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Title: Cancer: Uncontrolled Cell Division and Differentiation


1
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18
  • Cancer Uncontrolled Cell Division and
    Differentiation

2
Cancer An Introduction
  • 100 different types of cancer
  • All cancers are diseases of cell division and
    differentiation
  • Normal Cells
  • Have regulatory mechanisms that maintain an
    appropriate rate of cell division
  • Internal clock
  • Hormones
  • Inhibitory signals from nearby cells
  • Remain in one location throughout their lifespan

3
Tumors Can Be Benign or Cancerous
  • Hyperplasia
  • Substantial increase in the rate of cell division
  • Tumor
  • Also known as a neoplasm
  • A discrete mass of cells resulting from
    hyperplasia
  • Benign tumors
  • Noncancerous
  • Remain in one location
  • Single, well-defined mass
  • May be surrounded by connective tissue
  • Often can be readily removed surgically

4
Figure 18.1
Benign tumor
Genetically alteredepithelial cell
Hyperplasia
Basement membrane
5
Cancerous Cells Lose Control Over Their Functions
and Structures
  • Dysplasia
  • Abnormal change in cell structure
  • Considered a precancerous state
  • Cancerous tumors
  • Abnormal cell structure
  • Loss of regulation of cell growth
  • In situ cancer
  • Tumor stays in one place

6
Cancerous Cells Lose Control Over Their Functions
and Structures
  • Malignant tumor
  • Tumor invades normal tissue and compromises organ
    function
  • Tumor may undergo metastasis
  • Spread of the cancer to another organ or body
    region
  • Secondary, malignant tumors at other locations
    may develop

7
Figure 18.2
Malignant tumor (cancer)
In situ cancer
Dysplasia
Hyperplasia
Geneticallyalteredepithelialcell
  • Cell dividesmore rapidlythan normal
  • Cells changeform
  • Cells stay inone place
  • Cancer cells invade surrounding tissueand enter
    blood and lymph
  • Metastases may form at distant sites

Metastases
Normal underlying connectiveor muscle tissue
Blood vessel
Invasion
Direction of flow
8
Table 18.1
9
How Cancer Develops
  • Two things must happen simultaneously for cancer
    to develop
  • 1. Cell must divide uncontrollably
  • 2. Cell must undergo physical changes and break
    away from surrounding cells
  • These changes usually correlate with specific
    mutations in the cells genes

10
Mutant Forms of Proto-Oncogens, Tumor Suppressor
Genes, and Mutator Genes Contribute to Cancer
  • Proto-oncogenes
  • Normal regulatory genes that promote cell growth
    and differentiation, division, or adhesion
  • Oncogenes
  • Mutated or damaged proto-oncogenes
  • May cause cells to grow and divide more quickly
    than normal
  • May result in a cell failing to respond to
    inhibitory signals
  • Cancer develops only when multiple oncogenes are
    present

11
Mutant Forms of Proto-Oncogens, Tumor Suppressor
Genes, and Mutator Genes Contribute to Cancer
  • Tumor suppressor genes
  • Regulatory genes repress cell growth, division,
    differentiation, and adhesion
  • May be turned off, damaged, or mutated in cancers
  • Example If the p53 tumor suppressor gene is
    mutated, a variety of cancers will develop more
    readily
  • p53 mutations have been found in cervical, colon,
    lung, skin, bladder, and breast tumors
  • Mutator genes
  • Involved in DNA repair during replication
  • May be mutated themselves and not function

12
Animation Cancer Right-click and select Play
13
A Variety of Factors Can Lead to Cancer
  • Age single most important factor in development
    of cancer
  • The longer we live, the more likely we are to die
    of cancer
  • Some genes may be inherited that increase
    susceptibility to cancer
  • Multigene basis of cancer
  • Carcinogenesis process of transforming a normal
    cell into a cancer cell
  • Carcinogen any substance or physical factor that
    causes cancer

14
A Variety of Factors Can Lead to Cancer
  • Viruses and bacteria (?15 of all cancers)
  • Human papillomavirus (HPV) cervical cancer
  • Hepatitis B and C viruses liver cancer
  • HIV Kaposis sarcoma
  • Epstein-Barr virus Hodgkins disease
  • Chemicals in the environment
  • Asbestos, benzene, some pesticides, dyes
  • Tobacco
  • Responsible for 30 of all cancer deaths
  • Radiation
  • Ultraviolet radiation (sun exposure) skin cancer
  • Causes ?80 of all skin cancers

