Metastasis Flashcards
What is metastasis?
Spread of cancer from one part of the body to another part not directly related to it
How does cancer metastasise, briefly?
The cancer cells become invasive and escape from the tumour.
Then they can travel around the body via bloodstream or lymph system to another part of the body
Describe how metastasis occurs?
7 steps
- Invade basement membrane
- Move through extracellular matrix by cell motility
- Get into blood stream or lymph vessels
- Evasion of host immune system & lymphocytes
- Get out of blood/lymph vessels at the other end
- Grow at metastatic site
- Develop a blood supply at new site
How do cancer cells invade the basement membrane at their primary site?
They produce agents that help them do this:
- Proteases
- Collagenases
- Cathepsin D
The also use their cell motility
How do cancer cells move through extracellular matrix?
By cell motility
They have tumour cell derived motility factors
They break down the extracellular matrix
How to cancer cells get into the blood stream or lymph vessels?
Collagenases to break vessel wall so they can get in
Cell motility
How do cancer cells evade the host immune system?
Aggregation with platelets, they hide behind platelets
They shed their surface antigens
They adhere to other tumour cells
How do cancer cells get out of the vessels at the other end?
Collagenases to break vessel wall so they can get out
Cell motility
Adhesion factors
How do cancer cells grow a blood supply at the metastatic site?
Angiogenesis promoters:
- vascular endothelial growth factor
- basic fibroblast growth factor
What are angiostatin, endostatin & vasculostatin?
Angiogenesis inhibitors!
These are good for stopping cancerous tumours growing
Where do sarcomas commonly metastasise to?
Lung
Which cancers commonly metastasise to the liver?
Colon, stomach, pancreas, carcinoid tumours of intestine
