Neoplasia II

Question 1

How is blood supplied to tumours? How is vascularisation important for tumours to progress?

Answer 1

Tumours are unable to enlarge beyond 1-2mm without being vascularised
Angiogenesis (generation of blood vessels) occurs in both benign and malignant neoplasms and is required for:
- Metabolism by tumour cells
- Sustained growth
- Metastasis of malignant tumours

Question 2

How do tumours produce their own blood vessels (angiogenesis)?

Answer 2

Tumours induce host vessels to supply brannches by production of tumour angiogenesis factors (TAFs) also lymphangiogenesis similar essential for lymphatic spread of tumours

Question 3

What is the morphology of tumour generated vasculature?

Answer 3

Tumour vessels tortuous, irregular, leaky leading to less efficient vessels
causes necrosis as blood supply not always sufficient

Question 4

Describe the Metastatic Cascade

Answer 4

1. Primary tumour
2. Detachment of the priamry tumour, penetration of the BM, and enter ECM by loosening tight intracellualr junctions, forming cell-ECM connections and degrading the BM and ECM by protease activity
3. Adhesion to vessel wall
4. Invasion of the vessel
5. Transport of micrometastasis
6. Evasion of host defences and platlet clumping
7. Exit from vessel and migration
8. Secondary tumour

Question 5

What is metastasis?

Answer 5

Spread of a primary tumour to another area of the body causing a secondary tumour
only malignant tumours metastasise

Question 6

What routes of metastasis are there?

Answer 6

1. Intravascular via either blood or lymphatics
2. Serosal spread
3. Intra-organ spread
4. Local invasion

Question 7

What is a paraneoplastic syndrome? What is the importance?

Answer 7

Systemic complications caused by neoplasia that are at a site away from the primary tumour important for:
- Diagnosis
- Specific tumour marker for treatment response and failure
- Often the effects of the PN syndromes can be more injurious than the malignanyc, and maybe the reason the animal was brought to the vet

Question 8

What is the pathogenesis of PN syndromes?

Answer 8

Caused by products of tumours - such as hormones and enzymes. Tumours of cells that produce hormones or ectopic production of hormone like substances by tumour cells that are not related to hormone producing cells
Also caused by antibodies produced against foreign tumour cells targetting other tissue types

Question 8

What is the pathogenesis of PN syndromes?

Answer 8

Caused by products of tumours - such as hormones and enzymes. Tumours of cells that produce hormones or ectopic production of hormone like substances by tumour cells that are not related to hormone producing cells
Also caused by antibodies produced against foreign tumour cells targetting other tissue types

Question 9

How do we prove PN syndromes?

Answer 9

• When removal of a tumour reduces the concentrations of the product/clinical signs
• When removal of the gland that produces the hormone doesn’t reduce clinical signs/concentration
• A positive ateriovenous concentration gradient exists across the tumour
• In vitro synthesis of prodcut occur