Sarcomas Flashcards
Sarcoma cell line
- Connective tissue/mesenchymal tumors
How do sarcomas spread?
Blood
What determines sarcoma behavior?
- Tissue of origin
- Grade
What is the most common primary bone tumor in dogs?
- 80% are osteosarcoma
- Others can be fibrosarcoma, chondrosarcoma, hemangiosarcoma
- Rare in cats
Signalment for OSA
- Mid-older age
- Also a peak at 18-24 months
- Large/giant breeds
- Males > females
- Neutered > intact (Rotties)
History for primary bone tumors
- Lameness +/- swelling
Where do OSAs tend to happen on the skeleton?
- Long bones (appendicular) ** most common
75% metaphyseal
- Front legs > back legs
2. Flat bone (axial) - less common; bones of head, ribs, pelvis, vertebrae
Mnemonic for OSA
- Away from the elbow and towards the knee
Diagnosis of OSA in dogs
- Radiographs
- Cytology (preferred; Alk Phos stain)
- Histopathology (gold standard)
DIfferentials for canine OSA on radiograph
- Fungal, bacterial osteomyelitis
- MUST ask about travel histroy
Staging OSA - when to do?
- MOST critical if considering definitive therapy like amputation
- If you’re not going to amputate, the staging you would do will change
Common sites for metastasis for canine OSA
- Lung - MUST examine for staging
- Bone
- LN (poor prognostic indicator)
Diagnosis of lung metastasis for canine OSA
- 3 view lung radiographs (<5% have evidence at outset; met more likely to grow after primary tumor removed)
- CT more sensitive (detects down to 1 mm in size)
If you saw lesions in the chest, would you amputate the osteosarcoma?
- Probably not as good of a candidate for amputation
Bone metastasis diagnosis
- Bone scan or survey bone radiographs
Poor prognostic indicators for canine OSA
- Lung or bone metastasis at outset
- LN metastasis
- Elevated alk phos
- Monocytosis (immune system coercion?)
- Age? (iffy)
Which cell when elevated in peripheral blood is a poor prognostic indicator for canine osteosarcoma?
- Monocytes!
Prognosis if no therapy for canine OSA?
- PAIN
- you cannot do this
- Must have pain control
Prognosis if amputation/no chemo for canine OSA?
3-4 months
Prognosis if radiation for pain control with external beam or radionuclide for canine OSA?
- 4-6 months
- 2 treatments and then come back when they’re painful
- This is reasonable if they don’t want to amputate
Prognosis for just pain meds for canine OSA?
- 4-6 months
- NSAIDs/Opioids
- Would also give bisphosphonates (alendronate; pamidronate; zoledronate)
Aggressive therapy for appendicular tumors and how long?
- Amputation and chemo for 9-12 months
- Cisplatin > Carboplatin (they use this!) > doxorubicin
- They use carboplatin as a single agent
Possible new therapy for OSA (hopefully not important)
- Vaccination against Her-2
Limb sparing osteosarcoma
- Not really sure it’s better
- Big plated leg is a problem
- Still need chemo
- Only works for distal radius
Axial OSA treatment
- Often difficult due to inability to remove surgically (vertebrae, pelvis, etc.)
- Palliative radiation
- Pain meds
- Curative radiation (when spine is involved)
- Local recurrence happens a lot
Survival times for axial tumors when removal is possible and can allow additional chemotherapy (OSA)
- Probably longer than for long bone tumors as metastasis comes slower
- Likely only when in mandible or ribs
How common is feline OSA?
- Rare but happens
- Met comes slower than in dogs
Treatment of choice for feline OSA
- Amputation
- Palliative doesn’t make much sense
Fibrosarcoma in bone prognosis
- Better than OSA
Chondrosarcoma in bone prognosis
- better than OSA unless high grade
Hemangiosarcoma bone tumor prognosis
- As bad as anywhere
Histiocytic bone tumors prognosis?
