oncology 1 Flashcards
most common cancers for dogs
- mammary
- skin
- connective tissues
- testes
- melanoma & lymphoma tie
most common cancers for cats
- non-hodgkin’s lymphoma
- leukemia
- skin
- mammary
- Connective tissue
how common is cancer as a cause of death for cats and dogs?
- 47% of dogs
- 32% of cats
causes of cancer
environment (up to 80‐90% of human cancers)
diet
chemicals (hormones)
radiation
oncogenic viruses
> feline leukemia virus
> human papilloma virus
- genetic factors
- trauma
why is there an increasing prevalence of cancer in companion animals?
Due to increased life expectancy of pets (increased risk with age)
a) better nutrition
b) vaccination for infectious disease
c) preventative medicine
d) leash laws
e) human‐animal bond
Treatment of Cancer requires knowledge of :
- Biology of the disease/natural history of the tumour
- How to diagnose & stage
- Modalities of treatment
- Costs
- Expectations/prognosis
- Client Education
what type of Knowledge of the Biology / Natural History of the Tumour should we know for treatment plans?
- Common sites
- Malignancy potential
- Where to look for metastatic disease
- Distant effects (paraneoplastic disorders)
- Precancerous conditions
- Suggests the clinical workup necessary
- Suggests treatment response & prognosis
types of cancer, categorically
*Carcinoma
*Sarcoma
*Round cells
> Lymphoma, leukemia, MCT, ….
clinical presentations / classifications of cancer based on location and spread (stage)
*Local / regional
- local and systemic
*Systemic
are soft tissue sarcomas local or systemic?
local
4 questions of oncology
- what is it?
- where is it?
- how bad is it?
- what to do about it?
the cornerstone of cancer diagnosis - what is it?
biopsy
types of biopsy, and what type they are
- fine needle aspirate (FNA): cytology
- incisional: histology
- excisional: histology
how to interpret biopsy results - what info do we need from pathologist?
- neoplastic versus not neoplastic
> e.g. inflammatory - malignant versus benign
The clinician has the right and the obligation to question the diagnosis if it is inconsistent with the clinical picture !!!
evaluation of malignant criteria all boils down to…
uniform or variable?
soft tissue sarcomas often present as what? diagnostic challenges?
- One of the challenges can be associated with getting a diagnosis!
- Often present as a subcutaneous mass that is slow growing
- Less aggressive tumours are harder to diagnose - Can appear as anything
> Soft and mobile
> Firm and fixed
where on the body do we commonly see STS? what can we mistake them for? best chance for cure?
- Very commonly seen on the limbs
- easy to mistake for a lipoma on aspirate
- Treat early (small) for best chance of cure
- Lipomas are RARE on limbs
how to diagnose STS - what is the use of FNA? do STSs exfoliate well? what can we learn?
- Fine needle aspirate & cytology
- Often exfoliate poorly
- malignant tumours exfoliate better (i.e. diagnosis on cytology can mean a worse tumour)
- Ddx: sarcoma vs scar tissue (spindle
cells)!
Is a FNA useful for diangosing MCT? lipoma? STS?
- good for MCT
- ok for lipoma
- generally poor for STS
use of FNA & cytology for learning about behaviour, stage, and grade?
- cytology can hint at behaviour but does not provide a grade!
- can help direct your preoperative staging
STS Diagnosis: Incisional biopsy
- what is the goal? what technique should we use? considerations for surgery?
- Goal: to achieve a diagnosis with minimal disruption of the mass
> Provides more information about tumour behaviour (grade!)
> Not necessary if diagnosis achieved from cytology - Want the smallest incision possible to get a diagnosis, stay within the boundaries of the mass
> Make sure to go through the pseudocapsule … sarcoma tissue looks a bit like toothpaste!
> Go deep to get through the pseudocapsule but DO NOT disrupt the fascial plane - Plan biopsy based on surgery … must remove biopsy tract later
- (Rarely used for mast cell tumour [MCT])
STS Diagnosis: Excisional Biopsy
- goal? what we learn? when would we use this technique? when is this not reccomended? what are the risks? technique?
- Goal: confirmation of diagnosis when potentially a benign disease process
> eg. granuloma - provides histopathology and grade
- Not recommended if STS highly suspected
- Major risk that you will disrupted local tissues making curative excision more difficult/ not possible
- Occasionally performed for very small cutaneous masses if suspect benign (<1cm) > do not disrupt the fascial plane
Types of STS
- Hemangiopericytoma** (NOT hemangiosarcoma)
- Fibrosarcoma
- Neurofibrosarcoma (peripheral nerve sheath tumour)
- Liposarcoma
- Rhabdomyosarcoma
- Undifferentiated (anaplastic) sarcoma
- others
basis of answering the question: where is it?
staging
clinical staging of tumours tells us what?
