Download Cancer

Chapter
12
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What Is Cancer?
 Common Cancers
 The Causes of Cancer
 Detecting and Treating Cancer

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12-2

Cancer: Abnormal, uncontrolled
multiplication of cells, which, if left
untreated, can ultimately cause death
 Cancer is responsible for 1 out of every 4
deaths in the US each year, and it is the
second most common cause of death
after heart disease
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12-3

Tumor: A mass of tissue that serves no
physiological purpose; also called a
neoplasm
 Benign tumor: A tumor that is not cancerous
 Malignant tumor: A tumor that is
cancerous and capable of spreading
 Lymphatic system: A system of vessels
that returns proteins, lipids, and other
substances from fluid in the tissues to the
circulatory system
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
Malignant cell divides without regard for
normal control mechanisms
 Produces a mass of abnormal cells
 Eventually detected

A few cancers, like leukemia,
do not produce a mass
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12-5
SOURCE: American Cancer Society 2013 Cancer Facts and
Figures, 2013 Atlanta, GA: American Cancer Society
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12-6
SOURCE: American Cancer Society 2013 Cancer Facts and
Figures, 2013 Atlanta, Ga: American Cancer Society
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12-7

Metastasis: Spread of cancer cells
from one part of the body to another
 Occurs because cancer cells do not stick
to each other as strongly as normal
cells do and therefore may not remain
at the site of the original location
 To control the cancer, every
cancerous cell must be removed
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12-8

Lung cancer most common cause of
cancer death in the U.S.
 Responsible for about 159,000 deaths a year

Tobacco smoke accounts for 87% of lung
cancer deaths
 When combined with other carcinogens, risk
for smokers can increase 10 times or more
▪ Carcinogen: Any substance that causes cancer
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12-9

Symptoms include persistent cough,
chest pain, or recurring bronchitis
 Most often treated by combination of
surgery, radiation, and chemotherapy
 Chemotherapy: The treatment of cancer
with chemicals that destroy cancerous cells
 Only 15% of lung cancer patients are alive 5
years after diagnosis
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12-10

91% of cases are diagnosed in people
age 50 and older
 Many cancers arise from preexisting
polyps
 Many cases of colon cancers may be due
to inherited gene mutations
 Protective lifestyles can affect colon
cancer risk, including good nutrition,
physical activity, and not smoking
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12-11

Symptoms include changes in bowel
habits and bleeding from the rectum
 Tests can detect small amounts of blood
in the stool
 Rectal exam can detect some tumors, as
can a colonoscopy
 Exams should be performed yearly after
age 50
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12-12
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12-13

Breast cancer is
most common
cancer in
women and
is second
to lung cancer
in the number
of cancer deaths
among women
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12-14

Risk factors
 Strong genetic factor
 Other risk factors:
▪ Early first menstruation, or late-onset
menopause
▪ Having no children or having a first child after
age 30
▪ Hormone replacement therapy
▪ Being obese
▪ Using alcohol
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12-15

Risk factors
 Female hormone estrogen may be
common element in some risk factors
▪ Estrogen promotes cell growth in responsive
tissues, so increased estrogen exposure
may raise the risk of breast cancer
▪ Fat cells produce estrogen, and estrogen
levels are higher in obese women
▪ Alcohol increases estrogen in the blood
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12-16

Prevention
 Eat low-fat,
vegetable-rich diet
 Exercise regularly
 Limit alcohol intake
 Maintain a
healthy body weight
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12-17

Detection
 Mammogram: Low-dose X-ray of the
breasts used for early detection of breast
cancer
 Clinical breast exam
 Breast self-exams
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12-18

Detection
 Biopsy: Removal and examination
of small piece of body tissue
for purpose of diagnosis
 Ultrasonography: An imaging method
in which inaudible high-pitched sound
(ultrasound) is bounced off body structures
to create an image on a monitor
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
Treatment
 Lumps can be scanned by ultrasonography
and biopsied to check for malignancy
▪ If a lump is cancerous, several surgical treatments
may be used
▪ Chemotherapy or radiation treatment also used
 Several drugs developed for
preventing and treating breast cancer
 If discovered early, patients have about
98% chance of surviving more than 5 years
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12-20

Prostate cancer is most common
cancer in men and second leading
cause of cancer death in men
 Age is the strongest predictor with 97%
of cases occurring in men over age 50
 Prostate-specific antigen (PSA)
blood test: Diagnostic test for prostate
cancer that measures blood levels of PSA
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12-21

Treatment is usually removal of the
prostate, but radiation may be used
 5-year survival rate is now nearly 100%
 Small slow-growing tumors in older men
may be treated with watchful waiting
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12-22

Cervical cancer
 Most cases stem from infection by HPV
 Pap test: Scraping of cells from cervix
for examination to detect cancer
▪ Abnormal cells removed surgically or
by destroying them with ultracold
probe or localized laser treatment
 Two HPV vaccines approved by the FDA
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12-23

Uterine or Endometrial cancer
 Cancer of the lining of the uterus
most often occurs after age 55
 Usually detectable by pelvic examination
 Uterine cancer treated surgically by
removing the uterus
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12-24

Ovarian cancer
 Ovarian cancer rare compared with uterine
cancer, but it causes more deaths
▪ Often diagnosed late in its development
 Lowering woman’s lifetime number of
ovulation cycles reduces risk
▪ Symptoms: bloating, pelvic or abdominal
pain, difficulty eating or feeling
full quickly, urinary problems
▪ Treated by surgical removal of
ovaries, fallopian tubes, and uterus
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12-25

