Tumour characteristics Flashcards
What is cancer?
The uncontrolled growth of cells, which can invade and spread to distant sites.
What is a tumour?
An abnormal swelling.
What is a neoplasm?
Lesion resulting from autonomous growth of cells that persists in the absence of the initiating stimulus.
What is histogenesis?
The differentiation of cells into specialised tissues/organs during growth from undifferentiated cells (germ layers).
What is the histogenic classification of tumours that arise from epithelial cells?
Carcinomas.
What is the histogenic classification of tumours that arise from connective tissue?
Sarcomas.
What is the histogenic classification of tumours that arise from lymphoid/haematopoietic organs?
Lymphomas / leukaemias.
What was the epidemiology of cancer worldwide in 2008?
- 7 million new cases.
- 6 million deaths.
-expected to increase
What causes geographical variation in specific cancers? (2)
- Exposure to environmental carcinogens
- Screening programmes
How has the incidence of cancer changed since 1975?
Steady increase in incidence, slower rate now due to awareness/screening.
How has the mortality of cancer changed since 1975?
Overall decrease.
What are the most common cancers in males? (3)
- Prostate
- Lung
- Colon / rectum
What are the most common cancers in females? (3)
- Breast
- Lung
- Colon / rectum
How are tumours characterised? (4)
- Differentiation
- Rate of growth
- Local invasion
- Metastasis
Do malignant tumour tumour grow faster than benign tumours?
Not necessarily - many exceptions.
-rapidly-growing malignant tumours tens to be lethal faster
What is differentiation?
The extent that neoplastic cells resemble normal parenchymal cells.
-both morphologically and functionally
How do benign and malignant tumours differ in terms of differentiation?
- BENIGN - well-differentiated (resemble parenchymal cells), mitoses rare
- MALIGNANT - wide-range of differentiation, most have morphological change
What does morphology mean in terms of tumours?
Shape/structure of cells.
What is aanaplasia?
Poor cellular differentiation, don’t resemble normal.
-usually malignant
What are the main morphological changes that occur in tumours? (4)
- Neoplasm
- Abnormal nuclear morphology
- Mitoses
- Loss of polarity
What is pleomorphism?
Variation in size/shape of cells and their nuclei.
List some examples of abnormal nuclear morphology. (4)
- Nuclei too large for cell
- Variable nuclear shape
- Clumped chromatin distribution
- Hyperchromatin
What is the nuclear to cytoplasmic ratio of most cells?
1: 4 to 1:6.
- can»_space; 1:1 in tumour cells
What is mitoses?
A method of cell division, indication proliferation.
- seen in normal tissues with high turnover rate
- seen in malignancy
What are the abnormal mitotic processes seen in malignancy?
Tripolar, Quadripolar, etc.
What is loss of polarity?
- Orientation of cells disturbed
- Disorganised growth
- nuclei move to bottom
What does well-differentiated mean?
Closely resembles normal tissue of origin.
- little/no anaplasia
- benign (occasionally malignant)
What does poorly differentiated mean?
Little resemblance to normal tissue of origin.
-very anaplastic
What does undifferentiated / anaplastic mean?
Very poor differentiation, cannot be identified by morphology alone.
-molecular techniques required
What is grade a measure of?
How well differentiated a tumour is.
- 1/low = well differentiated
- 3/high - poorly differentiated
What is stage a measure of?
The severity and prognosis of a disease.
What does better differentiation lead to?
Better retention of normal function.
What are the main features of endocrine tumours? (3)
- Benign and well-differentiated
- Often secrete hormones characteristic of origin
- Increased hormone levels can be used for diagnosis
What is local invasion?
When tumours spread to healthy tissue immediately surrounding them.
What are the invasive features of benign tumours? (2)
- Localised to site of origin
- No capacity to infiltrate / invade / metastasise
What are the invasive features of cancerous tumours? (3)
- Infiltration
- Invasion
- Destruction
What is encapsulation in relation to benign tumours?
Rim of compressed fibrous tissue surrounds benign tumours.
-ECM is deposited by stromal cells activated by hypoxia
What is the tissue plane of a benign tumour?
Moveable, easily palpable and easily excised.
-due to capsule
What often surrounds malignant tumours?
Pseudo-encapsulation.
-slow-growing, rows of cells penetrate margin
Why is surgical resection of malignant tumours often difficult?
Often penetrate organ surfaces and invade.
- requires resection of adjacent normal tissue
What is metastasis?
The spread of tumour to sites physically discontinuous with primary tumour.
-indicates malignancy
Do benign tumours metastasise?
No.
What proportion of non-skin malignancies have metastasised at diagnosis?
30%.
What are the general features of tumours that have metastasised? (4)
- Lack of differentiation
- Local invasion
- Rapid growth
- Large size
What are the main pathways for metastasis? (3)
- Direct seeding
- Lymphatic spread
- Haematogenous spread
What are the general features of metastasis due to direct seeding?
Neoplasm penetrates an open field, without physical barriers (e.g. peritoneal cavity, joint spaces).
-can remain confined to surfaces without penetrating
Give an example of a malignancy in the abdomen that spreads via direct seeding?
Pseudomyxoma peritonei.
-often spreads before penetrating bowel wall
What are the main features of lymphatic spread?
- Tumours spread within lymphatic vessels
- Follows route of lymphatic drainage
How does breast cancer spread, and where does it normally spread to first?
Via the lymphatic system.
-axillary nodes first
What is the sentinel node?
The first lymph node that receives flow from the primary tumour.
How are sentinel nodes identified?
Injection of tracers / coloured dyes.
What are regional lymph nodes?
A lymph node that drains lymph from the region around the tumour.
How are regional lymph nodes used to prevent further tumour spread?
Tumour cells stop within regional nodes and can be destroyed by a tumour-specific immune response.
What type of tumour is haematogenous spread more common in?
Sarcomas.
-also seen in carcinomas
What type of blood vessels are more easily penetrated by tumours?
Veins.
-thinner walls
Where do tumour often metastasise to via haematogenous spread?
First encountered capillary bed.
-liver (portal) and lungs (caval) are most common
How does the rate of growth differ between malignant and benign tumours?
Benign tumours tend to be slow-growing, malignant tend to be faster.
-variable
What is a stroma?
Connective tissue framework that neoplastic cells (and organs) are embedded in.
What 3 things does a stroma provide?
- Mechanical support
- Intercellular signalling
- Nutrition
What is a desmoplastic reaction?
Fibrous stroma formation around the tumour due to induction of connective tissue fibroblast proliferation by growth factors.
What do stroma surrounding tumours contain?
- Cancer-associated fibroblasts
- Myofibroblasts
- Blood vessels
- Lymphocytic infiltrate
What are the main types of clinical complications of tumours? (3)
- Local
- Metabolic
- Due to metastases
What are the local clinical complications of tumours?
- Compression (displacement of surrounding structures)
- Destruction (invasion)
What is thyrotoxicosis?
Hyperthyroidism.
-well differentiated, large tumour»_space; increase thyroid hormones
What are non-specific metabolic effects of tumours?
- Cachexia (weight loss)
- Warburg effect
- Neuropathies
- Myopathies
- Venous thrombosis
What is the Warburg effect?
Cancer cells predominantly produce energy by a high rate of glycolysis followed by lactic acid fermentation.
-increased glucose uptake on scan
