Cancer Flashcards
2nd stage : promotion
Promoting agents:
- single altered cell will not cause cancer but in presence of promoters increase odds
• accelerates the process
-promoters
Obesity, smoking, alcohol consumption , prolonged sever stress, fat in diet, hormones, nutrition, infections.
•reversible if promoters are removed
3 stages of cancer development
Stage 1: Initiation
Mutation in the cells genetic structure.
- activate proto-oncogenes or inactive tumor suppressor genes.
- carcinogens that can alter a cells genes
•chemical carcinogens: > 6 million chemicals
-polycyclic hydrocarbons: cigarette smoke, tars
-industrial agents: vinyl chloride, asbestos, benzene
-food and drugs:anti cancer drugs, smoked food, nitrosamines
(Alcohol modifies metabolism of carcinogens in liver and esophagus.. Enhances effect of cigarette smoke.
-tobacco ( chewing and smoking)
• related to lung cancer (30% of lung ca deaths r/t to tobacco)
• linked also to cancersin : pancreas, kidney, bladder, larynx, esophagus and cervix
• chemicals in smoking are the initiators and act as promoters.
-radiation:damage DNA
-ionizing radiation (atomic bomb) & UV rays
-viruses: DNA and RNA viruses transform the cells they infect
-hormones
-des in 1st trimester and increased vaginal carcinoma in female offspring.
3rd stage: progression
Characterized by: increased growth rate of tumor, increased invasive mess, metastasis
- metastasis: spread from initial site to distant site.
• multistep process
-rapid tumor growth
-tumor angiogenesis
-invasion (local spread into surrounding tissue)
-hematogenous metastasis
Hematogenous metastasis
- Once tumor cells free of primary tumor release enzymes that penetrate basement membrane of blood vessels and lymph
- enter blood vessel and float until adhere to vessel wall.
- secrete enzymes to degrade basement membrane and move into interstitial tissue and proliferate.
- while floating 1/10,000 cells are destroyed by immune resonse.
staging of tumors
Staging
Describes the location, and pattern of spread of a tumor within the host. Factors such as tumor size, extent of local distant metastasis are considered. TNM (tumor, node, metastasis) system is used extensively as a general framework for staging tumors.
Grading
Refers to the histologic characterization of tumor cells and is basically a determination of the degree of anaplasia. Most grading systems classify tumors into 3 or 4 classes of increasing degrees of malignancy. A greater degree of anaplasia indicates a greater malignant potential.
Grading of tumor
Evaluation of the extent to which tumor cells differ from normal precursors.
Grade 1: well-differentiated with minimal deviation from tissue of origin
Grade 2: moderately well differentiated with evidence of structural changes from normal tissue of origin.
Grade 3- poorly differentiated (hardly) looks like original tissue) with extensive structural changes from tissue of orgin.
Grade 4: very anaplastic with no resemblance to tissues of orgin.
Incidence rate
The # of new cases in a give population
Mortality rate
The # of deaths in a total population in specific time period. Helps describe trends.
Prevalence
The # of individuals who have given disease in given population over specific period of time.
% 2010 estimated cancer deaths
Lung cancer is by far the most common fatal cancer in men 29%, followed by prostate 11% and rectum 9%.
In women lung 26%, breast 15%, and colon and rectum 9%
Normal cell vs cancer cell
Normal: large cytoplasm, single nucleus, single nucleolus, fine chromatin
Cancer: small cytoplasm, multiple nuclei, multiple and large nucleoli, coarse chromatin.
Differentiation
Process by which cells attain structure & functional characteristics
All cells derive from ova- have potential to perform all body functions
Then cells differentiate into specialized committed cells: repress all potential functions and express only the genes related to cell’s specific functions.
Proliferation
Process in which cells divide and reproduce
-normally controls prevent excess proliferation: (dynamic equilibrium)
-contact inhibition
-activation only when new cells needed. (Ie infection- WBC s proliferate
–or when cells degenerate
- rate of normal proliferation differs depending on cell type
. Some tissues don’t proliferate at all ( cardiac, neurons)
Some proliferate rapidly -bone marrow and epithelial.
Cancer cells and proliferation
Proliferate indiscriminately and haphazardly
-stem cell theory- mutation of stem cell ( a predetermined undifferentiated cell)
-a stem cell of a certain tissue will become a mature, functioning cell of that tissue of orgin.
Mutated stem cells
- die from the mutation-apoptosis
-recognize damage and repair itself.
-or pass on mutation to daughter cells and become malignant
Rate
: not faster than normal.. Just more cells proliferating
- pyramid effect
- doubling time: time required for tumor mass to double
