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Onco 7 STS

sihirlifil's version from 2018-05-03 14:46

Soft tissue sarcoma

Question Answer
What are STS?Mesenchymal tumors, heterogenous, arising from connective tissue elements, arise from many nonbony connective tissues
May originate in visceral & nonvisceral sites
Differing morphological features, share similar biological behaviors
(nomenclature) Fibrosarcoma =fibrocyte
(nomenclature) Osteosarcoma =bone
(nomenclature) Hemangiopericytoma =pericyte
(nomenclature) Liposarcoma =Adipocyte
(nomenclature) Rhabdomyosarcoma =striated muscle
(nomenclature) Schwannoma, neurofibrosarcoma =Malignant nerve sheath tumors
(nomenclature) Myxo(fibro)sarcoma =myxomatous tissue
(nomenclature) Chondrosarcoma =chondrocyte
(nomenclature) Leiomyosarcoma =smooth muscle
(nomenclature) Malignant fibrous histiocytoma =histiocyte
(nomenclature) Synovial cell tumor =synovium
Tumors with ‘-sarcoma’ suffix that ARE NOT STSHemangiosarcoma, Lymphangiosarcoma
Higher grade, higher metastatic potential, hematopoietic origin not supportive tissue
How do STS exfoliate?POORLY!
Signalment of STSMid-older dogs, med-large breeds
STS looks like?Firm, fixed mass on trunk, extremities, oral cavity
Confused with lipomas: soft & lobulated
CS of STSDepends on organ involved/location
GI: V+, D+, anorexia, weight loss
Oral cavity: halitosis, dysphagia, anorexia
Peripheral nerves: pain, lameness, swelling, CNS signs
Bladder: hematuria, stranguria, dysuria
What’s tricky about STS?Well encapsulated, amenable to easy resection, conservatively ‘shelling out’ of capsule… BUT! Pseudocapsule = layer of compressed tumor cells & reactive fibrovascular tissue microscopic dz --> local recurrence w/ a vengeance :(
How to dx STS?Same for other tumors, but advanced imaging comes more into play
Complete PE, minimum database, regional LN, palpate mass, thoracic & affected limb rads, CT scan, MRI
How is cytology of STSGenerally poor cytologic yield
Tumor necrosis, inflammation
Clinical stage based onTumor size
Fixed to surrounding tissue
Status of regional LN
Presence of distant metastasis
How do you get a definitive dx of STS?Biopsy with histopathology
2 approaches to biopsyIncisional: make sure biopsy tract can be removed en bloc
***STS Grading Scoring System: 1 =Differentiation: Resembles normal tissue
Necrosis: None
Mitotic figures: 0-9/HPF
***STS Grading Scoring System: 2 =Differentiation: Specific histologic type
Necrosis: <50%
Mitotic figures: 10-19/HPF
***STS Grading Scoring System: 3 =Differentiation: Undifferentiated (e.g. mass in FL with bladder cells)
Necrosis: >50%
Mitotic figures: >20/HPF (increased risk of mets!)
TOC for STSChance to cut = chance to cure! WIDE, AGGRESSIVE SURGICAL EXCISION! often requires reconstructive sx. 2-3cm margins including muscle or fascial plane below
How is long-term disease control with complete excision?80% long term, 20% recurrence
Difficulties w/ 2nd surgeryMore aggressive tumor type, increased patient morbidity, increased cost to client
**Which tumors do we typically gradeSTS & MCT
How is radiation therapy for STS?Good additional modality. historically considered radiation-resistant but combine with cytoreductive sx, pre and post-op. surgery is mainstay but sometimes can’t get all of the tumor b/c of where its located, makes it difficult to get the margins we want, radiation to clean it up
Radiation + cytoreductive sx: cure rate for grade I?90-95% :)
Radiation + cytoreductive sx: cure rate for grade II?80-85%
Radiation + cytoreductive sx: cure rate for grade III?70-75%
How is radiation used pre-op?Smaller surgical field, consolidation/shrinkage of tumor. DISADV: poor/delayed wound healing
How is radiation used post-op?Clean up dirty margins
How is chemotherapy for STS?NOT EFFECTIVE ALONE! Best combined w/ radiation & sx. Reserved for high grade (targets rapidly dividing cells, III has high mitotic figures))
Prevent or delay metastasis
Doxorubicin = mainstay

