oncology 2 Flashcards
(31 cards)
Ddx Bone Tumour
- Osteosarcoma (85‐90%)
- Fungal osteomyelitis
- Hemangiosarcoma
- Metastastic tumour
- Chondrosarcoma
- Histocytic Sarcoma
- Multiple myeloma
- Fibrosarcoma
Most common primary bone tumour
in dogs and cats?
osteosarcoma
are osteosarcomas more common in dogs or cats?
dogs
what % of bone tumors in dogs are osteosarcoma? what types of bones does it generally affect?
- > 85% of bone tumours in dogs
- 80% of osteosarcoma affects the long bones or appendicular skeleton
osteosarcoma signalment - breeds, age?
*Large and Giant Breeds
Age:
*Median age 7 years
*Two “peaks” in age at presentation
> 18‐24 months
> 7‐9 years
osteosarcoma presentation - what might we see?
- mild or severe
- acute or chronic
- some response to analgesics / rest
- pathologic fracture
- soft tissue swelling
common sites for osteosarcoma
- Metaphyseal region
() - Common sites:
- Radius ‐ Distal
- Humerus ‐ Proximal
- femur - distal
- Tibia – Distal or Proximal
- “Away from the elbow and towards the knee”
diagnostic approaches ;/ tools for osteosarcoma
- Signalment & History
- Physical & Orthopedic exam
- radiographic signs
- Cytology/Histopathology
radiographic signs of osteosarcoma
- cortical lysis
- extension into soft tissue
- lack of distinct border between normal and abnormal
- does not cross joint
osteosarcoma - to biopsy or not? what to do?
- Usually not necessary
- Fine needle aspirate quite sensitive
- Jamshidi/ Michelle trephine
- Clinician’s preference
- Atypical signalment, location or
radiographic appearance - Diagnosis will change treatment plan
is fna good for osteosarcoma diagnosis? is fracture an issue with this?
- Bone FNA has a 95% accuracy for diagnosis of OSA
- Can often get answer of soft tissue component
- Low risk of fracture
Risks of Bone Biopsy for animal
- increased lameness post biopsy
> can be due to pathologic fracture - contamination of biopsy tract
- increased fracture risk for RT
if we do a bone biopsy for osteosarcoma, how do we interpret the findings? how should we take the biopsy?
- non-diagnostic sample
- Reactive bone does NOT = benign disease
Risks of Bone Biopsy - biopsy through the center of the radiographic lesion
Where is it… how do we answer this question for osteosarcoma?
staging
when we stage osteosarcoma, what do we commonly see? what is the purpose of staging?
- > 90% cases have micrometastasis at the time of diagnosis
- Staging is done to determine if there is evidence of gross metastasis
- Where?
- Lungs
- Bone
- Lymph nodes
how to take radiographs to check for osteosarcoma metastasis
three-view thoracic radiographs - lungs
how common is metastasis to bone in osteosarcoma? how can we detect this?
- ~10% of dogs will have metastasis to the bone
- Orthopedic examination
- Survey radiography
- nuclear Scintigraphy (bone scan)
how common is metastasis to the lymph nodes in a case of osteosarcoma? what does this mean? how can we check?
- 4% metastatic rate
- Significantly shorter survival times
- FNA of enlarged regional lymph nodes
- Histopathology of lymph nodes with amputation
what is the purpose of bloodwork in a case of osteosarcoma? what are we looking for?
- Assess overall health of patient
> CBC, serum biochemistry, urinalysis - ALP
> bone isoenzyme (bALP)
> prognostic indicator - renal status
prognosis for osteosarcoma, if no gross metastasis at diagnosis (median survival time) for different treatment options
- aputation, chemo, palliative, pain mgmt
If no gross metastasis at diagnosis:
- Amputation + chemotherapy: MST 10‐12 months
- Amputation alone: MST 4-6 months
- Palliative RT +/‐ BP: MST 4 months
- Pain management: MST weeks‐months
what can we do about osteosarcoma?
local and systemic treatment modalities
local:
- surgery
- radiation
systemic:
- chemotherapy
- adjunctive therapy
- immunotherapy
what is the purpose of local therapy for osteosarcoma? what options do we have? what must we keep in mind?
- local therapy = palliative
> amputation vs limbsparing options - metastatic disease in >90%
what characteristics of dogs and owners make them limb-sparing candidates for osteosarcoma treatment?
dogs:
- distal radius most common site
- minimal soft tissue involvement
- <50% of the length of the bone affected radiographically
owners:
- educated
- committed; $$, time
- resilient, reasonable
limb-sparing osteosarcoma treatment options
- surgical limb sparing
- stereotactic radiosurgery +/- surgery
