Download Understanding Cancer

Understanding
Cancer
What Is Cancer?
 Cancer
is a large group
of diseases (over 200)
characterized by
uncontrolled growth and
spread of abnormal
cells.*
*American Cancer Society, Cancer Facts and Figures 2005
Normal Cells Vs. Cancer Cells

Cancer cells:
 Lose control over growth
and multiplication


Do not self-destruct when
they become worn out or
damaged
Crowd out healthy cells
What causes cancer?
Cancer arises from the mutation of a normal gene.
 Mutated genes that cause cancer are called
oncogenes.
 It is thought that several mutations need to occur
to give rise to cancer
 Cells that are old or not functioning properly
normally self destruct and are replaced by new
cells.
 However, cancerous cells do not self destruct and
continue to divide rapidly producing millions of
new cancerous cells.

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
Growth of Cancer Cells
 Cancer cells reproduce
every 2-6 weeks.
2-6 weeks

2-6 weeks
Size of cancer cells:
 One million cancer
cells = head of a pin


2-6 weeks
One billion cancer
cells = a small grape
230 = 1,073,741,824
= 1 billion cells
Benign or malignant?

Benign tumours do not spread from their site of origin, but
can crowd out (squash) surrounding cells eg brain tumour.

Malignant tumours can spread from the original site and
cause secondary tumours. This is called metastasis. They
interfere with neighbouring cells and can block blood
vessels, the gut, glands, lungs etc.

Why are secondary tumours so bad?

Both types of tumour can tire the body out as they both need
a huge amount of nutrients to sustain the rapid growth and
division of the cells.
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
Why Cancer Is Potentially Dangerous
Brain
Melanoma cells
travel through
bloodstream
Liver
Melanoma
(initial tumor)
Signs and Symptoms of
Cancer







Change in bowel habits or bladder functions
Sores that do not heal
Unusual bleeding or discharge
Lumps or thickening of breast or other parts of
the body
Indigestion or difficulty swallowing
Recent change in wart or mole
Persistent coughing or hoarseness
Types of Cancers
 Carcinomas (cells
that cover internal and
external body surfaces)
Lung
Breast
Leukemia
(Blood Cells)
Lymphomas
(Lymph nodes &tissues)
Colon
Bladder
Prostate
(Men)
Sarcomas
Cells in supportive
tissues – bones &
muscles
What Causes Cancer?
Family History
Lifestyle
Environment
Lifestyle Risks

Smoking

Diet high fat and low in
fruits and vegetables

Lack of exercise

Unprotected exposure
to the sun, (UV) rays

Obesity
Environmental Risks

Second hand smoke

Air pollution

Industrial pollution

Chemical exposures
Inherited Risks

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Less than 15% of
cancers are inherited
Gene mutations are
linked to some
inherited cancers
Cancers that may be
caused by inherited
gene mutations are:
 Colon cancer
 Breast cancer
 Ovarian
 Prostate cancer
 Skin cancer
Biological Factors
Some cancers such as breast, stomach,
colon, prostate, uterus, ovaries and lung
appear to run in families
 Hodgkin’s disease and certain leukemia's
show similar patterns
 University of Utah research suggests that a
gene for breast cancer exists
 A rare form of eye cancer appears to be
transmitted genetically from mother to child

Reproductive And Hormonal
Risks For Cancer
Pregnancy and oral contraceptives increase
a woman’s chances of breast cancer
 Late menarche, early menopause, early first
childbirth, having many children have been
shown to reduce risk of breast cancer

Occupational And Environmental
Factors
Asbestos
 Nickel
 Chromate
 Benzene
 Arsenic
 Radioactive substances
 Cool tars
 Herbicides/pesticides

Avoid Carcinogens at Work
Some Carcinogens in the Workplace
Social And Psychological Factors
Stress has been implicated in increased
susceptibility to several types of cancers
 Sleep disturbances, diet, or a combination
of factors may weaken the body’s immune
system

Chemicals In Foods
Sodium nitrate when ingested forms a
potential carcinogen, nitrosamine
 Sodium nitrate is still used because it is
effective in preventing botulism
 Pesticide and herbicide residues

Viral Factors
Herpes-related viruses may be involved in the
development of leukemia, Hodgkin’s disease,
cervical cancer, and Burkitt’s lymphoma
 Epstein-Barr virus, associated with
mononucleosis, may contribute to cancer
 Human papillomavirus (HPV), virus that
causes genital warts, has been linked to
cervical cancer
 Helicobacter pylori causes ulcers which are a
major factor in the development of stomach
cancer

Examples of Human Cancer
Viruses
Some Viruses Associated with Human Cancers
Medical Factors
Some medical treatments actually increase a
person’s risk for cancer
 Diethylstilbestrol (DES) used 1940 to 1960
to control bleeding during pregnancy, the
daughters of mothers that used DES were
found to have an increased risk for cancers
of the reproductive organs
 Estrogen supplementation
 Chemotherapy used to treat one form of
cancer may increase risk for another type of
cancer

