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PowerLecture:
Chapter 23
Genes and
Disease: Cancer
Learning Objectives





Understand the relationship between cancer
and cellular genetic controls.
Know the steps in cancer development.
List the environmental factors that influence
cancer development.
Describe the relationship between lifestyle
and cancer.
Describe some of the characteristics of
more well-known cancers.
Impacts/Issues
Between You
and Eternity
Between You and Eternity
Cancer affects one in three people in the
U.S. and kills one in four; each year more
than 200,000 women are diagnosed with
breast cancer alone.




Some women carry the BRCA1 or BRCA2
gene, which increases the risk of developing
breast cancer.
Some women with elevated risk for breast
cancer opt for preventive mastectomy.
Diagnosed early, most cancers are
treatable, and many curable.
Video: Preventing Cancer Surgically
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2003,
Volume VII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Impacts/Issues
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 Genome
News Network: Breast Cancer
Susceptibility Genes: Overstating the Risk?
 InfoTrac: Monster Tumors Show Scientific
Potential in War against Cancer. Elizabeth
Svoboda. The New York Times, June 6,
2006.
How Would You Vote?
To conduct an instant in-class survey using a classroom response
system, access “JoinIn Clicker Content” from the PowerLecture main
menu.
 Would
you support legislation requiring
insurers to pay for the removal of a breast
that is only at risk for developing cancer?


a. Yes, they should be required to pay at least in
proportion to a woman's chances for developing
cancer.
b. No, they should pay for annual exams, but not
for surgery unless cancer is actually detected.
Useful References for
How Would You Vote?
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.

InfoTrac: Breast Removal: The Latest in Cancer
Prevention. HealthFacts, Feb. 1999.
 InfoTrac: Is a 0.2% Chance of Death from Breast
Cancer Worth a Bilateral Prophylactic Mastectomy?
Contemporary OB/GYN, June 2005.
 American Cancer Society: Insurance May Not
Cover Preventive Surgery for High-Risk Women
Section 1
Cancer: Cell
Controls Go Awry
Cancer: Cell Controls Go Awry
Some tumors are cancer, others are not.


Overgrowth of cells in a tissue (hyperplasia)
results in the formation of a defined mass called
a tumor, or neoplasm.
Figure 23.2
Cancer: Cell Controls Go Awry

Benign tumors are often enclosed in a capsule
of connective tissue.
•
•
•
The cells are organized in orderly array.
The cells grow slowly and are well differentiated.
Because they do not affect surrounding tissue (there
are exceptions), they usually are not considered a
threat to health.
capsule
© 2007 Thomson Higher Education
Fig 23.1, p.428
Cancer: Cell Controls Go Awry

Dysplasia is an abnormal change in the sizes,
shapes, and organization of cells in a tissue.
•
•
•
It is often a precursor to cancer.
Microscopically, the edges of the tumor look ragged
and the cells are clumped.
Functionally the cells have many characteristics that
alter their behavior from that of normal cells.
Cancer: Cell Controls Go Awry
Cancer cells have abnormal structure.



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A cancer cell has a large nucleus, less
cytoplasm, and is poorly differentiated.
The cytoskeleton shrinks and becomes
disorganized; proteins of the plasma membrane
also become altered.
Cellular division of transformed cells results in
cancerous daughter cells.
Cancer: Cell Controls Go Awry
Cancer cells lack normal controls over cell
division.



In a cancerous tumor, more cells are dividing
than dying, so growth continues unaffected by
the usual contact inhibition provided by
crowding.
Cancer cells lack strong cell-to-cell junctions
and so tend to move about (metastasis) and
become malignant.
a
Cancer cells break away
from their home tissue.
b
The metastasizing cells become
attached to the wall of a blood vessel or
lymph vessel. They secrete digestive
enzymes into it. Then they cross the
wall at the breach.
c
Cancer cells creep or tumble along
inside blood vessels, then leave the
bloodstream the same way they got in.
They start new tumors in new tissues.
Fig 23.3, p.429
Cancer: Cell Controls Go Awry

Some cancer cells produce HCG (human
chorionic gonadotropin), which can be detected
in blood and which signals cancer somewhere
in the body; cancer cells also produce
angiogenin, which encourages new blood
vessel development.
Animation: Cancer and Metastasis
CLICK
TO PLAY
Animation: Characteristics of Cancer
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TO PLAY
Video: Fibroid Tumors
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2004,
Volume VIII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Section 1
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac:
Gene Signature Helps Predict
Melanoma Outcome. Diana Mahoney.
Internal Medicine News, Mar. 1, 2006.
Section 2
The Genetic Triggers
for Cancer
The Genetic Triggers for Cancer
Cancer develops in a multistep process.


