Download of cancer

Cancer: Part 1
Biology, Classification,
Diagnosis
Chapter 16
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cancer
• Group of more than 200 diseases
• Characterized by uncontrolled and
unregulated growth of cells
• Occurs in people of all ages
• 77% of cases are diagnosed in those
over age 55.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cancer
• More than 1.6 million persons are
expected to be diagnosed with
invasive carcinoma in 2013.
• Excluding basal and squamous cell skin
cancers
• Incidence has been declining since the
1990s.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cancer
• Mortality rates are declining.
• Incidences of lung, colorectal,
breast, and oral cancer have ↓
• Largely due to preventive efforts
• Other cancers have ↑
• Leukemia, liver cancer, skin cancers
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Cancer
• Higher in men than women
• Second most common cause of
death in the United States after
heart disease
• Leading cause of death in people less
than 85 years of age
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Cancer
• 5-Year survival rate is now 68% for
those who are
• Disease free
• In remission
• Under treatment
• Does not include number of people
who are “cured” of cancer
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Biology of Cancer
• Two major dysfunctions in the
process of cancer development:
1.
Defective cell proliferation (growth)
2.
Defective cell differentiation
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Defective Cell Proliferation
• Stem cells
• Undifferentiated cells
• Ultimately differentiate and become
mature, functioning cells of only that
tissue
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Defect in Cellular Proliferation
• All cells are controlled by an
intracellular mechanism that
determines proliferation.
• Cancer cells grown in culture are
characterized by loss of contact
inhibition.
• Grow on top of one another and on top of
or between normal cells
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Defect in Cellular Proliferation
• Cancer cells respond differently than
normal cells to intracellular signals
regulating equilibrium.
• Divide indiscriminately
• Divide haphazardly
• Can produce > 2 cells during mitosis
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Defect in Cellular Proliferation
• Pyramid effect
• Exponential growth of cancer cells
from continuous and indiscriminate
proliferation
• 1 X 2 X 4 X 8 X 16 X 32…….
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Normal Cellular Differentiation
• Orderly process progressing from a
state of immaturity to a state of
maturity
• Stable and will not change
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Defect in Cellular Differentiation
• Tumor suppressor genes
• Function to regulate cell growth
• Prevent cells from going through the cell
cycle
• Mutations make them inactive.
• Result in loss of suppression of tumor
growth
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Process of Cancer Development
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Development of Cancer
• Initiation
• 1st stage
• Mutation of cell’s genetic structure
• Any change in the usual DNA sequence
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Gene Mutations
• Inherited
• 5% of all cancers or the predisposition
to the cancers are inherited.
• Lead to a very high risk for cancer
• Acquired
• Most cancers are acquired.
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Carcinogens
• Cancer-causing agents capable of
producing cell alterations
• Many are detoxified by protective
enzymes and are harmlessly excreted.
• Failure of protective mechanisms
allows them to enter the cell’s nucleus
and alter DNA.
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Development of Cancer
• Carcinogens may be
• Chemical
• Radiation
• Viral
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Development of Cancer
• Chemical carcinogens
• Many chemicals have been identified
as carcinogens over the years.
• Long latency period makes
identification of carcinogens difficult.
• Certain drugs have been identified as
carcinogens.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Development of Cancer
• Radiation
• Radiation can cause cancer in almost any
human tissue.
• Damage occurs to the DNA.
• Ultraviolet radiation is associated with
melanoma and squamous and basal cell
carcinoma.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Development of Cancer
• Viral carcinogens
Virus
Associated Cancer
Epstein-Barr virus (EBV) Burkitt’s lymphoma
Human immunodeficiency Kaposi sarcoma
virus (HIV)
Hepatitis B virus
Hepatocellular
carcinoma
Human papillomavirus
Squamous cell
carcinomas
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Development of Cancer
• Promotion
• Characterized by reversible
proliferation of altered cells
• Activities of promotion are reversible.
• Obesity
• Smoking, alcohol
• Dietary fat
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Development of Cancer
• Latent period
• May range from 1 to 40 years
• Length of latent period associated with
mitotic rate of tissue of origin and
environmental factors
• For disease to be clinically evident, tumor
must reach a critical mass that can be
detected.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Development of Cancer
• Progression
• Characterized by
• Increased growth rate of tumor
• Invasiveness
• Metastasis
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Main Sites of Metastasis
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Pathogenesis of Cancer
Metastasis
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Development of Cancer
• Progression
• Metastasis process begins with rapid
growth of primary tumor.
• Develops its own blood supply
• Tumor angiogenesis
• Tumor cells can detach and invade
surrounding tissues.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Development of Cancer
• Progression
• Metastasis process
• Detached cells can invade lymph nodes
and vascular vessels to travel to distant
sites.
• Most mobile tumor cells do not survive.
• Surviving tumor cells must create an
environment conducive to growth and
development.
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Role of Immune System
• Immune response is to reject or
destroy cancer cells.
• May be inadequate as cancer cells arise
from normal human cells
• Some cancer cells have changes on
their surface antigens.
• Tumor-associated antigens (TAAs)
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Tumor-Associated Antigens on
Cell Surface
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Role of Immune System
• Immunologic surveillance
• Response to TAAs
• Lymphocytes continually check cell
surface antigens and detect and
destroy abnormal cells.
