Cancer Flashcards
Define tumour
Any kind of mass forming lesion
May be neoplastic, hamartomatous or inflammatory (e.g. nasal polyps)
Define neoplasm
The autonomous growth of tissue which has escaped normal constraints on cell proliferation
It can either be benign (remain localised) or malignant (invade locally and/or spread to distant sites)
Define cancer
Malignant neoplasms
Define metastasis
Spread via blood vessels to other parts of the body
NOTE: all malignant tumours have the capacity to metastasise although they may be diagnosed before they have done so
Define carcinogen
A substance capable of causing cancer
TRUE OR FALSE:
Malignant tumours rarely cause death whereas some benign tumours do
TRUE
Malignant tumours (especially skin cancers) rarely cause death
Some benign tumours do kill (usually because of their location e.g. in the brain)
What are hamartomas?
Localised benign overgrowths of one or more mature cell types (e.g. in the lung)
They represent architectural but not cytological abnormalities
E.g. lung hamartomas are composed of cartilage and bronchial tissue
I.E. “MALFORMED NORMAL TISSUE”
What are heterotopias?
Normal tissue being found in parts of the body where they are not normally present
E.g. pancreas in the wall of the large intestine
How are neoplasms classified?
Primary description is based on the cell origin
Secondary description is whether it is benign or malignant
E.g. tumours of cartilage are either chondromas (benign) or chondrosarcomas (malignant)
What are teratomas?
Tumours derived from germ cells and can contain tissue derived from all three germ cell layers (mesoderm, ectoderm, endoderm)
May contain mature and/or immature tissue and even cancers
Name features which distinguish benign from malignant tumours
- Invasion
- Metastasis
- Differentiation
- Growth pattern
What is invasion?
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 differentiation?
How much the cells of the tumour resemble the cells of the tissue they are derived from
Tumour cells tend to/may have:
- Larger nuclei (and hence a higher nuclear-cytoplasmic ratio)
- More/abnormal mitoses (e.g. tripolar)
- Marked nuclear pleomorphism (variability in nuclear size and shape)
What is growth pattern?
How much the architecture (how cells are arranged) of the tumour resembles the architecture of the tissue it is derived from
Tumours have less well-defined architecture
TRUE OR FALSE:
Benign tumours may become malignant
TRUE
Name the routes by which neoplasms spread
- Direct extension
- Haematogenous
- Lymphatic
- Transcoelomic
- Perineural
What is direct extension?
Associated with a stromal (connective tissue) response to the tumour
This includes fibroblastic proliferation (“a desmoplasmic response”), vascular proliferation (angiogenesis) and an immune response
What is haemotogenous route?
Via blood vessels
Blood vessels usually invaded are the venules and capillaries because they have thinner walls
Most sarcomas metastasise first via blood vessels
What is the lymphatic route?
Via lymphatics to lymph nodes and beyond
Pattern of spread is dictated by the normal lymphatic drainage of the organ in question
Most epithelial cancers metastasise first via lymphatics
What is the transcoelomic route?
Via seeding of body cavities
The most common examples are pleural cavities (for intrathoracic cancers) and the peritoneal cavities (for intra-abdominal cancers)
What is perineural spread?
Via nerves
Underappreciated route of cancer spread
How is tumour spread assessed?
- Clinically (e.g. palpate axillary nodes)
- Radiologically
- Pathologically
How is tumour spread described?
T = 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
What are the pathological features that may predict prognosis?
- Grade - how differentiated the tumour is (microscope)
- Stage - how far tumour spread (TNM)
TRUE OR FALSE:
In terms of tumour prognosis, grade is more important than stage
FALSE
Stage is more important than grade