- Not sure
Plasma cell tumor lymphoma bone tumor prognosis?
- Good?
Where do soft tissue sarcomas arise from?
- All sorts of supportive tissues
- Fibrosarcoma common
- All behave very similarly
What’s possibly more important than type for soft tissue sarcomas?
- Tumor grade!
Signalment for STS
- Usually older, larger dogs
- Any age and breed possible
STS presentation
- Usually a mass, but can arise from internal soft tissues as well
Biologic behavior of STS**
- Locally aggressive
- Invasive
- Poorly defined margins
Metastatic potential of STS
- SLow to metastasize in general
Where do STS metastasize?
- They often spread to lungs more than LNs
- If they spread to LN that’s worse
What is most predictive of prognosis for STS?
- Grade should be predictive
- Mitotic index may be most important prognostic indicator
Grade II vs Grade III STS (mitotic index)
Grade II: 10-19
Grade III: 20+
Diagnosis of STS
- Cytology suggestive
- Incisional biopsy is required for true diagnosis and grade
- Excisional biopsy - be SURE you know your margins!!
Staging for STS: Tumor
- Tumor measurement may require imaging
- Radiographs rarely adequate
- Ultrasound helpful
- CT used a lot
- MR
Staging for STS: Lymph nodes
- If they’re big, freak out
- If not, might not matter
Staging for STS: Metastasis
- Thoracic examination
- Radiographs
- CT if high grade or undertaking a life-altering procedure
Surgery for STS
- AGGRESSIVE treatment required
- 3cm in all directions or 5cm in cats
- Submit for histopath or trim to know if you got clean margins
Radiation for STS
- Best for minimal disease (incomplete sx margins)
- Gross tumor may require higher dose
- High dose difficult to achieve in some locations
Chemotherapy for STS
- Can do chemotherapy (gold standard doxorubicin) or metronomic chemotherapy (low dose alkylators plus NSAID)
- Okay if people can’t go for radiation
When is chemo or metronomic chemo best for STS?
- Incomplete margins and owners don’t want to go for radiation
Prognosis and treatment for low grade STS
- Surgery alone can be curative if done properly!
- Surgery with follow-up radiation when margins not adequate
Prognosis and treatment for high grade STS
- High potential for metastasis (40%)
- Surgery +/- radiation +/- chemotherapy
Prognosis and treatment for non-resectable tumors
- Palliative radiation + metronomic therapy
- They shrink a little and may get a little better quality of life
Feline STS - what causes?
- VACCINE associated sarcomas
What is the rule of 1, 2, 3 with feline STS?
- Remove a mass at a vaccine site when:
1. Still growing at 1 month
2. Greater than 2 cm in size
3. Still present at 3 months post vaccination - Same rules apply if due to other injections
Signalment for feline STS
- Any vaccinated cat (they got 2-3 year old cats)
Biologic behavior of feline STS
- Locally extremely aggressive (the most high grade sarcomas)
- 10-25% metastasize
Staging for feline STS
- Advanced imaging nearly ALWAYS required
Surgery for feline STS
- BE careful
- Remove with margins the first time
- 5cm or 2 facial planes required for cure
Radiation for feline STS
- Most helpful as follow-up when margins are clean but <5 cm
What happens if you do a bad surgery for feline STS?
- If the first surgery leaves dirty margins, the cat may have no hope for long-term tumor control
- Bad surgery - prematurely dead cat
Chemotherapy for feline STS
- 10-25% metastasis potential
- Chemo has not been documented to help overall survival but may help shrink the tumor
Electrochemotherapy for feline STS
- Gets chemotherapy into the tumor
Prevention of feline STS
- Decrease use of vaccines, use canary pox adjuvant vaccine
- Never use a killed virus vaccine in a cat which has had a VAS (including family members)
- vaccinate low on limbs or over abdominal fat to facilitate tumor removal
- Don’t vaccinate a cat that has had the problem
