Download Unit # 6: Cancer

Unit # 6: Cancer
Overview
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2nd leading cause of death in Canada
29% of all mortality (2004)
Higher risk in people over 65, males
Leading cause of Potential Years of Life Lost
(PYLL)
– Ex. PYLL
• A man who has a life expectancy of 70 dies at age 65
from cancer, his PYLL = 70-65 = 5
New cases (A) and Deaths (B) by cancer type in
Males
A
B
New cases (A) and Deaths (B) by cancer type in
Females
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B
Incidence (A) and Mortality (B) rates
by age
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B
Incidence (bars) and Mortality rates
(line) for males (A) and females (B)
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B
Worldwide Trends
• Accounted for 7.4 million worldwide deaths
(2004)
• Expected to rise to 12 million by 2030
• Leading mortal cancers by gender:
– Men: lung, stomach, liver, oesophageal, prostate
– Women: breast, lung, stomach, colorectal, cervical
Mechanism of cancer:
How does it happen?
• Normal, healthy cells have genes which control:
• When they divide
• When they stop dividing
• When they die
• Repetitive exposure to certain agents can cause an
accumulation of mutations in these genes, and they lose
this control
• Cancer is a disease evidenced by:
uncontrolled cell growth and spread
Mechanism of cancer
The mutations that result in cancer
are caused by:
Carcinogens: cancer causing agent
Physical carcinogens: UV light, radiation
Chemical Carcinogens: asbestos,
chemical in tobacco smoke, arsenic
Biological carcinogens: viruses, bacteria,
parasites
Development of Cancer:
“Multiple hits” finally lead to a
genetic change
Main Genes Responsible for Cancer
• Proto-oncogens/oncogenes
• Proto-oncogenes regulate
–how often a cell divides
–how specialized it is (able to perform a particular
task)
• A mutation turns proto-oncogenes into oncogenes
and the cell no longer has regulated control over
division
• Summary: oncogenes are cancer _______________
genes and they are turned ______
Main Genes Responsible for Cancer
• Tumour Suppressor Genes
– normally function to suppress cancerous growth
by:
• Suppressing uncontrolled growth
• Repairing DNA mutations
• Telling the cell when to die
– Mutations can turn these genes off
• Summary: TSG’s are cancer _____________
genes, they are turned ____
Neoplasms
• Neoplasms are new growths in the body. They occur constantly.
These growths can form a dense group of cells called a
_____________________. Not all tumours are cancerous!
• Benign tumours are growths which are enclosed in a membrane.
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Still have control over growth
Do not invade
Do not metastasize (spread)
NOT CANCER!!!
• Malignant tumours are cancerous growths which are not
enclosed in a membrane
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No control over cellular growth
Invade
Metastasize
CANCER!!!
Metastatic tumours (Cancer)
Benign vs. Malignant tumour
Cancer Staging
• Overall Stage Grouping
– Stage 0: a growth that stays in place, no metastasis,
no invasion
– Stage 1: cancer localized to one area
– Stage 2: cancer is localized to one area, but is more
aggressive
– Stage 3: invasion into local areas and/or lymph nodes
– Stage 4: Metastatic cancer
Cancer Staging
ex. Prostate Cancer
Survival Rate
• Cancer is considered cured if patient lives five
years after original diagnosis
– Varies with the type of cancer.
• Ex. High with skin cancer, low with brain cancer
• Survival rate increases with EARLY DETECTION!
• However, cancer can have a very long latent
period
– latent period = time between first exposure to a
carcinogen (ex. Cigarette smoke) and the first signs
and symptoms showing (ex. Lung cancer)
Cancer Treatment in General
• Surgery
• Radiation
• Chemotherapy (drugs)
Cancer Treatment
• Cancer treatment is tailored to the individual.
Each case is different.
• A team of doctors will consider the: type, stage,
age, general health, medical problems of the
patient
• Will decide on the best course of action for that
specific patient
• Health Care spending for cancer treatment is a
huge burden on both the health care system
and the patient/their supporters
MAJOR TYPES OF CANCER
Male incidence rates for different
cancers
Male mortality rates for different
cancers
Female incidence rates for different
cancers
Female mortality rates for different
cancers
Lung Cancer
• Highest mortality rate of any cancer
• Rates are actually increasing in Canadian
females 
Lung Cancer Risk Factors
• Smoking is the leading risk factor
– Smokers are 10-20 times more likely to get lung cancer
than non-smoking population
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Asbestos
Arsenic
Exposure to Radon Gas
Family history
Previous case of lung cancer
Air pollution
Smoking and Lung Cancer
Lung Cancer
• Symptoms: chronic cough that worsens,
breathing problems, chronic chest pain, hoarse
voice
• 5-year survival rate: 13% (males); 17% (females)
• Screening: No effective screening exists!
Breast Cancer
Female Age-standardized incidence rates for breast cancer
Female Age-standardized mortality rates for breast cancer
What does this suggest??????