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The transformation of a normal cell into a
cancerous one is called carcinogenesis.
Cancer develops through a series of changes
that upset normal controls over cell division.
Oncogenes induce cancer when tumor
suppressor genes are mutated.


Proto-oncogenes are normal genes that
regulate cell growth and development.
POSSIBLE TRIGGERS
chemical
carcinogens
virus
normal cell
radiation
heredity
mutation in proto-oncogenes and
tumor suppressor genes remove
normal growth controls
abnormal
cell
immune system breakdown
immune system activated
(cytotoxic T cells and NK cells)
abnormal cell proliferates
abnormal cell destroyed
tumor
tumor cells break away;
metastasis to other parts of body
© 2007 Thomson Higher Education
Fig 23.4, p.430
POSSIBLE TRIGGERS
chemical
carcinogens
virus
normal cell
radiation
heredity
mutation in proto-oncogenes and
tumor suppressor genes remove
normal growth controls
abnormal
cell
immune system breakdown
immune system activated
(cytotoxic T cells and NK cells)
abnormal cell proliferates
abnormal cell destroyed
tumor
tumor cells break away;
metastasis to other parts of body
Stepped Art
Fig 23.4, p.430
The Genetic Triggers for Cancer

Oncogenes are modified from protooncogenes; they code for altered proteins that
remove the controls over cellular division.
•
•
•
Cancer cannot be caused by oncogenes alone but
requires the absence or mutation of tumor
suppressor genes.
For example, retinoblastoma is normally
suppressed by at least one gene, but if this gene is
altered, the suppression is removed and cancer
develops.
BRCA1 and BRCA2 are also tumor suppressor
genes whose disruption can lead to breast cancer.
BRCA 2
BRCA 1
Chromosome 13
Chromosome 17
Fig 23.5, p.431
The Genetic Triggers for Cancer


The p53 gene codes for a regulatory protein
that turns on proto-oncogenes that stop cell
division at the right time; its alteration removes
this inhibition and allows cells to divide
unchecked.
An oncogene may mutate in a way that triggers
expression.
•
•
Translocation may move an oncogene away from a
regulatory nucleotide sequence that normally
prevents its expression.
New genetic material may be introduced into a cell
(as by a virus) and disrupt controls.
The Genetic Triggers for Cancer
There also are other routes to cancer.


Inherited susceptibility to cancer.
•
•

If a mutation occurs in a germ cell and it removes
controls over a proto-oncogene, the defect can be
passed on to offspring.
Most instances of inherited cancer susceptibility are
complicated by the fact that several genes are
probably involved.
Viruses.
•
•
Viruses can become inserted into host cell DNA,
possibly altering the functioning of proto-oncogenes.
Viruses can also carry oncogenes and insert them
into host cell DNA.
The Genetic Triggers for Cancer

Chemical carcinogens.
•
•
•
•
Carcinogens are chemicals that can damage DNA,
resulting in subsequent mutations.
Some of the chemicals that cause cancer are byproducts of an industrialized society, such as
asbestos, vinyl chloride, and benzene; hydrocarbons
in cigarette smoke and fireplace soot; and
substances in dyes and pesticides.
Natural carcinogens include aflatoxin, produced by
a fungus that grows on peanuts.
Some chemicals may be “pre-carcinogens” that
cause changes only after they have been altered by
metabolic activity of the cell.
The Genetic Triggers for Cancer

