oncology 1 Flashcards
cancer staging tells us what? determined by what?
Extent of disease
Determined (mostly) based on
preoperative evaluation
Lymph nodes
Lungs
Other
cancer grading tells us what? requires what and associated with what?
Determination of tumour behaviour
Requires histopathology
CANNOT be determined on cytology
Associated with propensity to spread elsewhere vs. local aggressiveness
how many FNA slides should we make? how deep should we go into the lump?
at least 5 (8-12 not unusual !!!)
2-3 separate collections- different areas
Pass needle through 2/3 of the thickness
how do we avoid blood dilution with FNA?
¡ Don’t use large bore needle
¡ 22-gauge maximum !
¡ Don’t over-aspirate
¡ if you see it, it’s blood
¡ Imprints: blot blood off of tissue first
¡ make it stick
characteristics of round cell tumours
round cell tumours
Lymphoma (LSA), Mast cell tumour (MCT), histiocytoma, plasma cell tumour, melanoma, transmissible venereal tumour (TVT)
Usually exfoliate well
> Solid tissue aspirates usually highly cellular
> Neoplastic cells often are in effusions
Usually can get a specific dx (tumour type)
characteristics of epithelial cell tumours
i.e. Carcinoma
Usually exfoliate well
> Aspirates of solid tissue usually exfoliate well
> +/- in effusions
How specific a diagnosis?
> benign (normal/hyperplastic/adenoma) vs. malignant (carcinoma)
> sometimes specific cell type
mesenchymal tumour characteristics
i.e. Sarcoma
Often exfoliate poorly
> solid tissue aspirate may be acellular
>virtually never exfoliate in effusions
-usually need histology to determine exact tumour type
pros and cons of biopsy
PROS
-better planning
-definitive Dx enables pre-op radiation
CONS
-two procedures
>progression while waiting to do definitive sx
-increased risk of local recurrence
when to biopsy
If you cannot get a definitive answer from cytology alone
If the grade of the tumour would affect the treatment elected
>esp in areas where wide surgical margin will be hard to obtain
when not to biopsy
If you can get a definitive answer off cytology alone (eg: MCT) and surgical approach would not be affected by histopathology
If you are unsure of surgical approach and biopsy may compromise curative intent procedure
incisional vs excisional biopsy definitions
incisional - take a piece of the tumour to get a diagnosis
excisional - remove the entire tumour with a narrow margin of normal tissue (leave fascial plane intact)
advantages and limitations of incisional biopsy
Advantages:
> Won’t change definitive surgical margins
> Doesn’t decrease the chance of a clean cut (if taken properly!)
Limitations:
> Second surgery required in all instances (including benign disease)
advantages and limitations of excisional biopsy
Advantages:
> potentially curative with benign
disease
Limitations:
> Increases re-cut margin if malignant
> Can decrease chances of clean cut
- First cut is always likeliest cure!
should we typically do incsional or excisional biopsies? when is each appropriate? what should we do first in either case?
INCISIONAL biopsy should be performed rather
than excisional biopsy in all cases, except:
> Very small cutaneous masses <1cm
> Unable to get larger margin regardless of surgery (e.g. splenectomy)
Should NOT be performed without cytology first (particularly when excisional)
methods for an incisional biopsy
Wedge/ Keyes punch
Core/Tru-cut needle biopsy
methods for an excisional biopsy
Surgical excision
Keyes punch
what is a Wedge/Keyes Punch? how do we take the biopsy? benefits and limitations?
Take at the centre (avoid necrosis) NOT
periphery
Benefit: Large samples
Limitation: Generally requires anesthesia
Biopsy tract needs to be taken at definitive surgery
Can be used for incisional biopsy (in the centre of the mass)
OR
Excisional biopsy (for very small lesions)
what is a core/tru-cut needle biopsy? where do we use it? benefits and drawbacks?
