Transcript Understanding and Preventing Cancer

Cancer
Ray M. Merrill, PhD, MPH
Department of Health Science
Brigham Young University
Did you know?
In the United States…
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1 in 3 people will develop cancer in their lifetime
1 in 8 women will develop breast cancer in their
lifetime
1 in 6 men will develop prostate cancer in their
lifetime
Over 1,400,000 people will be diagnosed with
cancer this year
Over 550,000 people will die from cancer this
year
Percent (%) of Total Deaths
Fifteen Leading Causes of Death, US, 2004
Rank
Cause of Death
Death Rate*
Number of Deaths
1
Heart diseases
652,486
27.2
217.0
2
Cancer
553,888
23.1
185.8
3
Cerebrovascular diseases
150,074
6.3
50.0
4
Chronic lower respiratory diseases
121,987
5.1
41.1
5
Accidents (unintentional injuries)
112,012
4.7
37.7
6
Diabetes mellitus
73,138
3.1
24.5
7
Alzheimer disease
65,965
2.8
21.8
8
Influenza & pneumonia
59,664
2.5
19.8
9
Nephritis, nephrotic syndrome, & nephrosis
42,480
1.8
14.2
10
Septicemia
33,373
1.4
11.2
11
Intentional self-harm (suicide)
32,439
1.4
10.9
12
Chronic liver disease & cirrhosis
27,013
1.1
9.0
13
Hypertension & hypertensive renal disease
23,076
1.0
7.7
14
Parkinson disease
17,989
0.8
6.1
15
Assault (homocide)
17,357
0.7
5.9
All other & ill-defined causes
414,674
17.3
*Rates are per 100,000 population and age-adjusted to the 2000 US standard population.
Source: US Mortality Public Use Data Tape, 2004, National Center for Health Statistics, Centers for Disease Control and Prevention, 2006.
What is cancer?
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Cancer is a collective name that refers to
a group of many diseases with one
common characteristic: uncontrolled cell
growth or loss of the cell's ability to
perform apoptosis (cell suicide).
Mutations occur to genes that control the
normal process of cell growth and death
Gradual increase in the number of
uncontrolled dividing cells
Mass of tissue occurs called a “tumor”
(also called a neoplasm)
Development of Cancer from
genetically altered cell to
metastasis
Why do mutations happen?
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Some cancer-causing
mutations are simply
spontaneous errors that
appear in normal DNA
molecules when cells
duplicate their DNA prior to
cell division
Some are related to
environmental
factors/exposures, diet,
lifestyle choices or heredity
(a few “suseptibility genes”
Accumulation of mutations in
these 3 areas=cancer
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The mutations that contribute to the
development of cancer affect three general
classes of gene:
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Oncogenes
Tumor suppressor genes
DNA repair genes
Cancer Tends to Involve Multiple
Mutations
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The formation of cancer usually requires
multiple mutations, with the chance
increasing for mutations to accumulate
and cancer to develop with more years of
life (Doll & Peto, 1981).
Heredity and Cancer
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Cancer is not considered an
inherited illness since 80 to 90
percent occur in people with no
family history of the disease
E.g., only about 5 percent of
breast cancers are thought to
be due to inheritance of
particular form(s) of a "breast
cancer susceptibility gene."
Different Kinds of Cancer
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Carcinomas
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Sarcomas
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Arise from cells found in the supporting tissues of the body such as
bone, cartilage, fat, connective tissue, and muscle
Lymphomas
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Most common types of cancer
Arise from the cells that cover external and internal body surfaces
Lung, breast, prostate, and colon are the most frequent cancers of
this type in the United States
Arise in the lymph nodes and tissues of the body's immune system
Leukemias
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Cancers of the immature blood cells that grow in the bone marrow
and tend to accumulate in large numbers in the bloodstream
Tumor Grading/Staging
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Microscopic examination also provides
information regarding the likely behavior of a
tumor and its responsiveness to treatment.
A low number grade (grade I or II) refers to
cancers with fewer cell abnormalities than
those with higher numbers (grade III, IV).
Tumor Grading/Staging
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Based on the answers to the following
questions, the cancer is assigned a
"stage."
1. How large is the tumor, and how far has it
invaded into surrounding tissues?
 2. Have cancer cells spread to regional lymph
nodes?
 3. Has the cancer spread (metastasized) to
other regions of the body?
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Why Cancer Is Potentially
Dangerous
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A malignant tumor, a
"cancer," is a more
serious health
problem than a
benign tumor
because cancer cells
can spread to distant
parts of the body.
Cancer Detection and Diagnosis
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Early detection affects the outcome of the cancer
When cancer is found (type and how fast it is
growing)
Invasion
Metastasized
Early Cancer May Not Have Any
Symptoms
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Screening methods are designed to check
for cancer in people with no symptoms.
