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5224 PBT > Exam 1 > Flashcards

Flashcards in Exam 1 Deck (59):
1

What is Cancer?

A disease of cells involving dynamic changes (i.e. mutations) in the genome leading to loss of the normal control mechanisms that govern Proliferation, Differentiation, & Programmed death (apoptosis)

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Proliferation

NOT always faster than normal cells, uncontrolled

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Differentiation

Dedifferentiation (different degree); lost differentiation

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Programmed death (apoptosis)

resistant to apoptosis

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Undifferentiated cancer cells

Poorly differentiated (immature) , they do not differentiate into mature specialized cells, they remain immature-looking.

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Tumorigenesis

malignant transformation; multi-step process: initiation, promotion, and progression

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Intravasion

Penetrating the muscle and get into circulation

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Extravasion

Get out of vessel and relocate to a new home and form a new mass

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Structural difference: Cancer Cells

Carry mutations including abnormal gene structure or numbers of chromosomes
Continue to be created without control or order. A Mass of tissue or tumor is formed

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Differences in Energy Use: Normal Cells

70% of their energy from the Krebs cycle
Only 20% of their energy from glycolysis

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Difference in Energy Use: Cancer Cells

Have a defective Krebs cycle and derive little or no energy from it.
Almost all their energy from glycolysis
Glycolysis even in the presence of oxygen (aerobic glycolysis)

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High aerobic glycolysis by malignant tumors is utilized to?

diagnose and monitor treatment responses of cancers by imaging uptake of 2-18F-2-deoxyglucose (a radioactive modified hexokinase substrate) with positron emission tomography (PET)

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Differences in Blood Vessels: Normal Cells

Have a built-in blood vessel system

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Differences in Blood Vessels: Cancer Cells

Do not have a built-in blood vessel system. They require some chemical stimulation to build one, because tumor growth depends on development of new blood supply (i.e., angiogenesis).

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Differences in Growth Factors: Cancer Cells

Overproduce growth factors.
Cells are overactive

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Functional Differences: Cancer Cells

The enzymes and hormones are either overactive or underactive

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Carcinomas

From epithelial cells (line some organs and skin).

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Sarcomas

From connective or other deeper tissues.

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Leukemia

Cancer of the blood

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Lymphoma

Cancer of the lymphatic system

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What does the term "solid tumor" distinguish between?

Distinguish between a localized mass of tissue (carcinoma, sarcoma, and lymphoma) and leukemia

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Cancer staging systems does not apply to what type of cancer?

leukemia -because the blood is not localized

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Cancer staging systems

describe how far cancer has spread anatomically (i.e. metastasis)

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For solid tumors there are two staging systems:

1. The overall stage grouping system
2. The tumor, nodes, and metastases (TNM) system

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This stage - Small localized cancers that are usually curable

Stages 0 and I

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Stages II and III

Locally advanced and/or involvement of local lymph nodes.

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Stage IV

Inoperable or metastatic cancer

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Tumor Grading

Measure of how abnormal cells appear under the microscope

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grade cannot be assessed (least aggressive)

Gx

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well differentiated

G1

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G2

moderately differentiated

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poorly differentiated

G3

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undifferentiated (most aggressive and fast growing)

G4

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Tobacco

Associated with upper respiratory tract, lung, esophageal, bladder, and pancreatic cancers

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Alcohol

Can cause cancer in upper GI tract by increasing permeability of mucosa to carcinogens.
Associated with hepatocellular carcinoma, pancreatic cancer, etc.

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Radiation: Solar

Skin cancer such as squamous and basal cell carcinoma and melanoma
Whitest skin, highest risk

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Ionizing radiation

Associated with development of leukemia and thyroid cancer

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Foods associated with increased risk of developing cancer such as colon, prostate, and breast

high fat, high calories intake
alcohol
salt cured, smoked or charred foods
nitrate and nitrite additives

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Aflatoxin

hepatoma

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Aromatic amines

bladder cancer

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Asbestos

lung, mesothelioma

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benzene

leukemia

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vinyl chloride

liver angiosarcoma

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Epstein-Barr virus

Non-Hodgkin’s lymphoma and nasopharyngeal cancer

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HIV

Kaposi’s sarcoma and lymphoma

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HTLV1

Cutaneous T-cell lymphoma

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Human papilloma virus

Cervical Cancer

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Hepatitis B virus

Liver Cancer

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What are the two main categories of genetic changes that lead to cancer?

The activation of proto-oncogenes to oncogenes
The inactivation of tumor suppressor genes

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Proto-Oncogenes

Proto-oncogenes are normal genes whose protein products stimulate growth and viability of cells.
Also include genes that contribute to tumor growth by inhibiting cell death (inhibiting apoptosis)(“Do not die”)

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Examples of Proto-Oncogenes

EGFR, HER2, BCL2

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Oncogenes

Oncogenes are mutated or damaged genes that contribute to tumor growth (oncogenes are defective proto-oncogenes)

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Activation of proto-oncogenes

Mutation or amplification (increased #of gene copies); chromosome abnormality (“Driver mutations”)
Increase of protein expression

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Tumor Suppressor Genes

Genes whose protein products can directly or indirectly prevent cell division or lead to cell death.

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Inactivation of tumor suppressor genes

Mutation or deletion
Decrease of protein expression

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Chemotherapy

the use of cytotoxic chemical agents to destroy cancer cells.

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Most chemotherapy drugs interfere with

Cell growth cycle

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Side effect profile of chemotherapy

Side effect profiles: hair follicles, bone marrow, skin, and the cells in GI tract (these are also fastest growing cells)

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Growth fraction

The ratio of the number of cells that are proliferating to the total number of cells in the tumor