Breast cancer risk factors
• Females are at much higher risk
• Males = less than 1%
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Previous breast cancer
Family history
Family history of ovarian cancer
Above average estrogen exposure (promotes cancerous
growth!)
• Early menstruation and late menopause
• Never given birth, first child after 60
• Older Age
• Also: obesity, alcohol, birth control pills may slightly
increase your risk
Breast Cancer
• Signs and symptoms: lump, changes in breast
size/shape, dimpling, puckering of skin,
redness, inverted nipple
• 5-year survival rate: 84% (women); 87%
(men)
• Screening: multi-stage screening; highly
effective!
Breast Cancer Screening
• Breast self-examination
• Mammography a low dose breast X-ray
• Multi-stage screening:
– Involves an initial general screening test, then
subsequent diagnostic tests become more and
more specific
– Note: screening is done on healthy populations,
testing is done on people who already have the
disease
Multi-level screening
Prostate Cancer
Prostate cancer risk factors
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Age
Family history
African ancestry
Also: obesity, physical inactivity, high fat diet,
very excessive calcium intake may slightly
increase risk (all are currently being studied
more)
Prostate cancer
• Signs and symptoms: frequent/urgent
urination, difficulty with the control of urine
flow, inability to urinate, burning/pain
urinating, painful ejaculation.
– Often NO symptoms are evident! Extremely
important to SCREEN!!! Do not ignore any of the
above symptoms!
• 5-year survival rate: 95% with early detection
• Screening: PSA test, digital rectal exam
Colorectal Cancer
Colorectal cancer risk factors
• Age (50+)
• Appearance of polyps (small growth on inner wall
of colon/rectum)
• Family history
• Inflammatory bowel diseases
• Diet high in red meat, processed meat, alcohol
• Smoking
• Physical inactivity
• Obesity
• Diet low in vegetables and fruits, fibre
Colorectal Cancer
• Signs and symptoms: change in bowel
movements, blood in stool, diarrhea,
constipation, narrow stools, abdominal pain,
unexplained weight loss
• 5-year survival rate: 61% (males), 62% (women)
• Screening: People over 50 are recommended to
have a fecal occult blood test (FOBT) every 2
years minimum
Cervical Cancer
Cervical cancer risk factors
• Infrequent Pap tests
• Sexual activity (young, frequent, multiple
partners)
• Smoking
• Weakened immune system
• Long term use of birth control pills
• Having many children
Cervical Cancer
• Signs/symptoms: abnormal vaginal bleeding,
bleeding between cycles, longer
menstruation, increased vaginal discharge,
pain in pelvis/during intercourse
• Early detection: Pap test! Get it!
Skin Cancer
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Most commonly diagnosed cancer
Easy to treat since it’s on the surface
It rarely metastasizes
Basal cell carcinoma= most common, easier to
treat
• Malignant melanoma= more aggressive,
metastasizes
Skin cancer risk factors
(melanoma)
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UV exposure (sunlight/tanning beds)
Unusual moles
Large amount of moles
Light skin, eyes, hair
Skin that burns/freckles easily
History of melanoma
Family history
Severe sunburn during childhood
Skin cancer
• Signs/symptoms: new/unusual looking skin
growths, itchy moles, ABCD moles (see figure,
next slide)
• 5-year survival rate: depends on the type of skin
cancer/ when it is discovered. If skin cancer is
discovered and treated before it spreads, survival
rate close to 100%!
• Early detection: look for the signs/symptoms of
skin cancer, namely the change in appearance of
moles
How to Spot Skin Cancer:
ABCD
Blood Cancers
• Not strongly correlated with increased age,
affects young and old
• There are many types of cancers that affect
the blood. They are named for the type of
blood tissue they affect:
– Leukemia: affects leukocytes (white blood cells)
– Lymphoma: affects lymphocytes (ie. B/T cells)
– Myeloma: affects plasma cells (recall, become B
cells)
Blood Cancers
• Cause is unknown!!! 
• Signs/symptoms: not always obvious! May notice
chronic fever, unexplained weight loss, tiredness,
shortness of breath, bruising, bleeding, difficulty
healing
• 5-year survival rate: varies greatly depending on
age/ when detected!
– 23.4%(adults with acute myelogenous leukemia) – 90.9%
(children under 5 with acute lymphocytic leukemia)
• Early detection: no effective screening, watch for
signs/symptoms
Primary Prevention of Cancer
Avoid the major risk factors!
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Tobacco use
Overweight/obesity
low fruit and vegetable intake
Physical inactivity
Alcohol use
Chronic HPV infection
Urban air pollution
5 gives you 50%
• The BC Cancer agency stresses that changing
just 5 main lifestyle behaviours reduces your
risk of cancer by approximately 50%!!!
– Smoking
– Physical inactivity
– Poor diet (fats, low fibre, high salt, high protein)
– Sunlight exposure
– Unhealthy weight