- What are 2 critical pieces of info to determine to aid decisions regarding treatment and prognosis.
- What are the aims of investigations?
- Type of tumour.
- Spread of tumour.
- Type of tumour.
- Make a histological/cytological diagnosis.
- Determine the extent of local and distant spread.
- Investigate and treat any tumour-related or concurrent complications.
- To determine the patient’s ability to tolerate therapy.
- To determine the overall prognosis.
- Make a histological/cytological diagnosis.
Diagnostic approach to cancer.
- History.
- PE.
- Lab testing.
- Imaging.
- Biomarkers (generally unreliable).
- Biopsy.
– Cytology.
– Histopathology.
Some questions to ask on history taking.
When was the mass first noticed?
Is the patient aware?
Change in appearance?
Any other masses?
Any signs of systemic illness?
– lethargy and exercise intolerance w/ anaemia.
– PUPD w/ hypercalcaemia.
CE.
- Full CE for evidence of metastasis and/or paraneoplastic effects.
- Location.
- Dimensions.
- Character e.g. fluctuant or firm.
- Response to palpation.
- Mobility.
- Margination.
- Available margins.
What does an accurate diagnosis require?
A microscopic examination of representative tissue or cells.
A diagnosis cannot be made upon palpation or diagnostic imaging alone.
- How can cytology samples be collected?
- What info can we gain from cytology samples?
- Touch / impression preparations.
- FNA.
- Cytospins of body fluids / effusions.
- Touch / impression preparations.
- Nature of the tumour (e.g. spindle, vs round, vs epithelial) to help identify cytological features of malignancy.
Advantages of FNA and cytology.
- Quick, cheap, easy, non-invasive.
- In house, may feel comfortable to distinguish inflammatory vs neoplastic lesions.
- In house, can readily differentiate mast cell tumours from lipomas.
- Easy to send these samples away for an expert opinion from a clinical pathologist.
Disadvantages of FNA and cytology.
- Results more likely to be inconclusive than with histopathology.
- There are some risks to consider in approach.
– Can you remove seeded cells along needle tracts in subsequent surgery?
– Degranulation of MCTs (rare).
– Bleeding w/ some types of malignancy is more likely. - Doesn’t allow assessment of tissue architecture and grading of tumours not possible.
- What do histology samples involve?
- Common biopsy collection method.
- Whole pieces of tissue of histopathological examination.
- Punch biopsy.
What does a histology sample allow that a cytology sample does not?
Tumour grading.
Define tumour grading.
The microscopic assessment and quantification of parameters that correlate w/ the clinical aggressiveness of a neoplasm based on the tumour’s architecture.
– invasion of adjacent tissues?
– evidence of metastatic behaviour e.g. presence of neoplastic cells in local blood vessels and/or lymphatics?
Biopsy techniques.
Incisional or excisional.
- Incisional biopsy.
- Excisional biopsy.
- Small incision into area of abnormal tissue and small piece removed.
- Entire lump or suspicious area surgically excised.
- Advantage of incisional biopsy.
- Disadvantage of excisional biopsy.
- Can grade tumour, make definitive diagnosis, assess local aggressiveness prior to surgical planning.
- Taking a gamble as don’t have info yet.
So do not know how much healthy tissue need to leave around tumour in order to remove it in its entirety.
Rules of performing incisional biopsy.
1) Avoid superficial ulceration, inflammation and necrosis.
2) Ensure adequate depth.
3) Try to include a boundary between tumour and normal tissue.
4) Do not predispose to local tumour recurrence or dissemination e.g. via instruments/bleeding.
5) Do not compromise subsequent therapy.
In what circumstance may an excisional biopsy w/o prior incisional biopsy be appropriate?
If knowledge of the tumour type and grade does not change the approach. e.g. bleeding splenic mass (an emergency).
What should be done w/ excised masses?
Should be submitted for histology or fixed and stored in case owners change their mind or the patient deteriorates.
- What is staging of cancer?
- How is staging of cancer useful?
- What does clinical staging consider?
- Extent of neoplastic disease i.e. volume and degree of spread.
- Helps to determine the feasibility of therapy and prognosis.
- Histological grade.
Local invasion.
Metastatic spread.
- What is the most common staging system?
- Outline the aspects of this system.
- Based on WHO “TNM” system.
- T = Tumour – assessing size and invasiveness.
N = Nodes – assessing local draining LNs for evidence of spread.
M = Metastasis – assessing spread to other other organs.
- How do we assess T?
- How do we assess N?
- How do we assess M?
- PE of mass, histopathology, imaging e.g. ultrasound.
- Palpation of LN size and colour, imaging and FNA.
- History, PE, imaging, FNA and bone marrow aspiration (if haematological abnormalities).
- What are the ideal views of inflated chest radiograph to be taken in staging?
- At what size are metastases visible and distinguished from end-on pulmonary vessels on radiograph?
- Ideally 4 views taken.
Left lateral, right lateral, dorsoventral, ventro-dorsal. - > 5mm.
What must the owner be informed about to make the best treatment decision for their pet and them?
- Nature of the disease.
- Treatment options.
- Potential side effects.
- Prognosis with and without treatment.
- Cost.
What are the different aims of treatment?
Cure.
- all cells w/ capacity for tumour regeneration eradicated.
Remission.
- all clinical evidence of cancer disappeared.
- occult cancer cells remain and relapse will occur at some point.
Palliation.
- Reduce pain/improve sense of well-being and/or correct physiological malfunction.
3 main methods of cancer treatments in animals.
Surgical excision.
Radiation.
Anti-cancer / cytotoxic drugs = chemo.
*for systemic cancers, modalities are often combined.
