5.4.3: Oncology Flashcards
Grade
features of a tumour on cytology/histopathology which allow predictions to be made about the tumour’s behaviour.
Stage
an assessment that combines features of the primary tumour and a measurement of where it has spread.
What groups can we put tumours in and how does this help us?
Group tumours as one of the following - this allows us to predict how the tumour will behave: how it will metastasise and how to approach treatment. The more neoplastic the cells become, the more undifferentiated they will become.
* Epithelial cell
* Mesenchymal: tumours of connective tissue and bone
* Round cell: all cells of the immune system
Characteristics of epithelial cell tumours
- Tend to be locally invasive with peritumoural inflammation
- Tend to metastasise later on
- Tend to require less complicated surgical removal
- Can respond to chemo but often don’t so surgery is required
Examples of epithelial cell tumours
- Papilloma
- Squamous cell carcinoma
- Transitional cell carcinoma a.k.a. urothelial cell carcinoma
- Adenoma (often small unproblematic skin lumps)
- Adenocarcinoma
Characteristics of mesenchymal cell tumours
- Mesenchymal = tumours of connective tissue and bone
- More metastatic -> spread through blood vessels much quicker than epithelial
- More locally invasive
- Can respond to chemo but often don’t -> surgery is required
Examples of mesenchymal cell tumours
- Fibroma/ fibrosarcoma
- Osteoma/ osteosarcoma
- Haemangioma/ haemangiosarcoma
- Lipoma/ liposarcoma
- Chondroma/ chondrosarcoma
Characteristics of round cell tumours
- Large group that covers all cells of the immune system
- This group responds well to chemo
Examples of round cell tumours
- Lymphoma
- Mast cell tumour
- Plasma cell tumour
- Histiocytic sarcoma
How do sarcomas metastasise?
Via blood
How do carcinomas metastasise?
Via lymphatics
How do melanomas metastasise?
Random metastasis - however they want (via blood or lymphatics)
How do mesenchymal cell tumours metastasise?
Via lymphatics
How do epithelial tumours metastasise?
Via blood
How do round cell tumours metastasise?
- The immune system is in many areas of the body all the time
- MCTs tend to spread with lymphatics, so are often seen in the LNs
- All other round cell tumours tend to spread systemically: the liver and spleen are lymphoid organs so common sites for metastases
If a tumour spreads by blood, where are metastases likely to end up?
- Look at organs with small vessels where the tumour cells will get stuck
- e.g. lungs, liver, or very fine vascular systems in the paw pads of cats
Chemo ± surgery is the treatment plan for which type of tumour?
Round cell tumour
Surgery ± chemo is the treatment plan for which type of tumour?
Epithelial cell tumour
Mesenchymal cell tumour
What are your diagnostic options for a mass? What are the pros and cons for each?
- FNA
✅ Easy, can be done conscious
❌ May get non-diagnostic sample if tumour cells very tightly bonded to one another
❌ May not be able to reach definitive diagnosis - only gives you cytology results - Incisional biopsy
✅ Can look at cellular architecture
✅ Histopathology can give definitive diagnosis
❌ Requires heavy sedation/ short GA - Excisional biopsy
✅ Aims to remove the mass
✅ Can send for histopathology and get definitive diagnosis
❌ Requires GA
❌ In practice, leave tumour cell extensions behind
What should should remember to do if doing an excisional biopsy of a mass?
- Take a picture before, during, and after the op to show your oncologist
- This allows revision surgery, radiation etc. once definitive diagnosis has been reached and we know more about the tumour
When do you have the best chance of success with regards to removing a tumour entirely?
- At the first surgery
- Thereafter cancerous cells have been moved away from their original position so are much harder to relocate and remove
True/false: it is a good idea to biopsy a thyroid carcinoma, or better still, take a biopsy.
False
They will bleed life-threateningly
True/false: with an osteosarcoma, if you remove the primary tumour, the metastases, if present, will worsen more rapidly.
True
This must be balanced with patient welfare (often bone pain is the most significant welfare concern and taking a leg off might benefit the patient)
Features of a higher grade tumour
- Higher mitotic count
- Nuclear/ cellular atypia
- Poorly differentiated
- Necrosis: tumours need blood supply -> the faster growing will quickly outstrip their blood supply and get necrotic fast
- Locally invasive
