Cancer Flashcards
the cell cycle
-a sequence of growth stages that a cell moves through for mitosis and regeneration
-in order for cells to undergo mitosis, the cells must go through stages G0, G1, S, G2, and M
stage G0
cell is at rest, and not actively engaged in the cell cycle
stage G1
-cells enter the cell cycle and prepare for DNA replication
-proto-oncogenes are activated- genes that control cell replication
stage S
-synthesis of structures occurs and the structures move to opposite poles in preparation for division into 2 separate cells. 2 nuclear membranes develop around the two separate sets of 23 pairs
stage G2
cells prepare to divide
stage M
mitosis is completed and two daughter cells are created
cancer cells
-constantly moving through the cell cycle stages
-no checkpoints: no DNA errors recognized, and no apoptosis
-disregard the growth inhibitors released by neighboring cells
-as they proliferate, they accumulate on top, around, and beside each other, take over boundaries of organs, crowd out normal cells, and may even break free and travel to distant sites
immune surveillance
-our immune system constantly surveys the body for foreign substances or non self antigens
-when a “non self” antigen is discovered, the immune system initiates an attack to destroy the invading substance
-with age, the strength of the immune system diminishes and tumor development becomes easier
differentiation
-refers to the extent that neoplastic cells resemble normal cells both structurally and functionally
-lack of differentiation is called anaplasia, a term that indicates total cellular disorganization, abnormal cell appearance, and cell dysfunction
benign tumors
-well differentiated, resembles tissue of origin
-progressive, slow rate of growth
-local invasion-cohesive cells, well demarcated tumor, often encapsulated making it movable
-no metastasis
-no necrosis in tumor core
malignant tumors
-poorly differentiated; does not resemble tissue of origin
-erratic, slow to rapid rate of growth
-local invasion- invasive and infiltrating, surrounding normal tissue
-frequent metastasis
-can have necrotic core
examples of tumor markers
-PSA
-BRCA
tumor grades:
-grade 1: cells are well differentiated
-grade 2: cell are moderately differentiated
-grade 3: poorly differentiated or anaplastic cells
TNM system
-T tumor size, location and involvement
-N-lymph node involvement
-M- metastasis to distant organs
four stage classification system
-stage 1: confined to organ of origin
-stage 2: locally invasive
-stage 3: regional spread
-stage 4: spread to distant sites
-important component of cancer diagnosis
4 phases of carcinogenesis
-initiation
-promotion
-progression
-metastasis
tumor suppressor genes
-normally function to restrain cell growth
-can also become defective and lose the ability to inhibit cell growth and division, thus allowing cancer formation
-the P53 gene is the tumor suppressor gene in cells that controls cellular apoptosis
proto oncogenes
-stimulate and regulate a cells movement through the cell cycle, resulting in cell growth and proliferation
-when mutated, proto oncogenes become oncogenes that stimulate constant, unrelenting cellular proliferation and cell cycling
carcinogens
-substances that cause development of cancer
-can alter cell DNA
-damage=cumulative
-classification: known, probable, possible
promoters
-agents that promote development of cancer
-examples: diet, alcohol, tobacco, hormones
viral induced cancer
-certain malignancies are associated with cancer inducing viruses
-for any virus to live and propagate, it must insert its genes into the host cells genome
-the host cell then becomes a manufacturer of the virus
-MOA: always involve the activation of growth promoting pathways or inhibition of tumor suppressors in infected cells
metastasis and angiogensis
-cancer cells are suited for this task because they secrete vascular endothelial growth factor, a substance that gives them the capability to develop new blood vessels
metastasis: terminology
primary tumor- location- where did it start?
-secondary tumor- location- not original starting location
cancer spread: seeding, implantation, metastasis
-seeding- intraperitoneal
-implantation- direct expansion of tumor to adjoining tissue
-metastasis: lymphatic and vascular
lymphatic spread
-first stop is the lymph system
-cells trapped in lymph nodes
-3 possible scenarios- death, dormancy, flourish/proliferate
vascular spread
-spread by vascular drainage- penetrate local veins
-first stop is often the liver
secondary tumors
-need nutrients and oxygen
-need access to blood- angiogenesis (make own blood supply)
-most common: lungs, bone, liver, brain
common metastatic sites
-lung- bone, brain
-colon- liver
-breast- bone, brain, liver, lung
-prostate- vertebrae
-melanoma-brain
