Sa Med - Oncology - Helfand P2

Front 1

What is the most common malignant skin tumor in the dog?

Back 1

Mast cell tumors (7-21% - most are low or intermediate grade)

Front 2

Multiple cutaneous mast cell tumors is a sign of ____.

Back 2

Nothing! Not a sign of metastasis or systemic dz

Front 3

What are the 3 "B" breeds predisposed to canine MCT?

Back 3

Bostons, Boxers, Bulldogs (the brachycephalics - but any dog can get them)
-> almost more likely to be Benign

Front 4

How do MCT appear upon PE?

Back 4

Alopecic, erythematous cutaneous "button" lesion
soft & fluctuant or firm, superficial, deep, moveable or fixed, smoother or ulcerated

Front 5

What percentage of MCT FNAs won't stain with Diff Quik?

Back 5

10%

Front 6

How is anatomical staging of MCT done?

Back 6

Lnn: FNA *even if norm on palpation*
Liver/spleen: abdominal ultrasound
Bone marrow: aspirate but rare to do anymore
Lungs: rare - rads but waste of time

Front 7

MCT histological grade...
...aggressive local invasion of tissue requiring aggressive local therapy

Back 7

Grade I & II

Front 8

MCT histological grade...
...low risk of metastasis

Back 8

Grade I & II

Front 9

MCT histological grade...
...higher risk of metastasis

Back 9

Grade III

Front 10

MCT histological grade...
...chemotherapy indicated

Back 10

Grade III - local therapy alone = suboptimal

Front 11

Median survival time for a grade III MCT?

Back 11

6 months post surgery

Front 12

What are the 2 important pieces of information you're looking for from a biopsy report?

Back 12

Tumor grade
Margins of excision

Front 13

What is the most significant prognostic factor for MCT?

Back 13

Histological grade -> invasiveness into tissue!
determined only by histo exam of TISSUE BIOPSY

Front 14

Which anatomical locations are MCT most difficult to treat?

Back 14

On the head and feet

Front 15

Prognostic factors for a MCT?

Back 15

Location, location, location,
Histological grade
Clinical stage
(also clinical signs, recent rapid growth/ulceration, recurrence)

Front 16

What is the most important proto-oncogene in a mast cell tumor? Where is it located?

Back 16

C-kit
membrane, cytoplasm, nuclear

Front 17

Because kinase domain mutations (ITD) cause constitutive activation, mutations in the _____ domain is correlated with a higher grade tumor.

Back 17

Juxtamembrane domain

Front 18

Which therapy for canine MCT...
...treatment of choice

Back 18

Surgical excision

Front 19

Which therapy for canine MCT...
...for local control of a 1º if excision is incomplete

Back 19

Radiotherapy

Front 20

Which therapy for canine MCT...
...for grade III tumors

Back 20

Chemotherapy (or if sx/RT isn't an option)

Front 21

Which therapy for canine MCT...
...ancillary therapy

Back 21

H1 & H2 blockers
Sucralfate if ulcerative

Front 22

Which therapy for canine MCT...
...not chemotherapy or radiotherapy and definitely not surgery but...

Back 22

Tyrosine Kinase Inhibitors

Front 23

What is considered aggressive surgery for a MCT? What is the goal?

Back 23

3 cm margins in all lateral directions and 1 (to 2) fascial planes deep
(radical: amputation, body wall resection, partial maxillectomy/mandibulectomy)

Goal: local control of tumor

Front 24

You've just done surgery on a dog with a mast cell tumor. How do you know if any additional treatment is necessary?

Back 24

Biopsy report says GI or II, & is completely excised & staging tests are negative

Front 25

What are the local recurrence rates & metastasis rates for a completely excised Grade II MCT?

Back 25

5% recurrence
5% metastasis

Front 26

What is the prognosis for radiotherapy on a grade II MCT that as been incompletely resected?

Back 26

85 - 95% 2 year local control

Front 27

What is the prognosis for incompletely excised grade II tumors and are not followed up with re-excision or radiotherapy?

