Lecture 9.1: Invasion & Metastasis and the Effects of Neoplasms Flashcards
What is a Neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed
What is a Malignant Neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed and invades surrounding tissue with potential to spread to distant sites
What is Neoplasia?
A disorder of cell growth, triggered by a series of mutations (germline, acquired, somatic) affecting a single cell and its clonal progeny
What is a Tumour?
• Any clinically detectable lump or swelling
• A neoplasm is just one type of tumour
What is Cancer?
• A cancer is any malignant neoplasm
What is Metastasis?
- A malignant neoplasm that has spread from its
original site to a new non-contiguous site - The original location is the primary site
- The place to which it has spread is a secondary site
What is Dysplasia?
- A pre-neoplastic alteration in which cells show
disordered tissue organisation - It is not neoplastic because the change is reversible
How to Name Neoplasms?
• Benign neoplasms ends in –oma.
• Malignant neoplsams end in –carcinoma: if it is an epithelial malignant
neoplasm (90% malignant tumours)
• – sarcoma if it is a stromal malignant neoplasm
What are the 2 types of carcinomas?
• In-situ (no invasion of epithelial basement membrane)
• Invasive (penetrated through basement)
What is a Benign Neoplasm of Fibrous Tissue called?
Fibroma
What is a Benign Neoplasm of Smooth Muscle called?
Leiomyoma
What is a Benign Neoplasm of Striated (Skeletal) Muscle called?
Rhabdomyoma
What is a Benign Neoplasm of Bone called?
Osteoma
What is a Benign Neoplasm of Cartilage called?
Chondroma
What is a Benign Neoplasm of Fat called?
Lipoma
What is a Benign Neoplasm of Nerves/Nerve Sheath called?
Neuroma/Neurofibroma
What is a Benign Neoplasm of Glial Cells called?
Glioma
What is a tumour of glandular tissue called?
Adenocarcinoma/Adenoma
What is a Melanoma?
Malignant tumour of cells derived from neural crest
What is a Mesothelioma?
Tumour of mesothelium (malignant)
What does the suffix -blastoma refer to?
Tumours that arise from precursor cells and are composed of cells with immature characteristics seen in developing (embryonic) stages
What is the origin of a Carcinoma?
Refers to a malignant neoplasm of epithelial origin or cancer of the internal or external lining of the body
What is the origin of an Adenocarcinoma?
Which develops in an organ or gland
What is the origin of a Squamous Cell Carcinoma?
Which originates in the squamous epithelium
What is the origin of a Sarcoma?
Sarcoma refers to cancer that originates in supportive and connective tissues such as bones, tendons, cartilage, muscle, and fat
What is the origin of a Myeloma?
Originates in the plasma cells of bone marrow
What is the origin of a Leukemia?
Cancers of the bone marrow
Affect WBCs and RBCs
What is the origin of Lymphomas?
Develop in the glands or nodes of the lymphatic system, a network of vessels, nodes, and organs (specifically the spleen, tonsils, and thymus) that purify bodily fluids and produce infection-fighting white blood cells, or lymphocytes
Hodgkin Lymphoma vs Non-Hodgkin Lymphoma
The presence of Reed-Sternberg cells in Hodgkin lymphoma diagnostically distinguishes Hodgkin lymphoma from Non-Hodgkin lymphoma
Early in female embryogenesis one allele is randomly inactivated in each cell, what is this called?
Lyonisation
Main steps involved in invasion of extracellular matrix (4 Steps)
- Detachment of tumour cells from one another by
unzipping of the anchor protein E-cadherin - Degradation of the extracellular matrix by
collagenase attacking the collagen fibres of the
basement membrane - Loss of adhesion of cells from integrins
- Migration of tumour cells through the extracellular
matrix
Stromal invasion involves 5 important alterations
- The cells must degrade basement membrane
and stroma to invade - This involves altered expression of proteases,
notably matrix metalloproteinases (MMPs) - Malignant cells take advantage of nearby non-
neoplastic cells, which together form a cancer
niche - These normal cells provide some growth factors
and proteases - Altered motility involves changes in the actin
cytoskeleton
Routes of Metastatic Spread (3)
• Blood
• Lymphatic
• Transcoelomic (pleura, peritoneum)
What are Circulating Tumour Cells (CTCs)?
A rare subset of cells found in the blood of patients with solid tumours, which function as a seed for metastases in the locations in the body
How do cancer cells evade destruction in the circulation?
- Release of coagulation factors, resulting in
formation of an outer platelet shield and then a
tumour platelet microthrombi - This protects from shearing and turbulence forces
- Prevents immune detection using platelet derived
MHC class I coating
What are NK Cells?
They are WBCs, a type of immune cell that has granules (small particles) with enzymes that can self-cells that are presenting abnormal antigens: kill tumour cells or cells infected with a virus
What must Malignant Cells do at secondary sites to form a Clinical Metastasis?
- At a secondary site malignant cells must get
out of a vessel (extravasation) and then grow - This is a dynamic process including adhesion,
vascular migration and endothelial remodelling
(Twist gene)
What are Micrometastases?
- Many malignant cells lodge at secondary sites
- These tiny cell clusters often either die or fail
to grow into clinically detectable tumours - Surviving microscopic deposits that do not grow are
called micrometastases
What is “Tumour Dormancy”?
When a malignant neoplasm relapses years after an apparent cure it is typically due to one or more micrometastases starting to grow
