapan Japanese familiesin U.S.

Japanese familiesin U.S.

Tobacco Use and CancerTobacco Use and CancerSome Cancer-Causing Chemicals in Tobacco SmokeSome Cancer-Causing Chemicals in Tobacco Smoke

Lag TimeLag Time

4000

3000

2000

1000

4000

3000

2000

1000

20-Year Lag Time Between Smoking and Lung Cancer20-Year Lag Time Between Smoking and Lung Cancer

CigarettesSmoked

per Personper Year

CigarettesSmoked

per Personper Year

Lung Cancer Deaths (per

100,000 people)

Lung Cancer Deaths (per

100,000 people)

YearYear

Lung cancer (men)

Lung cancer (men)

Cigarette consumption (men)

Cigarette consumption (men)

1900 1920 1940 1960 19801900 1920 1940 1960 1980

150

100

50

150

100

50

Avoid TobaccoAvoid Tobacco

15x

10x

5x

15x

10x

5x

Non-smokerNon-smokerCigarettes Smoked per DayCigarettes Smoked per Day

Lung Cancer Risk Increases with Cigarette ConsumptionLung Cancer Risk Increases with Cigarette Consumption

Lung Cancer

Risk

Lung Cancer

Risk

0 15 300 15 30

VirusesViruses

Virus inserts and changes

genes forcell growth

Virus inserts and changes

genes forcell growth

Cancer-linked virusCancer-linked virus

Examples of Human Cancer VirusesExamples of Human Cancer Viruses

Some Viruses Associated with Human CancersSome Viruses Associated with Human Cancers

Avoid Cancer VirusesAvoid Cancer Viruses

Noninfected women

Noninfected women

HPV Infection Increases Risk for Cervical CancerHPV Infection Increases Risk for Cervical Cancer

Cervical Cancer

Risk

Cervical Cancer

Risk

LowLow

HighHigh

Women infected with HPV

Women infected with HPV

Limit Alcohol and Tobacco Limit Alcohol and Tobacco

40x

30x

20x

10x

40x

30x

20x

10x

Alcoholic Drinks Consumed per Day

Alcoholic Drinks Consumed per Day

Packs of Cigarettes Consumed per DayPacks of Cigarettes Consumed per Day

Combination of Alcohol and Cigarettes Increases Risk for Cancer of the Esophagus

Combination of Alcohol and Cigarettes Increases Risk for Cancer of the Esophagus

Risk Increase

Risk Increase

ANDAND

Diet: Limit Fats and CaloriesDiet: Limit Fats and Calories

00

Number of Cases (per 100,000

people)

Number of Cases (per 100,000

people)

Grams (per person per day)Grams (per person per day)

Correlation Between Meat Consumption and Colon Cancer Rates in Different Countries

Correlation Between Meat Consumption and Colon Cancer Rates in Different Countries

4040

3030

2020

1010

3003002002001001008080

Diet: Consume Fruits and VegetablesDiet: Consume Fruits and Vegetables

Protect Yourself From Excessive SunlightProtect Yourself From Excessive Sunlight

Avoid Carcinogens Avoid Carcinogens

Some Carcinogens in the WorkplaceSome Carcinogens in the Workplace