Screening Tests and
Self-exams
Screening tests:
 Colon
 Breast
 Cervical
 Prostate
Self-exams:
 Testicular
 Skin
Why Screening Tests?
The treatment of cancer is
most successful when the
cancer is detected as early
as possible, often before
symptoms occur.
Colon Cancer


Most colon cancers
start as a polyp
• A polyp
Removing polyps
can prevent colon
cancer
• Advanced
bleeding
cancer
Cervical Cancer Screening
Normal
Pap smear
Abnormal
Pap smear
Breast Cancer Screening
Colon Cancer Screening
Colon Cancer Screening
Guidelines
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Age of 50 and older; younger if
there is a family history
Yearly fecal occult blood test (FOBT) or
Flexible sigmoidoscopy every 5 years or
Yearly FOBT and sigmoidoscopy (a procedure used
to see inside the sigmoid colon and rectum. The
sigmoid colon is the area of the large intestine
nearest the rectum) every 5 years
Colonoscopy every 10 years
Breast Cancer
Screening Guidelines
Yearly mammograms starting at age 40
and continuing for as long as a woman
is in good health.
 Clinical breast exams (CBE) should be
part of a periodic health exam, about
every three years for women in their 20s
and 30s and every year for women 40
and over.

Breast Cancer
Screening Guidelines

Women should report any breast change
promptly to their health care providers. Breast
self-exam (BSE) is an option for women for
women starting in their 20s.
 Women at increased risk (e.g., family history,
genetic tendency, past breast cancer ) should
talk with their doctors about the benefits and
limitations of starting mammography
screening earlier, having additional tests
(e.g., breast ultrasound or MRI), or having
more frequent exams.
Cervical Cancer
Screening Guidelines
Annual pap testing should
begin with the onset of
sexual activity or at age 18
 Investigate pros & cons of
new HPV vaccine
 Pap testing should continue
less frequently at the
discretion of the medical
provider and patient after
three or more annual tests
have been normal

Prostate Cancer
Screening Guidelines

Men should speak to their doctor about the
pros and cons of prostate cancer screening

Both prostate specific antigen (PSA) and
digital rectal examinations (DRE) are
recommended for men over 50 and who
choose to undergo screening for prostate
cancer
Testicular Cancer
Screening Guidelines

Doctors agree that examination of a man’s
testicles is an important part of a general
physical exam. It is recommended that a
testicular exam be conducted during routine
cancer-related checkups.

It is believed that it is important to make men
aware of testicular cancer and that any unusual
mass should be evaluated by a health care
provider immediately.
Skin Cancer

A
B
C
D
The ABCD’s of melanoma (skin
cancer):
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Asymmetry: one half is not like the
other
Border: the edges are jagged or
irregular
Color: the color is varied, tan, red,
black ect
Diameter: the diameter is larger than
8mm (the top of a pencil eraser
Skin Cancer Prevention

It is important to:
Protect your skin with hats, long sleeves
and sunscreen
 Do a self examination of your skin monthly
 Become familiar with any moles, freckles or
other abnormalities on your skin
 Check for changes once a month. Show
any suspicious or changing areas to your
health care provider.

Biopsy
Pathology
Proteomic profile
Patient’s
tissue sample or
blood sample
Genomic profile
How Far Have We Come ?
Five year survival rate:
 1913 - 10%

2003 - 66%

Advances in cancer
research continue
Avoid Smoking or Chewing
Tobacco
Cigarette smoking is the
leading cause of preventable
death in the US and Canada
 Second hand smoke affects
everyone

Tobacco Use and Cancer
Some Cancer-Causing Chemicals in Tobacco Smoke
Fruits and Vegetables
Decrease Cancer Risks
Cancer rates could
decline by up to
20% if everyone
consumed 5 fruits and
vegetables a day!*
 Cancer fighting
substances:

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*American Institute for Cancer Research, 1998.
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Antioxidants
Dietary fiber
Carotenoids
Flavenoids
Limit Alcohol to No More Than

Men – 2 drinks per
day

Women - 1 drink per
day
Reduce Your Skin Exposure to
the Sun

Limit time outside,
between 10 a.m. & 4 p.m.

Wear protective clothing.
Use wide-brimmed hats
and sunglasses.

Prevent sunburns,
especially for children
under 18. Use
waterproof sunscreen of
SPF 15 or higher.
Reapply as directed.

Avoid tanning beds.
Be Active…Often

Exercise for 30 minutes or
more at least 4 days a
week.
Population-Based Studies
Regions of Highest Incidence
U.K.:
Lung
cancer
JAPAN:
Stomach
cancer
CHINA:
Liver
cancer
AUSTRALIA:
Skin
cancer
CANADA:
Leukemia
U.S.:
Colon
cancer
BRAZIL:
Cervical
cancer