Neoplasia 2 Flashcards
Define invasion
Breach of the basement membrane with progressive infiltration and destruction of the surrounding tissues
Define metastasis
Spread of tumour to sites that are physically discontinuous from the primary tumour
Describe the multi-step journey of metastasis
1) Grow and invade at primary site
2) Enter a transport system and lodge at a secondary site
3) Grow at secondary site to form a new tumour (colonisation)
What are the 3 key main events for a carcinoma cell?
1) Altered adhesion = reduction in E-cadherins, changes in integrin expression
2) Stromal protelysis = altered expression of proteases, degrade basement membrane and stroma to allow invasion
3) Motility = changes in the actin cytoskeleton
How does a malignant metaplasia spread to a distant site?
Through blood vessels, lymphatic vessels, fluid in body cavities (transcoelemic)
What is a micrometastases?
Surviving microscopic deposits of malignant neoplasm that failed to grow
What is the secondary site for metastasis through lymph nodes?
Draining lymph nodes
What is the secondary site for metastasis through transcoelemic spread?
Other areas in the coelemic space or to adjacent organ
What is the secondary site for metastasis through the blood stream?
Usually the next capillary bed (lung, bone, liver and brain)
What is the ‘seed and soil’ phenomenon?
A potential explanation for the unpredictable distribution of blood-borne metastases
-from interactions between malignant cells and the local tumour environment at the secondary site
How does the immune system recognise tumour cells?
Tumour antigens presented on the cell surface of major histocompatability complex molecules and are recognised by CD8+ cytotoxic T cells
How can tumours avoid the immune system (3)?
- Loss or reduced expression of histocompatibility antigens
- Expression of certain factors that suppress immune system
- Failure to produce tumour antigen
What are some local effects of neoplasms?
- Direct invasion and destruction of normal tissue
- Ulceration at a surface leading to bleeding
- Compression of adjacent structures
- Blocking tubes and orfices
- Raised pressure due to tumour growth or swelling
What are systemic effects of neoplasms?
- Increased tumour burden = parasitic effect on host
- Production of hormones
- Secreted factors (e.g. cytokines) can lead to: reduced appetite, weigh loss (cachexia), malaise, thrombosis
What are paraneoplastic syndromes?
Signs and symptoms that cannot readily be explained by the anatomic distribution of the tumour or by the production of hormones from the tissue which the tumour arose from e.g. hypercalcaemia