Injxn site sarcomas (aka VAFS)

Question Answer
Which vaccines triggered suspicion?IMRAB 3 (1985): subQ killed rabies virus vaccine (aluminum adjuvant)
First killed aluminum-adjuvanted FeLV vax intro in 1985
First epidemiological study in 1992, when 61% increase in FSA ID’d in biopsy population from 1987-1991
Retrospective epidemiological study found…Repeat vax in 1 site increased risk over non-vax. No specific brands
Cats w/ VS tumors that had been admin a single vax received rabies (37%), FVRCP (33%), FeLV (30%)
RECORD! multiple sites & inform owners
What is the objective of the Vaccine-Associated Feline Sarcoma Task Force?Define scope & incidence; determine causal & prognostic factors; develop plan to educate & inform
Who gets VAFS? (…actually, more like who doesn’t)Not a syndrome in dogs! Not prevalent in countries where rabies & FeLV not admin (Japan, Australia, Holland)
Proposed factors for VAFSNeedle gauge
Syringe reuse
Vax temperature
Shaking of the syringe
Massaging vaccination site
**VAFS seen a lot with what concurrent dz?Renal patients! getting subQ fluids all the time!
Etiology of VAFSInflammatory reaction! Post-vax inflam occurs in 80-100% of cats (2x more in rabies than FeLV). Aluminum = most consistent reactions (non-adj & 3-yr rabies = no inflam)
Vax --> inflam cytokines --> reactive fibroblasts --> loss of cellular replication control mechanisms --> neoplasia
(other factors etiology)(individual susceptibility, loss of normal p53 fxn, growth factors e.g. PDFG, EFG, TGF-beta which may be released from lymphocytes, transform normal fibroblasts)
Estimate prevalence today?2,200 to 22,000 cats a year!
When do they occur?Median 340d after vax (26m post-rabies vax, 11m post-FeLV). can be up to 10 years after! 93% developed w/in <4y
How do VAFS behave?Radiosensitive (reduce tumor size before sx)
Rapid growth/invasive
Seldom metastasize? (10-25%) --> lungs, eyes, other
What affects prognosis of VAFS?# of surgeries, completeness of excision, histo grade(?), cytoplasmic expression of p53 (IHC)
What do you think of this CT?
THIS IS WHY WE NEED CT for sx planning! Have to see how invasive it is (can feel palm of hand but not all the fingers) Can see contrast medium delineating the pseudocapsule, extending way far down… prob needs scapulectomy & possibly part of vertebra :(
What is the 1, 2, 3 rule?(dx, treat, prevent) If you get a vax reaction that is: Still growing 1m after vax, >2cm in size, persists >3m after vax = need to get biopsy, try to remove… chances are, will encounter vax-associated sarcoma
T/F Cytology considered reliable for VAFSNOO! once again EXFOLIATES POORLY
How do you do the biopsy for VAFS?Incisional recommended. also have to remove biopsy tract location (contam)
VAFS pre-tx evaluation (3)FeLV testing, Radiographs, CT scan/MRI (follow contrast enhancer… goes all the way around)
Treatment of VAFS?Aggressive sx excision (REFERRAL better!)
>2-3cm margins, including bone (most surgeons say 5). mark margins, be aware of pseudocapsule, plan for radiation
Do we wanna place a drain? why/not?DO NOT PLACE DRAINS! Contaminates everything!!!
what happened here???
What is the recurrence rate for VAFS?~50% local recurrence rate, even if margins look clean on histo (100% if you don’t get all the cells)
On avg occurs w/in 6m, may be as early as 2 weeks
Why do we do pre-op radiation?Cytoreduction, overall survival 600d (better than post-op_
Local failure in 46% --> more aggressive
Why do we do post-op radiation?For incomplete excision
MST 343 days
Do we use chemo for VAFS?Only for higher grades. SEffx minimul w/ most drugs but include: decreased appetite, loose stool, whisker loss (lolwut). Cats generally resistant to myelosuppression
(which chemo agents do we use)(Doxorubicin, cyclophosphamide, carboplatin, mitoxantrone) (no survival advantage, minimal responses)
Recommended vax sitesRabies Right, FeLV Left. others R shoulder, subq & not intrascapular

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