Invasion & Metastasis Flashcards
In-situ neoplasia
-epithelial neoplasms, eg. carcinoma
-may progress to invasive disease
-basement membrane is intact
-screening may allow detection & treatment before development of carcinoma
Carcinoma in-situ
-a malignant epithelial neoplasm
-that has not yet invaded through the original basement membrane
Invasive carcinoma
-a carcinoma that has breached the basement membrane
-it can now spread elsewhere
Micro-invasive carcinoma
-has breached the basement membrane
-but hasn’t invaded very far away from the original carcinoma
What is invasion?
-defining feature of malignant neoplasm
-enables the neoplastic cells to spread directly through tissue & gain access to blood vessels & lymphatic channels
What is invasion by neoplasms dependent on?
-decreased cellular adhesion
-abnormal cellular motility
-production of enzymes with a lytic effect on surrounding tissues
Metastasis
Process by which a malignant tumour spreads from its primary site to produce secondary tumours at distant sites
What can metastasis occur via?
-blood vessels
-lymphatics
-across body cavities
-along nerves
-direct implantation of neoplastic cells during a surgical procedure
7 stages of the metastatic cascade
DETACHMENT
INVASION - through BM
INTRAVASATION - enter blood/lymphatic vessels
-collagenases
-cell motility
EVASION OF HOST DEFENCES
-aggregation with platelets
-shedding of surface antigens
-adhesion to other tumour molecules
ARREST
EXTRAVASTION - leave blood/lymphatic vessel - enter tissue
-adhesion receptors
-collagenases
-cell motility
VASCULARISATION
How does growth occur at the metastatic site?
-autocrine growth factors
-after 1mm diameter - angiogenesis (they begin to grow their own BVs)
Angiogenesis
Formation of new BVs
Angiogenesis promoters
-vascular endothelial growth factors
-basic fibroblast growth factor
Angiogenesis inhibitors
-angiostatin
-endostatin
-vasculostatin
Routes of metastasis
-invade arterial side - if it grows large enough & breaks off
-haematogenous - by the bloodstream - secondary tumours form in organs perfused by blood that has drained from a tumour
-lymphatic - lymph channels - secondary tumours form in the regional lymph nodes
-trans-coelomic - pericardial & peritoneal cavities - results in neoplastic effusion
Neoplastic effusion
Effusion where a neoplastic cell population has been identified in the fluid
