10.1 Introduction to Cancer Flashcards
Leading Causes of Cancer Death
1 - Lung
2 - Prostate
3 - Colorectal (men)
Prevalence
- All cancer cases at a designated point in time
Incidence
- Newly diagnosed cases of cancer during a specific time in a defined population, per 100,000 people.
- Allows for comparisons between populations.
Cancer Developmental Stages
Initiation
- Mutation of cell’s genetic structure from genetic disposition or from exposure to chemicals, radiation or virus. REVERSIBLE BUT NOT PREVENTABLE
Promotion
- Reversible proliferation of altered cells. Numbers of mutation increases
Progression
- Increased growth rate of tumor, increased invasiveness, and possible metastasis.
Cancer
- Uncontrolled division of body cells
- Begins when cells break free of normal restraints on cell division and follow its own agenda for proliferation.
Tumor
- Mass of abnormal cells that remain in the tissue where it originated (situ cancer). When they invade nearby tissue it is called invasive cancer.
- Invasive tumors are malignant
- Metastasis is when the cells shed into blood or lymph and create new tumors.
- Tumors threaten individual life when growth disrupts tissue and organ needs for survival.
Pathophysiology of Cancer
- Cells fail to respond to homeostatic mechanism that controls normal cell birth and death processes.
- IT IS A GROUP OF DISORDERS
Cancer Cells
- Divide out of control
- ARE IMMATURE (do not develop into mature cells with specific jobs)
- Avoid the immune system
- Ignores signals that tell them to stop dividing or die
- Spread quickly through blood and lymphatic system
- Grow into and damage tissues/organs
Telomerase
- Enzyme that is active in most cancer cells but rare in normal cells
- This is what prevents ending of cell division
- Telomere (at the end of each chromosome) shortens which each cellular division and cannot divide anymore once it is gone.
- Normal cells do not invade territories of other cell types. Cancer cells do not follow this rule.
Cell Cycle
- Most of the time cells are in interphase (not dividing)
- Many cancer drugs go after cells that do cell division frequently (mitosis) like hair follicles.
Cell Cycle (Interphase) - Checkpoints
G1 - Is the cell growing enough (individually)
S - Replicates its DNA (synthesis)
G2 - Cell grows more to prepare for mitosis
Cell Cycle (End-phase) - Checkpoints
Mitosis - Makes sure the chromosomes are lined up in the middle of the cell correctly.
- Cells pause when when one of the checkpoints does not meet the requirements (such as DNA is not replicating properly or issues with DNA synthesis) They do this when the issue CAN BE FIXED
- If the ISSUE CANNOT BE fixed then cells go through apoptosis (programmed cell death) - So damaged cells to not divide.
Positive Regulators - Allow moving forward of cell division
CDK (cyclin-dependent kinase) helps cells move forward with division.
Negative Regulators - Slow down movement of forward of cell division
Protein called P53 initiates Apoptosis
G0 - Stay here when cells do not have resources to divide, or some stay there permanently so they do not ever divide.
Classifying Cancer
- Based on site (tumor location and tissue of origin)
- Grading and staging
- Prognosis
Types of Cancer
Carcinoma
- Cancer that begins in the skin or lining that covers internal organs (epithelial tissue)
Leukemia
- Cancer that starts in blood forming tissue such as bone marrow and causes large amounts of abnormal blood cells to enter the blood
CNS
- Cancer begins in the brain/spinal cord
Sarcoma
- Cancer that begins in bone, cartilage, fat, muscle, blood vessels or other connective or supportive tissue (connective or supportive tissue of the body)
Lymphoma/Myeloma
- Cancer begins in the immune system
- Myeloma originates in the plasma cells of the bone marrow
Grading of Cancer
- Based on appearance of cells and degree of differentiation
Grade 1 - Mild dysplasia (cells differ slightly) and well-differentiated
Grade 2 - Moderate Dysplasia and moderately differentiated
Grade 3 - Severe dysplasia and poorly differentiated
Grade 4 - Immature, primitive, undifferentiated. Cell origin is difficult to determine
Staging of Cancer
- Based on extent of disease
Stage 0 - Cancer in situ (has not spread)
Stage 1 - Limited to tissue of origin, localized tumor growth only
Stage 2 - Limited local spreading
Stage 3 - Extensive local and regional spreading
Stage 4 - Metastasis
Cancer Classification (TNM)
- Describes amount and spread of cancer in a patients body
T - Size of tumor (T 0-4) (Tumor)
N - Number of lymph nodes affected (N 0-4) (Node)
M - M0 means no metastasis and M1 means we do have metastasis (M: 0-1) (Metastasis)
Benign Tumors
- Well differentiated (mature) (resemble normal cells in which the tumor originated)
- Does not infiltrate surrounding tissue (usually encapsulated)
- Slow rate of growth
- Does not spread (metastasis)
- Localized and usually does not cause generalized effects UNLESS it interferes with vital functions
- Does not cause tissue damage UNLESS its location interferes with blood flow
- Does not usually cause death
Malignant Tumors
- Undifferentiated (immature) and may bear little resemblance to normal cells
- Overcomes inhibition of division and infiltrates surrounding tissue
- Rate of growth is variable (THE MORE ANAPLASTIC (loss of cell maturity) THE TUMOR, THE FASTER IT GROWS)
- Metastasis
- Often causes generalized effects (anemia, weakness, inflammation, weight loss)
- Causes extensive tissue damage
Endogenous Risks
- Increasing age
- Hormones
- Immune dysfunction
- Genetic background
Exogenous Risks
- Chemical carcinogens
- Drugs (chemotherapy and immunosuppressants)
- Tobacco
- Nutrition/physical Activity
- Radiation
- Viruses (Hep-B, Epstein-Barr, HPV)