Radiation.
•
•

Radiation can damage DNA.
Sources include UV radiation from sunlight and
tanning lamps, X rays, cosmic rays, radon gas, and
nuclear reactors; sun exposure is probably the
greatest risk factor.
Breakdowns in immunity.
•
•
•
A healthy immune system regularly detects and
destroys cancer cells by means of cytotoxic T cells.
The protective function of the immune system can be
compromised by therapeutic drugs or even anxiety
and severe depression.
Sometimes, the cancer itself can suppress the
immune system.
Useful References for Section 2
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 Cancer
Backup: Retinoblastoma in Children
 InfoTrac: Study IDs Gene Triggers to Liver
Cancer. Jamie Talan. Newsday (Melville, NY),
June 28, 2006.
 InfoTrac: Scientists Link Gene to Metastatic
Cancer. UPI NewsTrack, July 3, 2006.
Section 3
Assessing the Cancer Risk
from Environmental
Chemicals
Assessing the Cancer Risk from
Environmental Chemicals
According to the American Cancer Society,
factors in the environment account for half
of all cancers; these factors include UV
light, radiation, and industrial and
agricultural chemicals.


Roughly 40% of the food
in supermarkets in the
U.S. contains pesticide
residues; some of these
pesticides are banned in
the U.S., but come in on imports.
Figure 23.6
Assessing the Cancer Risk from
Environmental Chemicals


More exposure comes from pesticides used in
community and home spraying.
The Ames test,
developed by
biochemist Bruce
Ames, uses bacteria
to test for the
mutagenic potential
of various chemicals.
Useful References for Section 3
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac:
Science That Sticks: Chemist’s
Work behind U.S. Decision to Ban PFOA.
Canadian Chemical News, Mar. 2006.
 EPA: Carcinogens
Section 4
Diagnosing Cancer
Diagnosing Cancer

Early and accurate diagnosis of cancer is
important for maximizing the success of
treatment.
Figure 23.7
Diagnosing Cancer
 There
are seven general warning signs of
cancer (CAUTION):
Diagnosing Cancer
Various tests can be performed to confirm
or rule out cancer.



Blood tests can detect tumor markers, such as
HCG or PSA (prostate-specific antigen).
Radioactively labeled monoclonal antibodies
are useful in pinpointing the location and size of
certain tumors; medical imaging techniques
such as MRI, X rays, ultrasound, and CT are
also used to locate tumors.
Diagnosing Cancer


The definitive detection tool is biopsy, removal
of a small piece of tissue for microscopic
examination.
A snippet of radioactively labeled DNA, called a
DNA probe, can be used to locate gene
mutations; however, it is expensive and usually
not covered by insurance.
Recommended Cancer Screening Tests
Useful References for Section 4
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 Oncology
Nursing Society: Cancer
Symptoms
 Mayo Clinic: Diagnosing Cancer
 InfoTrac: Early Cancer Diagnosis: Present
and Future. Andre Baron et al. Patient Care
for the Nurse Practitioner, Sept. 2005.
Section 5
Some Major Types
of Cancer
Some Major Types of Cancer
Cancers are named according to the type of
tissue where they are first formed.


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Sarcomas are cancers of connective tissues.
Carcinomas arise from epithelium, including
skin and epithelial linings of internal organs.
Cancers of glands are adenocarcinomas.
Lymphomas are cancers of lymph tissue.
Cancer of stem cells or bone marrow is
leukemia.
Some Major Types of Cancer
The following conclusions are drawn from
the cancer statistics in Figure 23.8.