Back 27

17% recurrence at 1 yr
22% recurrence at 2 yrs
33% recurrence at 5 yrs

Front 28

When is chemotherapy indicated as a therapy for MCT?

Back 28

Risk of metastasis
Other therapy declined or not feasible

Front 29

What factors increase the risk of MCT metastasis?

Back 29

High grade tumors
"Unfavorable" locations
Lnn metastasis
Mitotic index >5
+/- many multiple tumors

Front 30

What chemotherapy drugs are used to treat MCT when indicated?

Back 30

Prednisone & Vinblastine (well tolerated & relatively inexpensive)

Front 31

How does Grade III MCT prognosis compare when chemotherapy is used vs not at all?

Back 31

Improvement in survival: 331 days vs 6 months

Front 32

What tissue is at greatest risk for spread of MCTs?

Back 32

Lymphoid tissue/lnn

Front 33

What vasoactive amines are found in the mast cell granules that cause mast cell tumors to really look like whatever the hell it wants?

Back 33

Histamine, Heparin

Front 34

Recommended therapy for...
...Grade I MCT

Back 34

local therapy: surgery, RT if incision is incomplete

Front 35

Recommended therapy for...
...Grade II MCT

Back 35

local therapy: surgery, RT if excision is incomplete (+/- chemo, TKI)

Front 36

Recommended therapy for...
...Grade III MCT

Back 36

local therapy: surgery, RT + chemo; TKI

Front 37

What are the different anatomical forms for feline mast cell tumors & their prognoses?

Back 37

Cutaneous MCT: mostly benign clinical cases

Visceral MCT (splenic form): good prognosis w/ splenectomy!

Intestinal MCT: Grave prognosis

Front 38

When would a feline visceral MCT have a poor prognosis?

Back 38

Any combination of splenic, cutaneous & intestinal involvement = metastatic (splenectomy would be of little benefit)

Front 39

What is the chemotherapeutic agent of choice for treating feline MCT?

Back 39

CCNU (lomustine) - 50% response rate
MST 130 days (only anectodal data about vinblastine in cats)
Gleevec tolerated well

Front 40

What is the greatest risk factor for development of cutaneous squamous cell carcinoma in dogs & cats?

Back 40

Solar exposure
5% in dogs
15% in cats

Front 41

Compare feline and canine sites of occurrence of SCC

Back 41

Feline: nasale planum, eyelids, pinna

Canine: subungual (nail bed), scrotum, nose, legs, perianal region, flank/ventral abdomen

Front 42

What percentage of nail bed tumors are SCC?

Back 42

33% (1/3)

Front 43

What are two differentials for lytic bone lesions seen on radiographs in the nail bed region?

Back 43

Osteomyelitis, SCC

Front 44

What is Bowen's disease?

Back 44

multicentric SCC in situ - papilloma virus (so unrelated to sun exposure) causing lesions in the haired/pigmented areas of skin

Front 45

What is the treatment of choice for SCC?

Back 45

Surgery

Front 46

When would chemotherapy be indicated as treatment for SCC? Radiotherapy?

Back 46

Chemotherapy: high grade lesions; intralesional therapy

Radiotherapy: superficial for early lesions, external for deeper lesions - smaller tumor = better outcome

Front 47

What do TKIs target?

Back 47

Stem cell factor
(tyrosine kinases encoded by the proto-oncogene c-kit)

Front 48

C-kit is also known as ____?

Back 48

CD117

Front 49

What was the first TKI marketed? Why should we know this one?

Back 49

Imatinib - (Gleevec)
trials for this drug were done up at OHSU - a "claim to fame"

Front 50

At which axon do most mutations occur on c-kit?

Back 50

Axon 11 - the juxtamembrane domain
mutations here are correlated with higher grade tumors

Front 51

What is the brand name for SU11654 and toceranib?

Back 51

Palladia (a TKI)

Front 52

How does TKI targeting help to inhibit proliferation of malignant mast cells?

Back 52

The mast cells express stem cell factor receptor that can be blocked by a TKI thus preventing activation