Tumor Flashcards
What is the process by which a tumor cell exits the primary site into the vascular or lymphatic capillary bed?
Tumor metastasis
Intravasation
What are the enzymes that help degrade the extracellular matrix during tumor metastasis?
Tumor metastasis
Matrix metalloproteinases
What challenges must tumor cells overcome in the bloodstream?
Tumor metastasis
- Survive higher shear forces in vessels
- Evade the host immune system
- Resist apoptotic death via anoikis
What is the term for the process of tumor cells leaving the blood vessel?
Tumor metastasis
Extravasation
What factors are crucial for tumor survival at a distant site?
Tumor metastasis
- Ability to develop a new blood supply (angiogenesis)
- Recruit a supporting stroma/extracellular matrix
- Produce necessary growth factors
How close must tumor cells be to a capillary bed for continued growth and waste removal?
Tumor metastasis
100 to 200 µM
What factor is activated under hypoxic conditions that leads to the production of growth factors?
Tumor metastasis
Hypoxia-induced growth factor (HIF-1a)
Which growth factors are produced as a result of HIF-1a activation?
Tumor metastasis
- Vascular endothelial growth factor (VEGF)
- Basic fibroblast growth factor (BFGF)
- Hepatocyte growth factor (HGF)
- Platelet-derived growth factor (PDGF)
What are the three steps of a cell towards a malignant phenotype?
initiation -> promotion -> progression
What follows the first mutation in cancer formation?
Genetic factors of Cancer
a second mutation that promotes the growth advantage of a mutated cell over surrounding cells
What is initiation in chemical carcinogenesis?
Chemical Carcinogensis
when a cell’s DNA is exposed to a mutagen that causes base alterations in nuclear material
What must an initiated cell be exposed to in order to cause tumor growth?
Chemical Carcinogensis
a promoting agent
True or False: Tumor formation occurs if a promoting agent is exposed to a cell first, followed by the initiating agent.
Chemical Carcinogensis
False
Tumor formation does not occur if a promoting agent is exposed to a cell first, followed by the initiating agent.
Is initiation considered to be an irreversible or reversible step?
irreversible and reversible
Do all initiated cells go on to develop into clinically detectable neoplasia?
No
What do initiation and promotion clinically lead to?
benign lesions such as papillomas or polyps
What occurs during tumor progression?
gains the ability to invade surrounding tissue, establish new blood vessels (angiogenesis), and metastasize to regional and distant sites
What percentage of all tumors do thyroid tumors in dogs account for?
1% to 4%
In necropsy studies, what percentage of thyroid tumors are benign adenomas?
30% to 50%
What are the characteristics of thyroid adenomas in dogs?
Usually small, noninvasive, and without clinical signs
What percentage of clinically detected thyroid tumors in dogs are malignant?
90%
What are the characteristics of thyroid carcinomas in dogs?
Can be large, poorly encapsulated, extend locally into or around trachea, esophagus, and muscles of the neck, highly vascular, and invade local blood vessels
Approximately what percentage of thyroid carcinomas are bilateral?
25% to 47%
In what percentage of cases does the tumor arise from ectopic thyroid tissue?
13%
Where can ectopic thyroid tissue be located?
- Base of the tongue,
- Ventral neck
- Cranial mediastinum
- Heart base
Go throug the steps of metastatic cascade?
Detachment →
Migration →
Intravasation into a microvessel→
Survival of circulation →
Attachment to a distant endothelial cell →
Extravasation →
Angiogenesis → Proliferation
This refers to the separation of cancer cells from the primary tumor.
Metastatic cascade, definition of intravasation?
Intravasation -> entry of tumor cells into a vascular or lymphatics
What acts as the best biological barrier to neoplastic cells?
Fascia, bone and cartilage
These CT are resistant to neoplastic invasion and provide good natural tissue barrier
Samples of normal dog skin, fixed in formalin and then processed, have been shown to decrease in length and width by as much as ____ % and to increase in thickness by ____ % compared with their original dimensions.
- 32 %
- 75.8%