Highest cancer incidence: male—prostate;
female—breast.
Highest cancer deaths: both male and female—
lung.
Cancer Incidence by Site and Sex*
MALE
Cancer Deaths by Site and Sex
FEMALE
MALE
FEMALE
prostate
232,090
breast
211,240
lung and
bronchus
93,010
lung and
bronchus
90,490
lung and
bronchus
73,020
lung and
bronchus
79,560
prostate
30,350
colon and
rectum
71,820
colon and
rectum
73,470
colon and
rectum
28,540
colon and
rectum
27,750
urinary bladder
47,010
uterus
40,880
ovary
16,210
melanoma of
the skin
33,580
non-Hodgkin
lymphoma
27,320
pancreas
15,820
leukemia
12,540
non-Hodgkin
lymphoma
29,070
melanoma of
the skin
26,000
kidney
22,490
ovary
22,220
leukemia
19,640
thyroid
19,190
oral cavity
19,100
urinary bladder
16,080
pancreas
16,080
pancreas
16,100
all sites
710,040
all sites
662,870
esophagus
10,530
liver
10,330
non-Hodgkin
lymphoma
10,150
breast
40,410
pancreas
15,980
leukemia
10,070
non-Hodgkin
lymphoma
9,050
uterus
7,310
urinary bladder
8,970
multiple myeloma
5,640
kidney
8,020
brain
5,480
all sites
295,280
all sites
275,000
* Excludes basal- and squamous-cell skin cancer and in situ carcinomas except urinary bladder.
© 2007 Thomson Higher Education
Fig 23.8, p.434
Video: Fighting Sarcoma
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2004,
Volume VIII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Section 5
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac:
Sarcomas Most Common Cancer
Type in Teenagers. GP, April 7, 2006.
 InfoTrac: Mutations Point the Way to New
Leukemia Drugs. Ascribe Higher Education
News Service, July 17, 2006.
 Abramson Cancer Center: Oncolink
 Association of Cancer Online Resources:
Types of Cancer
Section 6
Treating and
Preventing Cancer
Treating and Preventing Cancer
Chemotherapy and radiation kill cancer
cells directly.


Chemotherapy uses drugs to kill cancer cells.
•
•
The cancer drugs disrupt DNA replication during S
phase or prevent mitosis by inhibiting the formation
of the mitotic spindle.
These drugs are also toxic to rapidly growing human
cells, such as hair cells, stem cells, and epithelial
cells.
Treating and Preventing Cancer




Radiation kills both cancer cells and the healthy
cells around them.
Adjuvant therapy combines less-toxic
chemotherapy with surgery to remove the
tumor.
Monoclonal antibodies are used to deliver lethal
doses of radiation or anticancer drugs to tumor
cells specifically.
Immunotherapy is the use of substances such
as interferon and interleukins to activate
cytotoxic T cells to attack the cancer.
Treating and Preventing Cancer
Anticancer drugs may be matched to
genetic characteristics of cancer cells.



Traditional chemotherapy drugs were matched
to the organ where the cancer occurs.
New strategies aim to match therapy with the
specific genetic characteristics of the cancerous
cells, regardless of where the cancer occurs.
Treating and Preventing Cancer
You can limit your cancer risk.



We cannot control heredity of some aspects of
biology, but we can make choices to affect our
own health.
Some strategies for limiting cancer include:
•
•
•
•
•
•
Avoid tobacco in any form.
Maintain desirable weight.
Eat a low-fat, high-fiber diet.
Restrict alcohol intake.
Avoid hazardous chemicals
in the workplace.
Avoid excessive sun exposure.
Figure 23.9
Video: Prostate Cancer Prevention
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2004,
Volume VIII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Section 6
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 National
Cancer Institute: Clinical Trials
 Cancer Research Institute
 InfoTrac: HPV DNA Testing and HPV
Vaccines Described by Experts as
Combination That Offers Best Hope of
Preventing Cervical Cancer. PR Newswire,
April 27, 2006.
Section 7
Cancers of the Breast
and Reproductive
System
Cancers of the Breast and
Reproductive System
Breast cancer is a major cause of death.


Breast cancer ranks second to lung cancer as a
cause of death in females.
•
•

Causative factors include obesity, late childbearing,
early puberty, late menopause, excessive estrogen,
and familial history.
Early detection by breast examination and
mammography are keys to cure.
Treatment methods include modified radical
mastectomy and lumpectomy; some drugs
such as tamoxifen are also used.
1. Lie down and put a folded towel under your left
shoulder,then put your left hand behind your head. With
the right hand (fingers flat), begin the examination of your
left breast by following the outer circle of arrows shown.
Gently press the fingers in small, circular motions to
check for any lump, hard knot, or thickening. Next, follow
the inner circle of arrows. Continue doing this for at least
three more circles, one of which should include the nipple.
Then repeat the procedure for the right breast. For a
complete examination, repeat the procedure while
standing in a shower. Hands glide more easily over wet
skin.
2. Stand before a mirror, lift your arms over your head,
and look for any unusual changes in the contour of your
breasts, such as a swelling, dimpling, or retraction
(inward sinking) of the nipple.Also check for any unusual
discharge from the nipple.
If you discover a lump or any other change
during a breast self-examination, it’s
important to see a physician at once. Most
changes are not cancerous, but let the
doctor make the diagnosis.
Fig 23.10b, p 436
Cancers of the Breast and
Reproductive System
Uterine and ovarian cancer affect women.