15
A Variety of Factors Can Lead to Cancer
  • Diet and obesity
  • Likely involved in approximately 30 of cancers
  • Red meat, saturated animal fat increased risk of
    cancer of colon, rectum, prostate
  • Alcohol consumption increased risk of breast,
    rectal, colon, and liver cancer
  • High salt consumption associated with stomach
    cancer
  • Aflatoxin present in raw peanut butter
  • Type II diabetics have a much higher risk of
    dying of cancer

16
A Variety of Factors Can Lead to Cancer
  • Internal factors
  • Free radicals produced by metabolism may damage
    DNA
  • Antioxidants (vitamins A,C,E) may neutralize free
    radicals
  • Antioxidant containing foods blueberries,
    spinach, tomatoes

17
The Immune System Plays an Important Role in
Cancer Prevention
  • Immune system normally defends the body against
    cancers
  • Cancer cells may not be recognized as self and
    may be destroyed by the immune system
  • Anything that suppresses the immune system may
    make an individual more susceptible to cancer

18
Figure 18.6
Environmental factors
Abnormal cell destroyed
Immune systemresponsive
Normal cell
Abnormal cell
Mutations ofregulatorygenes andgenes
involvedin DNA repair.
Immune systemsuppressed
Internal factors
Inheritance
Tumor
Invasion
19
Advances in Diagnosis Enable Early Detection
  • Tumor imaging
  • X-rays
  • Example mammogram
  • Positron emission tomography (PET)
  • Magnetic resonance imaging (MRI)
  • Genetic testing
  • Identify mutated genes
  • Privacy and treatment issues
  • Enzyme tests for cancer markers
  • Screening large numbers of people

20
Figure 18.8
An X-ray. This is a color-enhanced X-ray of a
breastwith a tumor.
An ultrasound scan. This one shows a
prostatetumor (purple).
A PET scan of the brain.The yellow/red area is
atumor.
An MRI. This is an MRI of a brain, showing a
brain tumor(magenta and red area to the right).
21
Cancer Treatments
  • Conventional treatments
  • Surgery has improved with better imaging
    techniques
  • Radiation targets the tumor, but sometimes
    damages healthy cells
  • Chemotherapy use of cytotoxic drugs to destroy
    cancer cells
  • Side effects nausea, hair loss, anemia
  • Often kills normal cells as well
  • Often a combination of two or more of the above
    treatments is used

22
Cancer Treatments
  • Magnetism
  • Magnet is placed at the tumor
  • Tiny magnetic beads coated with chemotherapy
    drugs are injected and pulled to the tumor
  • Photodynamic therapy
  • Uses light-sensitive drugs that are taken up by
    cancer cells and lasers, which activate the
    toxicity of the drug

23
Cancer Treatments
  • Immunotherapy
  • Boosts the immune response of patient
  • Development of antibodies that specifically
    recognize cancer cells
  • Tagging antibodies with radioactive molecules or
    chemotherapeutic drugs
  • Development of vaccines against specific cancers
  • Starving cancers
  • Anti-angiogenic drugs prevent the development of
    a good blood supply to the tumor
  • Molecular treatments
  • Target oncogenes

24
Common Cancers Lung Cancer
  • Smoking leading risk factor
  • No simple screening test, so the cancer is often
    more advanced when detected
  • Early symptoms are nonspecific
  • Persistent coughing
  • Bronchitis
  • Recurrent pneumonia
  • Voice change
  • Treatment
  • Surgery, often combined with radiation and
    chemotherapy

25
Common Cancers Colon and Rectal Cancers
  • Symptoms
  • Blood in stool, rectal bleeding
  • Risk factors
  • Sedentary lifestyle, obesity, smoking, family
    history, low-fiber diet, high-fat diet
  • Start as polyps (benign tumors), which gradually
    become malignant
  • Screening tests can detect cancer early
  • Detection of blood in stool specimens
  • Colonoscopy examining interior of colon with
    flexible fiber-optic scope
  • Treatment polyp removal, tumor removal