Skin cancer most common cancer
 Linked to exposure to UV radiation from the
sun
 Melanoma: A malignant tumor of the skin
that arises from pigmented cells, usually a
mole
 Ultraviolet (UV) radiation: Light rays
of a specific wavelength, emitted by
the sun; most UV rays are blocked by
the ozone layer in the upper atmosphere
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12-26

Basal cell carcinomas and squamous
cell carcinomas are 95% of skin cancers
 Basal cell carcinoma:
Cancer of deepest
layers of the skin
 Squamous cell
carcinoma: Cancer
of the surface layers
of the skin
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12-27

Melanoma most dangerous skin
cancer because it spreads rapidly
 Usually occurs at site of mole, which
becomes enlarged, mottled, and
irregular in surface or borders
 Melanomas most common on the
back, chest, abdomen, and lower legs
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12-28
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12-29

Cancers of the oral cavity,
pharynx, larynx, and nasal cavity
 Trace to cigarette, cigar, or pipe
smoking, the use of spit tobacco,
and excessive consumption of alcohol
 Head and neck cancers twice as great in
men and most frequently in men over 40
 Chemotherapy, radiation, or surgery
used to treat head and neck cancers
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12-30

Testicular cancer is most common
cancer among men ages 20 to 35,
but it is rare
 Regular self-examination
 Tumors treated by surgical removal
and, if the tumor has spread, by
chemotherapy
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12-31

Pancreatic cancer kills 38,000
Americans annually
 Usually well advanced when detected
 There is no effective cure available

Bladder cancer
 Men 4 times more likely to have it
 Smoking is key risk factor
 Symptoms: blood in the urine, increased
frequency of urination
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12-32

Kidney cancer usually occurs over 50
 Smoking, obesity, and family history are
mild risk factors
▪ Symptoms: fatigue, pain in the side, and blood
in the urine

Brain cancer can arise from most cell
types found in the brain
 Ionizing radiation a risk factor
 Some brain tumors curable
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12-33

Leukemia is cancer of white blood cells
 Starts in bone marrow but can spread to
other organs and the central nervous
system

Lymphoma is a form of cancer that
begins in the lymph nodes
 May spread to almost any part of the body
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
DNA basics
 Chromosomes: Threadlike bodies
in a cell nucleus that contain
molecules of DNA; most human cells
contain 23 pairs of chromosomes
▪ DNA: Deoxyronucleic acid, a chemical
substance that carries genetic information
▪ Gene: A section of a chromosome that
contains the instructions for making a
particular protein; the basic unit of heredity
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12-35

DNA mutations and cancer
 Mutation is any change in makeup of a gene
▪ Some mutations inherited
▪ Others caused by environmental agents
 Oncogene: A gene involved in the
transformation of a normal cell into a
cancer cell
 Cancer Promoters
▪ Some substances accelerate growth of cells,
which means less time for a cell to repair DNA
damage caused by other factors
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12-36

Smoking responsible for up to
90% of lung cancers and for
about 30% of all cancer deaths
 Tobacco use responsible for nearly
one in five American deaths each year
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12-37

Dietary fat and meat
 Diets high in fats and meat may contribute
to colon, prostate, and stomach cancer
 Omega-6 polyunsaturated fats associated
with a higher risk of certain cancers

Alcohol
 Associated with several cancers
 Alcohol and tobacco interact as risk factors
for oral cancer
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12-38

Fried food
 High levels of acrylamide found
in starch-based foods that is fried
or baked at high temperatures
▪ Acrylamide is also found in tobacco

Fiber
 Experts recommend a high-fiber diet
for its overall positive effect on health
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12-39

Fruits and vegetables
 Researchers identified mechanisms by which
food components may act against cancer
▪ Carotenoid: yellow-to-red plant pigments
that can be converted to vitamin A by
the liver; many act as antioxidants
or have other anti-cancer effects
▪ Phytochemical: Naturally occurring
substance found in plant foods
that may help prevent chronic
diseases such as cancer and heart disease
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12-41
The ACS recommends
maintaining a healthy weight
throughout life by balancing
caloric intake with physical
activity
 The ACS also recommends
achieving and maintaining a
healthy weight if you are
currently overweight or
obese

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12-42

Ingested chemicals
 Some food additives potentially
dangerous including the nitrates
and nitrites found in processed meats

Environmental and industrial pollution
 Less than 2% of cancer deaths caused
by general environmental pollution
 Exposure to carcinogenic materials in
workplace is a more serious problem
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12-43

Radiation
 All sources of radiation are potentially
carcinogenic
 Successful efforts made to reduce radiation
needed for necessary medical X-rays

Microbes
 About 15 to 20% of world’s cancers caused
by microbes
▪ HPV
▪ Epstein-Barr virus
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12-44
SOURCE: Calle, E E, et al 2003 Overweight, obesity, and:
mortality from cancer in a prospectively studied cohort of US
adults New England Journal of Medicine 348(17): 1625–1638
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12-45

Detecting cancer
 Self-monitoring
▪ Be aware of risk factors
▪ Report changes to a physician

Treating cancer
 Surgery
 For most cancers, surgery most useful
treatment
 Chemotherapy
 Radiation
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12-46