Osteosarcoma (objectives only)

Describe the incidence of osteosarcoma in canine patients

- The most common primary bone tumor in dogs (85% of all malignancies in skeleton)

75% of osteosarcomas in dogs are found where?

- Appendicular sites

What are the common appendicular sites of osteosarcoma in canines?

- Distal radius, proximal humerus are more common

- Also seen in proximal and distal femur and tibia

What are common axial sites of osteosarcoma in dogs?

- Mandible (27%)

- Maxilla (22%)

- Spine (15%)

- Cranium (14%)

- Ribs (10%)

- Nasal cavity (9%)

- Pelvis (6%)

You are more likely to see appendicular OSA in large or small breed dogs?

- Large breed

You are more likely to see axial OSA in large or small breed dogs?

- Small breed

Where are extra skeletal OSA found?

- Mammary glands, SQ, spleen

What is the most common site of osteosarcoma metastasis in dogs? What are other sites that are common?

- Lungs*

- Regional lymph nodes, other bones, skin, visceral organs

What region of the bone is more likely to have a secondary/metastatic lesion due to OSA? Why?

- Metaphyseal region of long bones

- Due to the presence of the nutrient foramen

True or False: hypercalcemia is a negative prognostic factor associated with canine osteosarcoma

- False - you will not see hypercalcemia with OSA

What are major progonstic factors?

Age, Weight

Tumor location, histopathologic grade

Tumor stage

Biomarkers (ALP, relative monocytosis, relative lymphocytosis, cholesterol)

Name 4 bloodwork changes that are prognostic factors for canine osteosarcoma. What are these changes associated with in terms of OSA prognosis?

- Relative monocytosis (> 400 cell/uL) - associated with decreased DFI

- Relative lymphocytosis (> 1000 cell/uL) - associated with decreased DFI

- ALP elevations associated with OSA - associated with decreased DFI and OST

- Total cholesterol above reference range seen in about 45% of OSA dogs - elevations associated with better OST

What options for curative intent treatment are available for canine osteosarcoma?

Surgery

- Limb amputation for local disease on the appendicular skeleton

- En bloc resection for local disease on axial skeleton

- Limb sparing surgeries

Stereotactic Radiation Therapy

- Destroy cancer cell's DNA leading to inability to divide - kills normal tissue as well (a map of the 'target' is made to help destroy the cancer cells)

Chemotherapy +/- immunotherapy

- Carboplatin

- Doxorubicin

- Cisplatin

- Doxorubicin-Carboplatin

- Carboplatin-Gemicitabine

What options for palliative treatment are available for canine osteosarcoma?

- Surgery/amputation alone

- Pain medication (NSAIDs, gabapentin, opioids, tramadol, Amantadine)

- Bisphosphonates

- Palliative radiation therapy

What is the MST and cause of death/euth with palliative tx?

MST 2-4 months,

Local pain, pathologic fracture

What is the MST and cause of death/euth for amputation alone?

MST 4-5 months

Metastatic disease

What is the MST and cause of death/euth with amputation & chemotherapy?

MST 9-11 months

Metastatic disease

What is the MST and cause of death/euth with SRT & chemotherapy?

MST 7-8 months

Fracture, metastatic disease

What is the MST and cause of death/euth with amputation & chemotherapy & immunotherapy?

MST ~31 months

Metastatic disease