Cancer Flashcards
What is a tumour?
Any kind of mass forming lesion. May be neoplastic, hamartomatous or inflammatory (e.g. nasal polyps).
What is a neoplasm?
The autonomous growth of tissue which have escaped normal constraints on cell proliferation.
What can neoplasms be?
Benign (remin localised)
Malignant (invade locally and/or spread to distant sites)
What are cancers?
malignant neoplasms
What do many malignant tumours do?
Many malignant tumours rarely cause death (especially skin cancer) and that some benign tumour do kill (usually because of their location e.g. the brain)
What are hamartomas?
-Localised benign overgrowths of one or more mature cell types e.g. in the lung
-Represent architectural but not cytological abnormalities
E.G lung hamartomas composed of cartilage and bronchial tissue
What are heterotopias?
-Normal tissue found in parts of body where not normally present
E.G. pancreases in wall of large intestine
How do you classify neoplasms?
-Primary description of neoplasms based on cell origin and secondary is whether benign or malignant
E.G tumours of cartilage are either chondromas (if benign) and chondrosarcomas (if malignant)
-The “chondro” stem means derived from cartilage the suffix “oma” means a benign tumour and the suffix ”sarcoma” means a malignant (soft tissue) tumour.
What are teratomas?
- Tumours derived from germ cells and can contain tissue derived from all three for 3 germ cell layers
- May contain mature and/or mature tissue and even cancers (pic from ovary - cystic lesion, hair and teeth)
What are malignant tumours with suffix ‘oma’?
(Malignant) Lymphoma
(Malignant) Melanoma
Hepatoma (better called liver cell cancer)
Teratoma (not all, see above)
What are differences between benign and malignant tumours?
- Invasion
- Metastasis
- Differentiation
- Growth pattern
What is invasion?
This means direct extension into the adjacent connective tissue and /or other structures e.g. blood vessels. This is what distinguishes dysplasia/carcinoma in situ from cancer.
What is metastasis?
This means spread via blood vessels etc (see below) to other parts of the body.
NB: All malignant tumours have the capacity to metastasise although they may be diagnosed before they have done so
What is differentiation?
- This means how much do the cells of the tumour resemble the cells of the tissue it is derived from.
- Tumour cells tend to have larger nuclei (and hence a higher nuclear-cytoplasmic ratio) and more mitoses than the normal tissue they are derived from.
- They may have abnormal mitoses (e.g. tripolar) and marked nuclear pleomorphism (variability in nuclear size and shape).
What is growth pattern?
- This means how much does the architecture of the tumour resembles the architecture of the tissue it is derived from.
- Tumours have less well defined architecture than the tissue they are derived from.
What are the possible routes that tumours spread by?
- Direct extension.
- Haematogenous.
- Lymphatic
- Transcoelomic
- Perineural
What is direct extension?
- This is associated with a stromal response to the tumour.
- This includes fibroblastic proliferation (“ a desmoplastic response”), vascular proliferation (angiogenesis) and an immune response.
What is haematogenous?
- This is via blood vessels.
- The blood vessels usually invaded are the venules and capillaries because they have thinner walls.
- Most sarcomas metastasise first via the blood vessels.
What is lymphatic spread?
- This is via lymphatics to lymph nodes and beyond.
- The pattern of spread is dictated by the normal lymphatic drainage of the organ in question.
- Most epithelial cancers metastasise first via the lymphatics.
What is transcoelomic spread?
- This is via seeding of body cavities.
- The commonest examples are the pleural cavities (for intrathoracic cancers) and the peritoneal cavities (for intra-abdominal cancers)
What is perineural spread?
- This is via nerves.
- This is an underappreciated route of cancer spread
How do you assess tumour spread?
Clinically
Radiologically
Pathologically
How do you describe tumour spread?
T = Tumour: the tumour size or extent of local invasion
N = Nodes: number of lymph nodes involved
M = Metastases: presence of distant metastases
This is called the “TNM” system and the details are different for each kind of cancer
How do you describe grade and stage?
Grade = how differentiated is the tumour (see Differentiation, above)?
Stage = how far as the tumour spread (see TNM above)?
In terms of tumour prognosis, Stage is more important than Grade.
What is grade?
Dependent on the degree of differentiation i.e. how much does the tumour look like the original tissue HIGH grade (looks nothing like original cells) Low grade (looks a lot like original cells)
What is stage?
MOST IMPORTANT determinant of prognosis Considers how far the disease has SPREAD Most commonly used system: TNMTumour: how big is it? Nodes: are lymph nodes involved? Metastases: has it metastasised?
