Cancer Flashcards
What is a tumour?
Any type of mass forming a lesion - does not tell you the cause
May be neoplastic, hamartomatous or inflammatory (e.g. nasal polyps)
What is a neoplasm?
The autonomous (happens regardless of what goes on around it) growth of tissue which which have escaped normal constraints on cell proliferation and growth
exceeds that of normal tissues
Normally growth occurs all the time, but is controlled by specific stimuli and feedback loops
In a neoplasm, however, growth is uncoordinated and persists after the cessation of the stimuli that initiated the change
What are hamartomas?
Localised benign overgrowths of one of more mature cell types e.g. in the lung
Architectural but not cytological disturbance / abnormalities e.g. lung hamartomas are composed of cartilage and bronchial tissue
So, normal tissue present in the normal part of the body, just organised differently (not a cause for worry)
What are heterotopias?
Normal tissue found in parts of the body it normally should not be present e.g. pancreas in the wall of the large intestine
What are the 2 types of neoplasm?
Benign - remain localised
Malignant - invades locally and critically, has the potential and often does spread to other, distant sites (more likely to metastasise)
What is cancer?
A malignant neoplasm
How can you tell the difference between a benign and malignant tumour on an image?
Benign - more clear cut edges, forms away from the tissue
Malignant - infiltrates local tissue, difficult to see when it starts / ends, and where it has spread to
Are all benign tumours ‘good’ and all malignant tumours ‘bad’? (use examples)
No
Some malignant tumours do not kill - invade local tissue but do not spread very easily e.g. skin cancers (squamous cell cancers, basal cell cancers)
Some benign tumours kill - almost always due to location, inaccessible for surgical removal e.g. brain tumours
How are neoplasms classified? (2 descriptions)
Primarily classified based on the cell origin (on the principle that cancer arises from a normal cell counterpart)
Secondly classified as benign or malignant
What are the suffixes to differentiate the naming between a benign and malignant tumour?
Benign: ‘-oma’
Malignant: Either ‘-sarcoma’ or ‘-carcinoma’
How to differentiate between a ‘-sarcoma’ and ‘-carcinoma’?
‘-sarcoma’:
Stromal tumours - (soft) tissue around the cancer cells which consists of connective tissue, blood vessels, macrophages, lymphocytes - it’s a supportive system for the cancer cells
More likely to spread via lymphatics
‘-carcinoma’:
Parenchymal tumours - the cancer cells that have been transformed
More likely to spread via blood vessels
What are some common exceptions of the naming rules?
Ending in '-oma' but being malignant: Some teratomas Hepatoma (liver cell cancer) Lymphoma Melanoma Malignant tumour of the bone marrow - leukemia
For example, how would you name a benign or malignant tumour of the cartilage?
‘chondro-‘ = cartilage
Therefore, chondroma (benign) or chondrosarcoma (malignant)
What are teratomas?
A rare type of tumour composed of tissues not normally present at the site
Can be anything (benign or malignant)
Derives from germ cell and contain tissues from all 3 germ cell layers (endo, meso and ectoderm)
Can be mature tissues or immature (fetal) tissues
e.g. common in the ovaries - tumours often have hair, teeth and bone
What are the 4 main differences between benign and malignant neoplasms?
- Differences in differentiation - malignant tumours show anaplasia, benign tumour cells are relatively well differentiated
A well differentiated tumour is one where we can recognise which tissue it came from - Rate of Growth - benign tumours are slower growing than malignant tumours
- Local Invasion - benign tumours don’t tend to infiltrate the basal lamina, malignant tumours infiltrate the basal lamina
- Metastasis - benign tumours don’t metastasise
Define invasion:
Direct extension into the adjacent connective tissue and /or other structures e.g. blood vessels
What is dysplasia?
Abnormal cells within a tissue, perhaps a stage preceding to cancer (pre-malignant)
What is the major difference between dysplasia and cancer?
There is no invasion in dysplasia, but local invasion of the basement membrane in cancer
What is metastasis?
Spread via blood vessels to other parts of the body
All malignant tumours have the capacity to metastasise, although they may be diagnosed before they have done so
Which blood vessels are cancers more likely to spread through and why?
Veins because arteries have thick walls with lots of muscle and elastin which makes it more difficult to infiltrate
How can cancer spread via body cavities (transcoelomic) and/or direct extention?
By the tumour extending through the pleural cavities/pericardium/peritoneum and maybe even the subarachnoid space, e.g. ovarian tumours commonly metastasise to the liver via the peritoneal cavity
The tumour extends directly through tissue, not via the blood or lymphatics - e.g. from the gallbladder to the liver
Define differentiation when referring to neoplasms (and the structures of malignant tumour differentiated cells):
How much 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 meant by growth pattern?
The architecture of the tumour compared to the architecture of the tissue it is derived from
Tumours have less well defined architecture than the tissue they are derived from
Generally, the more abnormalities in the structure, the more malignant the tumour
What is the process of benign tumours becoming malignant?
Hyperproliferation, causing small bump (but more or less normal)
Increase in cells leads to dysplasia e.g. polyps
Severe dysplasia - more nuclear abnormalities (precancerous as it has not yet invaded the basement membrane)
Cancer - abnormal cell growth invades basement membrane
Invasive cancer / metastasis - invades blood vessels
