The behaviour of Tumours Flashcards
whats the difference between benign and malignant
Benign - Slow growing - Well circumscribed borders, encapsulated, spherical and oval - Well differentiated - Low mitotic rate - Non invasive (basement membrane is not breached) - No metastasis - Uniethal - No necrosis Malignat - Rapidly growing - Non encapsulated and irregular shapes - Poorly differentiated - High mitotic rate - Invasive – basement membrane is breached - May metastasise - Lethal - Necrosis; reduces apoptosis
Describe Knudsons two hit hypothesis
- He observed that in inherited retinoblastoma compared to sporadic disease
- Occurred at an earlier age, children often had tumours in both eyes
- Suggested susceptibility he suggested multiple hits necessary to cause cancer
- A mutation in both alleles of a tumour suppressor gene is required as a single functional tumour suppressor gene is usually sufficient for normal function
This can occur in two ways - In sporadic cancer – 2 acquired mutations, 1st hit occurs mutation in one allele and 2nd hit occurs in 2nd allele – tumour grows at a later age as it takes time for both hits to occur
- In hereditary cancer – mutation in one allele already and only 1 hit needed for both alleles to be mutated this is a tumour that occurs at an earlier age
describe the histology of cancer cells
- Lots of cells undergoing cell division
- Centre of tumour can be necrotic
- Shedding or loss of tumour cells from outside
what are the 4 reasons why patients die from cancer
- metastasis
- immunosuppression - Lymphomas and leukaemias
- organ failure - - Tumours cause organs to fail
- haemorrhage - - Infiltration of bone marrows
- secondary malignancies
describe how metastasis kills a patient
- Spreads around the body to many organs. Metastatic diseae occupies vital sites
- Metastatic burden +1kg = death (intracranial tumours is around 100g whether benign or metastatic before death)
what does tumour growth rate depend upon
- doubling time of tumour cells • Doubling time – mitotic rate of tumour • Lengthens as tumour grows • 30 doublings = 1 g (months to years) • 10 more doublings = 1 kg
fraction of tumours are in the replicative pool
• May only be 20% even in rapidly growing tumours
• Tumour stem cells
rate at which tumours are
shed or lost - apoptosis and maturation
extent of differentiation of the tumour
desire be how metastasis occurs
- Undergo Epithelial to Mesenchymal Transitioning
- Breakdown of basement membrane
- Local invasion of ECM
- Tumour cells travel to vascular/lymphatic system and undergo intravasation
- They circulate through the body via lymph/vascular systems and undergo extravasation at a new site
- Undergo Mesenchymal to Epithelial Transitioning
- Micrometastasis forms (only a few cells)
- If micrometastasis cells survive in new environment they form a macrometastasis
- Tumour has spread from one place to another
what do the lymph nodes do
- Drain excess interstitial fluid form the body
how are lymph nodes linked to cancer
- Lymph nodes draining a cancerous organ are likely to drain fluid containing cancerous cells
- Biopsy the sentinel node of a cancer when staging the cancer
- Lymph nodes are surgically removed
What are the two ways that the metastatic cells can move through the body system:
- haematogenous dissemination
- lymphatic dissemination
where does colon cancer, breast cancer and prostate cancer metasise to
- advanved colon carcinoma in the liver
- breast cancer often metastasises to the brain
- metastatic prostate cancer at sites of a new or reactive bone formation site
what is an important component of the TNM staging system
number od nodes
significance of nodal metastasis in therapeutics
- Overall risk of recurrence
- Extent of nodal involvement
- Histological grade and other considerations
- Adjuvant therapy
significance of nodal metastasis
Example: breast cancer.
• A modified radical mastectomy removes the entire breast — including the breast tissue, skin, areola and nipple — and most of the underarm (axillary) lymph nodes which most common site for metastasis. Prevents the cancer from spreading
How do you tell whether a lymph node is infected or not
• Sentinel node biopsy - radioactive tracer and a blue dye are administered near site of tumour. Histological analysis of lymph nodes (sentinel nodes) taking up tracer and dye establish whether cancer is present.