Uterine cancer rates are declining due to early
detection, mainly by Pap smear.
Ovarian cancer is often lethal because
symptoms do not occur until the cancer is
advanced; the chemical taxol has been used
with moderate success.
Cancers of the Breast and
Reproductive System
Testicular and prostate cancer
affect men.



Testicular cancer is painless in
its early stages but may spread
to the lymph nodes and
eventually to the lungs; surgery
is the usual treatment.
Prostate cancer is second only
to lung cancer in causing cancer
deaths in men; a PSA blood test
is diagnostic, and cure rate is
high for cancers detected early.
Figure 23.11
Video: Breast Cancer Treatment
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2003,
Volume VII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Section 7
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac:
Tylenol Lowers Ovarian Cancer
Risk. UPI NewsTrack, July 10, 2006.
Section 8
A Survey of Other
Common Cancers
A Survey of Other Common Cancers

Oral cancers occur in the lips, mouth,
tongue, salivary glands, and throat and are
most common among users of any form of
tobacco; most of the cancers are highly
deadly.
A Survey of Other Common Cancers
Lung cancer kills more people than any
other cancer.



The overwhelming risk factor is smoking, a
practice that is declining in men but increasing
in women.
Lung cancers include squamous cell
carcinomas, adenocarcinomas (large-cell
carcinomas), and small-cell carcinomas.
A Survey of Other Common Cancers

Cancers of the stomach and pancreas are
usually adenocarcinomas of the duct cells
and are usually not detected until they have
spread.
A Survey of Other Common Cancers
Most cancers of the colon and rectum
(colorectal cancers) are
adenocarcinomas.



The cancers generally start
as small polyps (growths).
Warning signs include blood
in the feces; a family history
of colorectal cancer or
inflammatory bowel disease
is a major risk factor.
Figure 23.12
A Survey of Other Common Cancers
Urinary system cancers.



Carcinomas of the kidneys and bladder are
related to smoking and industrial chemicals.
Wilms tumor is an inherited type of kidney
cancer that appears most often in children.
A Survey of Other Common Cancers
Cancers of the blood and lymphatic system.



Lymphomas, such as non-Hodgkin
lymphoma, Hodgkin’s disease, and Burkitt
lymphoma, seem to increase with infections
that impair the immune system.
Leukemias—cancers of the stem cells of the
bone marrow—lead to overproduction of white
blood cells; treatment is with chemotherapy,
especially the plant derivatives vincristine and
vinblastine.
A Survey of Other Common Cancers
Skin cancers are the most common of all
cancers.




Malignant melanoma, cancer of the
melanocyte cells, metastasizes aggressively.
Squamous cell carcinomas start out as scaly,
reddened bumps that grow rapidly and can
spread to adjacent lymph nodes.
Basal cell carcinomas grow slowly into ulcers
with beaded margins.
A Survey of Other Common Cancers

Basal cell carcinoma and squamous cell
carcinoma are more common than malignant
melanoma and can be easily treated with minor
surgery.
Video: Skin Sun Damage
 This
video clip is available in CNN Today
Videos for Biology, 2003, Volume VII.
Instructors, contact your local sales
representative to order this volume, while
supplies last.
Video: Custom Cancer Vaccine
 This
video clip is available in CNN Today
Videos for Anatomy and Physiology, 2003,
Volume VII. Instructors, contact your local
sales representative to order this volume,
while supplies last.
Useful References for Section 8
The latest references for topics covered in this section can be found at
the book companion website. Log in to the book’s e-resources page at
www.thomsonedu.com to access InfoTrac articles.
 InfoTrac: American Academy
of Dermatology
Warns of Skin Cancer Risks This Summer;
More Than 1 Million New Cases of Skin
Cancer to Be Diagnosed This Year in U.S.
Internet Wire, July 7, 2006.
 Mayo Clinic: Pancreatic Cancer
 American Cancer Society: All About Colon
and Rectum Cancer