Soft Tissue Sarcoma & Osteosarcoma Flashcards
What do soft tissue sarcomas arise from?
connective tissue, muscle, nerves, fat —> common origin = same treatment/prognosis
- fibrosarcoma
- nerve sheath tumors
- rhabdomyosarcoma
- leiomyosarcoma
- liposarcoma
(spindle cell sarcomas!)
How do canine soft tissue sarcomas act?
- locally invasive and grow by path of least resistance
- low metastatic potential based on grade of tumor
What is the most common presentation of canine soft tissue sarcomas?
firm SQ mass that is movable or fixed in place - not as soft as lipomas!
- generally not painful
What are the 2 major ways of diagnosing canine soft tissue sarcomas? How do they compare?
- FNA of mass - sarcomas not commonly exfoliative, minimal characteristics of malignancy found
- biopsy of mass - more definitive answer, assesses tumor grade
What 2 diagnostics are used to stage canine soft tissue sarcomas?
- CBC/chem/UA = typically WNL
- 3-view thoracic rads = metastasis to lungs due to spread in blood vessels, not lymphatics (no metastasis common at Grades 1-2)
What is considered the best treatment of canine soft tissue sarcoma?
surgery with wide and deep margins
- Grade 3 - may not be curative
- low grade sarcomas do not commonly grow back
When is radiation therapy used for canine soft tissue sarcomas? What are the 2 options?
when resection is incomplete
- DEFINITIVE - finely-fractionated post-surgery or stereotactic with gross disease
- PALLIATIVE - slow growth of tumors, painful masses
What are the 2 options of systemic therapy used for canine soft tissue sarcoma?
- CHEMO - Carboplatin or Doxorubicin for grade 3 tumors or post-surgery (not as helpful for gross disease)
- METRONOMIC - gross disease with incomplete resection
What is prognosis of canine soft tissue sarcoma like?
- long-term tumor control with complete resection - ~100% for Grades 1-2; 50% for Grade 3
- long-term control with incomplete resection + radiation = 75%
metastasis is slow —> MST = 1 year for high grade tumors
What kind of soft tissue sarcoma is common in cats? What kind of sarcoma is this? What is thought to cause this?
injection site sarcoma (vaccine-associated sarcoma) —> spontaneous uncommon
fibrosarcoma (may be OSA or chondrosarcoma)
adjuvant in radies and FeLV vaccines —> now use non-adjuvanted vaccines
Other than a vaccine, what can injection site sarcoma be associated with?
other repeated injections, like Program, Depo-Medrol, or antibiotics due to aberrant inflammatory response
How has administration of vaccines in cats been changed with the occurrence of ISS?
aim to more distal aspects of limbs and tails
- allows for amputation
What is the most common presentation of injection site sarcoma?
cat with a firm SQ mass fixed into place between the scapula or distal limb
- can be painful or uncomfortable
What are the 2 main options for diagnosing ISS?
- FNA - exfoliates better, malignant mesenchymal cells with nuclei of different sizes
- biopsy - incisional based on invasiveness of mass, can see inflammatory cells in tissues or adjuvant within macrophages
How are CBC/chem/UA, thoracic radiographs, and abdominal ultrasounds used to stage ISS?
usually WNL, possible neutrophilia and mild anemia
lungs most common place for metastasis
occasional metastasis to abdominal viscera
What is the purpose of performing a CT scan on a suspected ISS?
- observe the extent of tumor for surgical planning (more invasive than it appears!)
- search thorax and abdomen for metastasis
How is surgery used for treating ISS?
difficult to achieve wide margin in the interscapular space, preferred amputation for limb/tail masses
How is radiation used for ISS treatment?
- DEFINITIVE - always indicated for interscapular masses given the invasiveness of the tumor, still difficult to control
- PALLIATIVE
What systemic therapy is used to treat ISS?
- CHEMO - Carboplatin, Doxorubicin, CCNU* (not as effective for gross disease)
- METRONOMIC - not as commonly done in cats, unknown effectiveness
What is prognosis of ISS like?
tends to grow back around the surgery scar regardless of therapy given, but MST of 18 months with surgery, radiation, and chemo
What is osteosarcoma? What does it typically involve?
primary bone tumor arising from osteoblasts
long bones —> away from the elbow, towards the knee = distal radius most common
How does osteosarcoma act? In what animals is this most common?
high metastatic rate, less metastasis to flat bones and axial skeleton
large/giant breed dogs
What is the typical presentation of osteosarcoma?
- acute/slowly progressive lameness with transient/variable response to empiric pain meds
- hard, painful mass in typical tumor location
- pathologic fracture
What 3 diagnostics are preferred for osteosarcoma?
- radiograph of tumor site - bone lysis, moth eaten or sunburst pattern, pathologic fracture
- FNA - possible due to weakness of bone affected by tumor, sarcoma cells seen
- biopsy - Jamshidi tool
Why is a biopsy not always diagnostic for osteosarcoma?
normal callous often surrounds the tumor
What are some signs on CBC/chem/UA of osteosarcoma? Thoracic radiographs?
elevated ALP shows a worse prognosis, hypercalcemia due to osteolysis
metastasis to lungs, other bones, or skin
What is the best option for pain control in treating osteosarcoma?
amputation of affected limb +/- palliative radiation (no significant effect on tumor otherwise)
- does NOT prevent metastasis
What is the chemotherapy of choice for osteosarcoma?
Carboplatin (4-6 doses)
What supportive medications can be given to patients with osteosarcoma? Why?
bisphosphnates - Zoledronate, Pamidronate
attach to hydroxyapatite receptors on bone and inhibit osteoclastic bone resorption —> may improve bone density
Is definitive radiation commonly used for treating osteosarcoma?
no - poor response, stereotactic may be better
If clients are unable to afford other methods of pain relief for osteosarcoma, what is recommended?
oral pain meds
- NSAIDs
- Gabapentin
- Tramadol
- Tylenol/Codeine
How is metronomic therapy used for osteosarcoma?
can be used in place of chemotherapy or as maintenance therapy after chemo is complete
- unclear effect on survival
What is the prognosis of osteosarcoma like depending on treatment?
- amputation alone = 3-5 months
- amputation + carboplatin = 12 months
- palliative radiation + carboplatin = 7-8 months
risk pathologic fracture if not amputated
How does osteosarcoma compare in cats? How does this affect treatment?
similar to dogs, but there is a very low metastatic potention
amputation is often curative - chemotherapy not commonly given
