Lecture 10 Flashcards
Mechanisms of control for cell growth
Constant renewal (Hair follicles, gut lining), Stable, but can renew when stimulated (T-cells), Permanent, therefore, no renewal (cardiac muscle)
How is cancer developed?
Loss of control of cell division/ mutation of a gene
Characterization of Cancer tumours
Benign vs. Malignant
Solid vs. Invasive
In situ vs. Infiltrating
Benign Tumor characteristics (Growth rate, Character of growth, Tumor spread, Cell differentiation)
Growth rate: Slow
Character of growth: Expansion
Tumor spread: Localized (Brain tumors can do damage while being benign)
Cell differentiation: Well differentiated
Malignant Tumor characteristics (Growth rate, Character of growth, Tumor spread, Cell differentiation)
Growth rate: Fast
Character of growth: Infiltration
Tumor spread: Metastasis by bloodstream and lymphatics (establish secondary sites)
Cell differentiation: Poorly differentiated
Benign tumor classification
The cell of origin (Prefix-) and -oma (suffix)
Malignant tumor classification
3 groups (carcinoma, sarcoma, leukemia/lymphoma)
Carcinoma cancer
Most common (85% of tumors); Epithelial tissue (arises from the surface, glandular or parenchymal epithelium) and spreads through lymph nodes
Adenocarcinoma
Subtype of carcinoma cancer (ex. pancreas - glandular/ secretory cells)
Squamous cell carcinoma
Subtype of carcinoma cancer found on skin
Sarcoma cancer
Less common; Arise from connective tissue, endothelium, and mesothelium and spreads rapidly through the bloodstream
Fibrosarcoma
A subtype of sarcoma cancer affects fibroblasts
Myosarcoma
A subtype of sarcoma cancer affects muscles
Leukemia
Neoplasm of blood cells; non-solid tumors and overgrows and crowds out normal blood-forming cells
What happens if neoplasm cells populate LN and spleen
Lymphoma (T cell/ B cell)
Neoplasm development
A stepwise process that involves ongoing series of genetic changes over time (activation of oncogenes, loss of function of one or more tumor suppressor genes, and additional random genetic changes)
What does cancer in stem cells cause?
A tumor with a high degree of heterogeneity
True or False: Fast-growing neoplasms may outgrow the blood supply
True, this can be used as a therapeutic target
True or False: Tumors have their own blood supply
False, tumors derive blood supply from tissues they invade
Angiogenesis
Malignant tumors frequently induce new blood vessels to proliferate in adjacent normal tissues to supply the demands of the growing tumor
Necrosis in parts of malignant tumors
When the tumor outgrows its blood supply part with the poorest blood supply undergoes necrosis
The blood supply in tumors in the lung
Blood supply is best at the periphery of the tumor and poorest at the center (central necrosis)
The blood supply in tumors growing outward from an epithelial surface (ex. colon)
The best blood supply is at the base and the poorest at the surface (peripheral necrosis)
How can genetic change occur in cancer-causing genes?
Radiation, carcinogens, viruses – failure of DNA repair/fidelity mechanisms, Failure of Immune defences, over time these can accumulate (age-dependent), can also be inherited susceptibilities to developing cancer
Proto-oncogene
Philadelphia chromosome – seen in chronic granulocytic leukemia (translocation of pieces of chromosome 9 and 22); a very aggressive cancer
Loss of apoptotic control leads to…
Uncontrolled cell growth and cells eventually form a tumor
Tumor-suppressor genes
Genes (expressed in pair of homologous chromosomes) that inhibit/control cellular division/proliferation; prevent DNA replication (ex. APC, DCC, p53)
What virus causes leukemia and lymphoma?
T cell leukemia–lymphoma virus (HTLV-1) that is related to the AIDS virus (tax onocogene)