• Involves cytotoxic T cells, natural killer
cells, macrophages, and B cells
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Role of Immune System
• Cytotoxic T cells
• Kill tumor cells directly
• Produce cytokines
• Natural killer cells and activated
macrophages can lyse tumor cells.
• B cells produce antibodies that bind to
tumor cells.
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Role of Immune System
• Immunologic escape
• Mechanism by which cancer cells
evade immune system
• Suppression of factors that stimulate T
cells
• Weak surface antigens allow cancer cells
to “sneak through” surveillance.
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Role of Immune System
• Immunologic escape
• Develops tolerance to immune system by
some tumor antigens
• Suppresses immune response from
products secreted by cancer cells
• Induction of suppressor T cells
• Blocking antibodies bind TAAs,
preventing recognition.
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Tumor Escape Mechanism
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Benign vs. Malignant Neoplasms
• Tumors can be classified as benign or
malignant.
• Ability of malignant tumor cells to
invade and metastasize is the major
difference between benign and
malignant neoplasms.
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Classification of Cancer
• Tumors can be classified by
• Anatomic site
• Histology
• Grading severity
• Extent of disease
• Staging
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Classification of Cancer
• Classification systems provide a
standardized way to
• Communicate with health care team
• Prepare and evaluate treatment plan
• Determine prognosis
• Compare groups statistically.
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Classification of Cancer
• Anatomic site classification
• Identified by tissue of origin
• Carcinomas originate from
• Embryonal ectoderm (skin, glands)
• Endoderm (mucous membrane of
respiratory tract, GI and GU tracts)
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Classification of Cancer
• Anatomic site classification
• Sarcomas originate from
• Embryonal mesoderm (connective tissue,
muscle, bone, and fat)
• Lymphomas and leukemias originate
from
• Hematopoietic system
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Classification of Cancer
• Histologic classification
• Appearance of cells and degree of
differentiation are evaluated to
determine how closely cells resemble
tissue of origin.
• Poorly differentiated tumors have a
worse prognosis than those closer in
appearance to normal cells.
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Classification of Cancer
• Four grades of abnormal cells
• Grade I
• Cells differ slightly from normal cells and
are well differentiated.
• Grade II
• Cells are more abnormal and moderately
differentiated.
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Classification of Cancer
• Four grades
• Grade III
• Cells are very abnormal and poorly
differentiated.
• Grade IV
• Cells are immature and primitive and
undifferentiated.
• Cell of origin is difficult to determine.
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Classification of Cancer
• Clinical staging classifications
• 0: Cancer in situ
• 1: Tumor limited to tissue of origin;
localized tumor growth
• 2: Limited local spread
• 3: Extensive local and regional spread
• 4: Metastasis
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Classification of Cancer
• TNM classification system
• Anatomic extent of disease is based on
three parameters:
• Tumor size and invasiveness (T)
• Spread to lymph nodes (N)
• Metastasis (M).
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Diagnoses of Cancer
• Patient may experience fear and anxiety.
• You should
• Actively listen to patient’s concerns.
• Manage your own discomfort.
• Give clear explanations; repeat if necessary.
• Give written information for reinforcement.
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Diagnoses of Cancer
• Diagnostic plan includes
• Health history
• History of present illness
• Identification of risk factors
• Physical examination
• Specific diagnostic studies
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Diagnoses of Cancer
• Indicated diagnostic studies depend
on site of cancer
•
•
•
•
•
Cytology studies
Chest x-ray
CBC, chemistry profile
Liver function studies
Endoscopic examinations
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Diagnoses of Cancer
• Indicated diagnostic studies depend
on site of cancer
•
•
•
•
•
Radiographic studies
Radioisotope scans
PET scan
Tumor markers
Genetic markers
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PET scan
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Diagnoses of Cancer
• Indicated diagnostic studies depend
on site of cancer
• Molecular receptor status
• Bone marrow examination
• Biopsy
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Diagnoses of Cancer
• Biopsy involves histologic
examination by a pathologist of a
piece of tissue.
• Tissue may be obtained by
• Needle or aspiration
• Incisional procedure
• Excisional procedure.
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Prevention and Detection of
Cancer
• Lifestyle habits to reduce risks:
• Practice recommended cancer
screenings.
• Practice self-examination.
• Know seven warning signs of cancer.
• Seek medical care if cancer is suspected.
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Prevention and Detection of
Cancer
• Lifestyle habits to reduce risks:
• Avoid or reduce exposure to known or
suspected carcinogens:
• Cigarette smoke, excessive sun exposure
• Eat a balanced diet.
• Limit alcohol intake.
• Exercise regularly.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Prevention and Detection of
Cancer
• Lifestyle habits to reduce risks:
• Maintain a healthy weight.
• Get adequate rest.
• Eliminate, reduce, or cope with stress.
• Have a regular health examination.
• Be familiar with your family history.
• Know your risk factors.
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Audience Response Question
A nurse plans a community education program
related to prevention of the cancer with the highest
death rates in both women and men. What should
the nurse include in the teaching plan?
a.
b.
c.
d.
Smoking cessation
Screening with colonoscopy
Regular examination of reproductive organs
Use of sunscreen as protection from ultraviolet light
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