- defines the extent of the disease
- Aids in planning treatment
- Allows more accurate prognostication
- Assists in evaluation of therapy
- Allows communication between clinicians
- Nomenclature: ‘TNM’ System (WHO)
staging could require:
- biochemical profile
- urinalysis
- CBC
- thoracic radiographs (3 views)
- abdominal radiographs or ultrasound
- bone marrow aspirate / biopsy
- CT / MRI / PET‐CT / bone scan
- CSF tap
- etc. (FeLV / FIV status)
metastatic risk of sts depends on:
Grade:
- Grade 1: 0‐10%
- Grade 2: 10-20%
- Grade 3: 40-50%
minimum thoracic radiographs to stage STS? When not as useful?
- minimum 2-views thoracic radiographs
> low yield in low grade tumours
> but useful for screening for other disease in older anmals
what type of imaging to consider for staging if high grade?
consider CT thorax
what do we often need for local staging to evaluate the mass & for planning surgery
often need advanced imaging (CT/MRI)
what do we need to konw to answer the question: how bad is it?
Grade
what info does grade tell us about marginal excisions? vs complete excisions?
- Grade is a strong predictor of local recurrence with a marginal excision
- complete excision is a strong predictor of local control
> (ie. clean margins = decreased recurrence)
how quickly will low grade tumors recurr, if they do?
- Often with low grade tumours they can take months‐years to recur
behaviour of STS of Mesenchymal or Connective Tissue Origin
- how locally aggressive? metastatic rate? how to control? how do they tend to metastasize?
- Locally aggressive – somewhat grade dependent
- Distant metastasis depends on grade but overall low metastatic rate
- Grade I: 0-10%
- Grade II: 10-20%
- grade III: 40-50%
- often a surgical disease local control is key
- tend to metastasize hematogenously (ie.lungs)
what treatment modalities can be used for cancer?
- surgery
- radiotherapy
- traditional chemotherapy
- precise therapy
- immunotherapy
treatment modalities for local disease?
- Surgery
- Radiation
treatment modalities for systemic disease?
- Chemotherapy
- Radiation
- immunotherapy
mainstay of STS treatment? other options? what has limited efficacy?
- surgery is the mainstay of treatment
- if surgery alone not possible consider surgery + radiation therapy (RT)
- chemotherapy has limited efficacy
In most cases of cutaneous and SQ masses, what gives us best chance of cure?
surgical excision
Planning for Surgical Excision
> what do we need?
- GET A DIAGNOSIS!
> The diagnosis will significantly affect your surgical approach and therefore it SHOULD be rare to remove a mass without a diagnosis
> Cytology
> Excisional biopsy
> Incisional biopsy
Types of surgical Excisions
- Intracapsular
- Marginal
- Wide
- Radical
what is an intracapsular excision? Goal? pros and cons? limitations?
- aka: intralesional, cytoreduction, debulking
- Goal: decrease the amount of disease present, typically for palliation or lipoma
> residual visible tumour at surgery site - Better to avoid and perform marginal excision whenever possible
- local control is not possible with this technique if malignant disease
> recurrence is a certainty
marginal excision - goal? when is it typically used? follow up?
- aka: excisional biopsy, minimal excision
- Goal: Remove all visible tumour without requiring reconstruction or significant patient morbidity
> Residual microscopic tumour cells at surgery site - Excision with minimal margins, no skin margin or fascial plane
- Typically used in cases where curative intent surgery is not possible and follow up with radiation
wide resection - goal? how do we perform, generally? what do we need for these surgeries?
- aka: Curative intent * Goal: Surgical cure
- Lateral & deep margins (ie fascial plane) to remove complete macroscopic and microscopic tumor
- These surgeries take a lot of planning:
> understanding of anatomy and fascial plane beneath tumor
> may need advanced imaging (MRI, CT)
> may need reconstruction for closure
wide resection technique for STS
- STS: aiming for 3 cm margins + 1 fascial plane deep
> may not always be possible on limbs, but in these cases should consider referral for best chance
> may need advanced imaging to determine extent of tumour
wide resection for MCT - how much do we cut / what are our margins?