26
Figure 18.10
Polyp
Intestinalfolds
Colonoscope
27
Common Cancers Breast Cancer
  • Early detection is crucial for survival
  • Mammogram low dose X-ray used for early
    detection
  • Detection of a lump on breast exam
  • Risk factors
  • Genetics two different genes increase risk
  • BRCA1 and BRCA2
  • Age
  • Early onset of menstruation, late menopause
  • Obesity after menopause
  • Oral contraceptives
  • Hormone replacement after menopause

28
Common Cancers Prostate Cancer
  • Most common after age 50
  • Biggest risk factor advancing age
  • Symptoms
  • Urination difficulties, blood in urine, pain in
    pelvic area
  • Diagnosis
  • Digital rectal exam
  • Blood test for PSA (prostate-specific antigen)
  • Biopsy
  • Treatment
  • Surgery, radiation therapy, hormones

29
Common Cancers Leukemia
  • Cancer of immature white blood cells in the bone
    marrow
  • Risk factors Down syndrome, exposure to ionizing
    radiation, benzene, infection with HTLV-1 virus
  • Childhood forms of leukemia as well as adult
    forms of leukemia
  • Symptoms nonspecific
  • Diagnosis blood tests and bone marrow biopsies
  • Treatment chemotherapy, or chemotherapy plus
    bone marrow transplant

30
Common Cancers Lymphoma
  • Cancer of lymphoid tissue
  • Includes Hodgkins and non-Hodgkins lymphoma
  • Symptoms
  • Enlarged lymph nodes, intermittent fever,
    itching, weight loss, night sweats
  • Risk factors
  • Altered immune function
  • Transplant recipients
  • HIV infection
  • Occupational exposure to herbicides
  • Treatment radiation, chemotherapy, bone marrow
    transplant

31
Common Cancers Urinary Bladder Cancer
  • Symptoms
  • Blood in the urine
  • Risk factors
  • Smoking, urban living, exposure to arsenic in
    water supply, occupational exposure to leather,
    dye, rubber
  • Diagnosis
  • Microscopic examination of urine for cancer cells
  • Cystoscopy direct examination of bladder wall
    with cystoscope (thin flexible tube with lens)
  • Treatment
  • Surgery with chemotherapy

32
Common Cancers Kidney Cancer
  • Risk factors
  • Genetics, smoking, exposure to certain toxic
    chemicals, age, gender (female)
  • No direct screening tests
  • Usually detected during examination for a
    renal-related problem
  • Diagnosis
  • CT scan or ultrasound
  • Treatment
  • Surgical removal of affected kidney

33
Common Cancers Skin Cancer
  • Three major types
  • Basal cell carcinoma
  • Involves basal cells in base layer of epithelium
  • Rarely metastasizes, but should be removed
  • Squamous cell carcinoma
  • Involves epithelial cells
  • May metastasize slowly
  • Melanoma
  • Deadliest, but least common of skin cancers
  • Cancer of the melanocytes
  • Metastasizes quickly

34
Early Signs of Skin CancerABCs
  • Observe skin lesions for
  • A ? Asymmetry
  • Two halves of the affected area dont match
  • B ? Border
  • Border is irregular in shape
  • C ? Color
  • Varies or is black
  • D ? Diameter
  • Greater than 6 mm (size of pea)

35
Figure 18.11
The two halvesof the spot orpatch dont match.
The borderis irregular.
A Asymmetry.
B Border.
The colorvaries or isintenselyblack.
The diameter isgreater than 6mm.
C Color.
D Diameter.
36
Common Cancers Uterine, Cervical Cancers
  • Uterine cancer
  • Involves the endometrium
  • Symptom abnormal bleeding
  • Risk factors
  • Early onset of menstruation, late onset of
    menopause, not having children, estrogen use
    after menopause
  • Cervical cancer
  • Caused by human papilloma virus (HPV) infection
  • Detection Pap test
  • Prevention Gardasil or Cervarix vaccines
  • Treatment surgery, chemotherapy, radiation,
    hormones

37
Table 18.3
38
Most Cancers Can Be Prevented
  • Know family history
  • Know your own body
  • Learn self-examination techniques
  • Get regular medical screenings
  • Avoid direct sunlight 10 a.m. to 4 p.m.,
    sunlamps, and tanning salons
  • Watch diet and weight
  • Dont smoke
  • Drink alcohol in moderation, if at all
  • Stay informed
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