Pathophysiology Review Flashcards
What is cancer?
- Term used for diseases in which abnormal cells divide without control and are able to invade other normal healthy tissues
- Can spread to other parts of the body by the blood and lymph systems
- All Ca’s are believed to be changes in DNA (which make up genes), which make the genes fail to do their jobs and therefore cause problems
What are the three models of cancer development?
1) Clonal model
2) Cancer stem cell model
3) Inflammation theory
What is the clonal model?
- Suggests initial damage to DNA results in benign tumor growth
- Over time, inheritable genetic changes accumulate and encourage transformation of normal cells into malignant cells
- As more variants in the DNA accumulate, malignant characteristics rapidly proliferate at the expense of less-fit clones
What is the cancer stem cell model?
- Cancer is caused by mutated corrupt heterogeneous cancer stem cells
- Among cancer cells, a few act as stem cells that reproduce themselves and sustain Ca growth
- As the tumor grows, the stem cells can enter a rest phase and move back into an active phase years later; this model explains why Ca can return after treatment (therapy affect will be minimal if these stem cells aren’t replicating)
- A variant of this model is the plasticity model, which suggests that non-cancer stem cells with low potential to become tumors can convert to aggressive cancer stem cells
What is the inflammation theory of cancer?
Infectious agents and their inflammatory affects, plus chronic inflammation, are the primary cause of cancer
What are the different characteristics between malignant and benign tumors?
MALIG:
- Vascular (think angiogenesis)
- Metastatic
- Increased recurrence
BEN:
- Encapsulated
- Well differentiated
Define differentiation:
- The process where immature cells become mature cells with specific functions
- In Ca refers to how much or little the tumor tissue looks compared with normal tissue (well = close to normal looking, slow growth) (poor = different, grow fast)
What causes metastatis?
Cell breaks off from tumor > enters extracellular space > hormones from tumor cells breaks down basement membrane, allowing cells to break into blood and lymph vessels > tumor cells roll along the vessel endothelial lining until they adhere and enter a new site
What is carcinogenesis?
The process of transforming a cell into a cancer cell over 3 phase: initiation, promotion and progression
What is the initiation phase of carcinogenesis?
Cells are exposed to an initiating agent, making cells more suspectible to malignant transformation (essentially irreversible DNA changes)
What is the promotion phase of carcinogenesis?
- Promoting agents/carcinogens cause unregulated cell growth in previously initiated cells
- Reversible if promoting agents are removed early (eg. drugs, chemicals, hormones)
- Many chemical carcinogens are called a complete carcinogen because they both initiate and promote malignant transformation (eg. smoking)
What is a complete carcinogen?
A carcinogen that both initiates and promotes malignant transformation in carcinogenesis (eg. smoking)
What is the progression phase of carcinogenesis?
Tumor cells acquire malignant characteristics that include change in growth rate and invasive potential
How does cancer spread?
Either by direct invasion into surrounding tissues or by metastasis to distant areas via blood and lymph systems
What are the hallmarks of cancer (aka. the six acquired capabilities) of Ca?
1) Ability to sustain proliferation (rapidly producing of new cells) signaling
2) Evasion of growth suppressors
3) Replication immortality (continuous cell cycles with no G0 resting phase and no apoptosis)
4) Resistance of cell death
5) Deregulation of defective DNA repair
6) Angiogenesis
7) Evasion of immune system
What is a squamous cell carcinoma?
Malignant, squamous epithelium tumour
What is a teratoma?
Benign embryonic tumor
What is an adenocarcinoma?
Malignant, ductal/glandular tumor