Some examples of screening methods
are:
Pap Test/smear
 Mammograms
 Blood Tests (PSA)
 Fecal Occult Blood Test (FOBT)
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Diagnose the presence of cancer
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Screening tests indicate the
possible existence of cancer,
a doctor must then perform a
biopsy
For leukemias, a small blood
sample serves the same
purpose
Microscopic examination will
tell the doctor whether a
tumor is actually present and,
if so, whether it is malignant
(i.e., cancer) or benign.
Tumor grade and stage are
related to cancer survival
What Causes Cancer?
Heredity? Behaviors? Other Factors?
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In theory, differences
in heredity or
environmental risk
factors might be
responsible for the
different cancer rates
observed in different
countries.
Tobacco Use and Cancer
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Cigarette smoking linked with cancer of the:
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lung
Mouth
Larynx
Esophagus
Stomach
Pancreas
Kidney
Bladder
Cervix
Current estimates suggest that smoking cigarettes is
responsible for at least one out of every three cancer
deaths.
Smoking-Related Cancers
Relative Risks
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Lip & Oropharangyeal
Oesophageal
Stomach
Anal
Pancreatic
Laryngeal
Lung
Cervix
Vulvar
Penile
Bladder
Renal Parenchymal
Renal Pelvic
Ex-smoker
1.76
1.79
1.11
1.83
1.15
2.86
6.75 M
5.07 W
1.31
1.37
1.6
1.7
1.61
1.95
Current Smoker
4.55
4.01
1.41
3.18
3.18
7.48
13.0 M
11.4 F
1.75
3.42
1.8
2.7
1.64
3.96
Source: Single et al., Am J Public Health 1999;89:385-390.
Low-Strength Radiation
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Some atoms give off radiation, which is
energy that travels through space.
Prolonged or repeated exposure to certain
types of radiation can cause cancer.
High-Strength Radiation
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X-rays or radiation emitted from
unstable atoms called
radioisotopes
Stronger than ultraviolet radiation
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Can penetrate through clothing and
skin and into the body
High-strength radiation can cause
cancers of internal body tissues
Examples of Human Cancer
Viruses
Viruses
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A few viruses also can trigger the
development of cancer
Cannot reproduce on their own
Viruses are small infectious agents
Enter into living cells and cause the
infected cell to produce more copies of the
virus
Causes the cell to become malignant
Bacteria and Stomach Cancer
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The bacterium H. pylori, which can cause
stomach ulcers, has been associated with the
development of stomach cancer
Breast cancer risk factors
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Most common cancer in women and second to lung
cancer in the number of cancer deaths among women
Causes/risk factors
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Heredity
Long-term exposure to high blood levels of estrogen
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Early onset of menstruation
Late onset of menopause
No children or first child after age 30
Obesity
Current use of HRT
Alcohol use
Inactivity
Diet low in vegetables and fiber
Prostate Cancer
Risk Factors
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Age
Race (African American=higher)
Diet: high in calories
Male Hormones
Environmental Exposures
A Vasectomy, BPH, STD’s
Family History of Prostate Cancer
Cancer Risk and Aging
Summary of What Causes Cancer
Source: CDC
Sexual Factors
Environmental &
Occupational
Factors
7%
Alcohol Overuse
3%
Tobacco Use
10%
30%
Other Factors
15%
Diet & Physical
Activity
35%
Ways to prevent cancer:
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Maintain a healthy weight;
Eat no more than two or three servings of red meat per week;
Take a multivitamin with folate every day;
Drink less than one alcoholic drink a day;
Eat five or more servings of fruits and vegetables per day;
Eat more high fiber foods such as whole grains, wheat cereals, bread, and
pasta;
Include cruciferous vegetables in your diet (such as broccoli, cabbage, etc.);
Do not smoke;
Protect yourself from the sun;
Avoid certain workplace exposures;
Protect yourself and your partner(s) from sexually transmitted infections; and
Exercise regularly.
Quick Quiz 3pts/ques
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1. What is the most common cancer for men,
women?
2. Give 3 risk factors for the most prevalent
male cancer
3. Give 3 risk factors for the most prevalent
female cancer
4. What is the common characteristic that
makes cells result in cancerous growth?
Quick Quiz cont.
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5. What are the four main categories/kinds of
cancer and describe what type of tissue that each
arises from.
6. Compare benign vs malignant
7.Using no more than 5 sentences, describe how
a genetically altered cell becomes cancer that has
spread throughout the body
8. Describe the I-IV grading/staging system for
cancer
Quick Quiz, cont
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9. How and to what extent does genetics play in
the development of cancer?
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10. List 3 ways cancers can be prevented