- MCT: Proportional margins + 1 fascial plane deep
- if mass <5mm: take 5mm margin + fascial plane
- if mass 5mm - 1cm: take 1cm margin + fascial plane
- if mass 1‐2 cm: take 2cm margin + fascial plane
- if mass >2 cm: take 3cm margin + fascial plane
how do we mark margins for wide excision? what should we plan out? what do we do with deep margin and why?
- Identify margins with sterile marker
- Clip wide and plan any potential reconstruction/ flaps necessary
- Suture deep margin to skin during
excision to avoid shifting of tissues
during formalin fixation
radical resection goal
- Goal: Completely remove the
tumour & surrounding tissue =
no place for recurrence to occur
> amputation
>typically reserved fo cases where cytoreduction not possible
should we always submit a sample of removed tissue? what should we include?
- If it’s worth taking off, it’s worth submitting!
- Always build histopathology into your estimate
- be descriptive
- Make sure your pathologist knows exactly where the sample came from, what was your goal of surgery, & specifically identify any margins you are concerned about
what will histo report tell us?
- Diagnosis and certainty (from pathologist)
- Grade (or why not!)
> mitotic index
> anisokaryosis and other criteria of malignancy
> necrosis - margins
How to interpret margins
- Should be interpreted in light of your surgery
> ie what did you see clinically - all dirty margins are not created equally = did you cut through the tumor or did you think you were cutting clean!
- clean = no tumot cells contact the margins
- dirty = tumor cells contact the margins
- clean but close ??
> pathology recut in areas where < 2mm?
danger of unplanned excision - tumor removal without diagnosis
- danger of disrupting fascial planes, increasing the diameter of the definitive resection, increasing rink that definitive resection will not be successful (curative)
I just did an unplanned excision: What now?
- Advanced imaging for residual tumour
- Scar resection if possible or radiation therapy
- curative intent radiation therapy to scar
- Active surveillance (high chance of local recurrence but could take time depending how HOW dirty)
how is radiation therapy used?
- Increasing availability
- Often combined with other modalities
- control vs cure
use of radiation therapy for STS? pain? price? time? stress?
- Excellent treatment modality for
local control of STS after marginal excision - potentially painful
- expensive
- Time consuming > 4-5 week course of daily fractionated radiation
- stressful for the patient
STS curative methods
- plan for curative intent wide resection with no radiation
OR - plan for a positive margin: marginal excision followed by radiation therapy
STS radiation therapy is best for what type of disease? what are the response rates?
- Microscopic disease is better
- Macroscopic (gross disease)
> 70% response rate for 6-8 months - Microscopic with curative RT
> 85-90% curre - microscopic with palliative RT
> 70% 2-3 years local control
when should we use radiation therapy after STS surgical removal?
- Use in cases of marginal excision, especially if grade II or III
- Another method of local control that can be combined with an
inadequate excision
what is the use of chemotherapy for STS? when is it not reccomended vs recomended? what does it do? schedule optiosn?
- Grade I or II – not recommended
- Grade III – controversial but recommended by some medical oncologists
- systemic treatment of micrometastatic disease
- full course chemotherapy (MTD)
- Metronomic (low dose continuous) chemotherapy
Full course chemotherapy (MTD) drug options
- Doxorubicin
- Mitoxantrone
- Carboplatinum
Metronomic Chemotherapy - reduces or eliminates what? cost? tolerance?
- Reduction or Elimination of the Break Period
> dose reduced accordingly - Low cost, easy to give, well tolerated
> Alkylators: cyclophosphamide, chlorambucil, lomustine (CCNU) - Formal clinical evaluation is currently lacking
metronomic chemotherapy mechanisms
- Direct tumour cell kill
- Angiogenesis
> Indirect
> Direct - Immunologic
- Stromal? Other?
Take home message
Soft tissue sarcoma Diagnosis
- Cytology can be suspicious for STS but not diagnostic
> combined with advance imaging (CT or MRI) can be enough to plan surgery - biopsy is required to make a final diagnosis
> excisional: only if can do another surgery if confirm STS to get clean margins
> incisional: better, as gives diagnosis prior to surgery planning
STS palliative intent treatment
Intralesional or marginal resection +/-
metronomic chemo
STS curative intent - wide or radical
resection not
possible
Marginal excision +RT
STS curative intent, wide or radical resection not possible
Dirty margins:
- RT +/- metronomic chemo
Clean margins
- potential cure, monitor for recurrence