Core/Tru-cut Needle Biopsy
Large tumours that would be difficult to get deep enough to obtain a sample
Benefit: Can be done under sedation
Limitation: Small samples
do properly performed biopsies increase the likelihood of future metastasis?
no
current therapies for cancer treatment in pets
Surgery
Radiation therapy
Chemotherapy
Investigational
surgical considerations for tumour removal
Minimize the handling of the tumour
Ligate the venous side first
Change gloves, instruments & towels
Lavage
what happens after excision that makes the defect appear larger?
tissues will retract
current treatment therapies for cancer in pets
Surgery
Radiation therapy
Chemotherapy
Investigational
what simple tool can help you plan a surgical excision?
sterile marker
anatomy of a tumour from outsde in
-normal tissue (eg. muscle) > may contain skip metastasis
-reactive zone > may contain satellite tumours
-pseudocapsule
-tumour
what is the pseudocapsule?
compressed neoplastic cells encapsulating the tumour
what is the reactive zone?
reactive host cells surrounding the tumour
what is a satellite tumour?
neoplastic cells outside the pseudocapsule
what is a skip metastasis?
rare. Neoplastic cells distant to the tumour (in the same compartment)
types of surgical excisions. which have curative intent?
-intracapsular
-marginal
curative intent:
-wide
-radical
what is an intracapsular excision? when should it be performed?
No margins
Should only ever be performed with benign disease
Leaving gross disease behind
> Lipoma
> Bone cyst
what is a marginal excision? when should it be performed?
Minimal margins
Leaving microscopic disease behind
> Benign tumours
> certain locations
-take out pseudocapsule
what is a wide excision? when do we do it?
Curative intent
Does not address skip metastases
-take out reactive zone
what margins do we need to consider with a surgical tumour excision?
both deep and lateral
how do we define our margins for a wide surgical excision?
Lateral Margins
Metric
Based on distance from the peripheral edge of the tumour
Typically 1-3cm depending on the tumour type
Skin incision first
Then extend deep and evenly (as if you are
coring an apple!) until you reach the fascial plane
Continue incision at same margin through the fascial plane
in terms of tumour excisions, what is a fascial plane?
Deep margin
Barrier to tumour penetration
“sheaths, sheets or other dissectible connective tissue aggregations visible to the unaided eye”Wendell-Smith 1997
Tumour should be moveable above it
Lack of fascial plane is most common reason for a“dirty margin”
practically, what is a fascial plane made of?
Barrier to tumour invasion
Practically…
Fascia
Tendon/ligament
Muscle
Bone
what do available fascial planes vary with?
-location
>distal limbs have limited fascial planes
>junction of fascial planes can be challenging
what type of incision can improve cosmesis? what are drawbacks?
Elliptical excision may improve cosmesis
> Beneficial in instances of palliation
HOWEVER
> Extends cancer field
> Not recommended for malignant lesions
to drain or not to drain, after tumour excision?
Seroma/hematoma can disperse residual tumour cells
HOWEVER – use of drains increases the cancer field
> AVOID if possible
> If necessary locate in area that can be easily resected or included in RT field
what is a radical excision?
Removes entire compartment
Prevents any chance of local recurrence
> Amputation
> Splenectomy
> Lung lobectomy
what should we do with excised tumours?
ALL TUMOURS SHOULD BE SUBMITTED OR SAVED
Submit the whole thing, not just a piece
Submit samples in formalin 10:1
If the sample is too large for formalin- call your lab for advice
when submitting a sample, what should we include? how should we prepare it?
Concise, accurate history
Maintain proper orientation of tissue:
> Provide a drawing
> Place a suture on a specified margin
Ink your lateral and deep margins
Do not incise the surgical margin
Fixative incisions “bread-loafing” through tumour boundaries that will not confuse the pathologist
how to ink your sample
Typically 2 colours
> Lateral margins
> Deep margin
Best to ink your deep margin directly below the tumour
what is a clean vs dirty excision?
clean - no tumour cells contact the margins
dirty - tumour cells contact the margins
