Tumors Of The Appendicular Skeleton- Osteosarcoma

Question 1

What’s the signalment for OSA?

Answer 1

Large to Giant breeds (>40 kg)
— Irish wolfhounds, GSD, Great Danes, greyhounds

Male predisposition but gonadectomized are 2x increased risk (esp. rotties)

Bimodal distribution: 1-2y; 7-9y

Question 2

What is the most common site for OSA?

Answer 2

Distal radius,
Then proximal humerus…
(Away from the elbow, twd the knee)
Distal femur,
proximal tibia

Question 3

What part of the bone is favored in development of OSA?

Answer 3

Metaphyseal region

Question 4

What might be elevated on chemistry profile in a dog with OSA?

Answer 4

ALP!

Question 5

What is Codman’s triangle?

Answer 5

Periosteal lifting caused by subperiosteal hemorrhage

As the tumor is moving from the endosteal surface out, it can disrupt the periosteum, and it can pop up the periosteum from hemorrhage..

Question 6

T or F: OSA sometimes spans across joints from one bone to another.

Answer 6

FALSE. Does NOT cross joints!

Question 7

What is the prognosis for OSA if the patient is provided with palliative care (analgesia) only?

Answer 7

MST: 1-3 months

*RT MST: 4-10 months*

Question 8

What’s the prognosis for OSA if the patient undergoes curative intent Stereotactic Radiosurgery (SRS) alone?

Answer 8

MST: 4-6 months

Question 9

What’s the prognosis for OSA if the patient undergoes surgery (or SRS) and chemotherapy?

Answer 9

MST: 8-12 months

Question 10

For every _____U/L increase in total ALP increases the risk of tumor-related death by _____%.

Answer 10

100; 25

Question 11

T or F: FNA/cytology is preferred over biopsy in the diagnostic algorithm for OSA.

Answer 11

True

Question 12

In the case of a proximal femoral OSA lesion, what are the more “aggressive” surgeries we would need to implement for local control?

Answer 12

En-bloc acetabulectomy OR Subtotal hemipelvectomy

Question 13

With regard to OSA amputation results, thoracic limb amputees tend to have more difficulty in _______________ , whereas pelvic limb amputees have more difficulty __________.

Answer 13

Keeping balance; Gaining speed

Question 14

Severe osteoarthritis,
Neurological disease,
Morbid obesity

(in an existing OSA case) Are all indications for ….?

Answer 14

Limb salvage!

Question 15

Pathological fracture,
Extensive soft-tissue involvement,
Poorly compliant owner or patient,
Large lesion >50% diaphysis,
Advanced disease,
And inappropriate location of tumor

(in an existing OSA case) Are all indications for what?

Answer 15

They’re CONTRAindications for limb salvage!

Question 16

What’s the preferred site for surgical limb salvage?

Answer 16

Distal radius (most common site of tumor occurrence)

Question 17

How can isolated ulnar lesions be treated?

Answer 17

Ulnectomy! Including the excision of styloid process (Distal location preferred)

Question 18

In the cases of limb salvage surgery, what adjunctive therapy needs to follow?

Answer 18

Cytotoxic chemotherapy!

Question 19

What is stereotactic radiosurgery (SRS)?

Answer 19

Entire radiation dose is delivered in a single treatment through the use of multiple, noncoplanar beams of radiation that are stereotactically focused on the target…

Question 20

What are the major benefits of SRS?

Answer 20

Minimizes damage to healthy surrounding tissues by relying on extreme accuracy of radiation delivery to a tumor,
Steep dose gradient between the tumor and surrounding healthy tissues…

Question 21

What is the best site for SRS based on low P.O. fracture rate in limb salvage?

Answer 21

Proximal humerus

Question 22

What are the adjunctive chemotherapy options for OSA?

Answer 22

Cisplatin, Carboplatin, Doxorubicin

Question 23

How do amino-bisphosphonates exert their effect?

Answer 23

They act on osteoclasts via inhibition of the mevalonate pathways, which results in disruption of intracellular signaling and induction of apoptosis.

Question 24

Zoledronate and Pamidronate are examples of ?

Answer 24

Aminobisphoshonates… Demonstrated pain palliation in 30-50% of treated dogs

Question 25

How does RT provide palliative therapy in OSA patients?

Answer 25

Reduces local inflammation, minimizes pain, slows progression of metastatic lesions, improves QOL

Question 26

Development >300 days after initial diagnosis,
<3 radiographically evident metastatic lesions,
And no doubling in size of lesions or development of new lesions in a 4-week period

(in an existing OSA case) Are indications for what?

Answer 26

Pulmonary metastatectomy

Question 27

What part of the bone is OSA more common in the feline?

Answer 27

Diaphysis

Question 28

MST for OSA when providing only palliative care…?

Answer 28

1-3 months

Question 29

MST for OSA when treated surgically alone…?

Answer 29

4-6 months

Question 30

MST for OSA when surgery and chemotherapy are combined in treatment…?

Answer 30

8-12 months

Question 31

T or F:
Cats with appendicular OSA may be cured with amputation alone (no chemo).

Answer 31

True.
MST: 24-49 months