oncology 1 Flashcards
(45 cards)
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
