Soft Tissue Sarcomas Flashcards
What is the cell origin of a STS?
Mesenchymal
Where do STS most commonly develop in the dog?
Subcutaneous
What are biological factors of a STS:
A) Arise from?
B) Appear as?
C) Infiltrate..
D) After conervative excision
E) Mets route
F) Chemo/radio response..
A) Any anatomical site in the body;
B) The propensity to appear as pseudoencapsulated tumours with poorly defined histological margins;
C) through fascial planes;
D) Common local recurrence
E) haematogenous route;
F)A poor response in cases where gross tumour is present.
What mesenchymal tumours aren’t classified as a STS? (they can usually be reliably identified on light microscopy (especially when anatomical location is known) and because their individual biological behaviour has a more defined character) (5)
- Haemangiosarcoma
- Synovial cell sarcoma
- Gastrointestinal stromal tumours (GISTs)
- Fibrosarcoma involving the oral cavity
- Peripheral nerve sheath tumours arising from the brachial or lumbosacral plexus.
Which of the following is the most common site for metastasis of soft tissue sarcomas?
Lung
Met rate of STS?
Mild - moderate
What genes are associated with STS in canines?
P53 mutations and MDM2 gene amplification
Although little is known, what are some association of STS causes in cats and dogs?(6)
- Gene
- Chronic trauma
- FB
- Vacc
- Parasite
- Radiation
Sex and breed for STS?
no associations made
If STS if found younger, what is the nature of the STS?
More biologically active.
Median age for STS?
10-11yr
What is the normal growth rate for a STS?
Slow
Where are STS most commonly found? (3)
Head
Limbs
Trunk (incl tail)
Why are only 50% of STS diagnosed on FNA?
limited exfoliative character
What is the prognositc factor for STS?
Histo grading
What gauge percutaenous needle core biopsy for STS?
12-14fg
How can a biopsy instrument be placed into STS? (2)
- palp
- U/S guided
How many samples should you obtain as a minimum if taking a Tru-cut core biopsy?
6
What is the main risk for biopsy?
Seeding along biopsy tract
STS: OTher adjuvant diagnostic evaluations? (6)
-Routine blood work
-Radiographs of the local tumour site for possible underlying bone infiltration
-Ultrasound of the tumour
-Radiographs of the chest for possible metastatic spread
-FNA of the regional lymph node
-CT or MRI imaging techniques.
One retrospective study with 350 patients found that more than A) % of the STS resections performed in primary care practice were “B),” with the operating surgeon having no knowledge of the identity, behaviour or C) potential of the mass they were removing. The higher proportion of low‐grade (and thus less D)) forms of STS encountered in primary care practice probably compensates for this lack of E) and enables patient outcomes to remain reasonable
A) 80%
B) Unplanned
C) Invasive
D) Aggressive
E) Planning
There are currently no A) that can reliably predict the precise surgical margins required for a particular STS, but there are several validated and suspected prognostic factors that have been reported (Dennis et al. 2011). These include the B) characteristics of the tumour (i.e., grade, histologic type, mitotic count etc.), C) characteristics (i.e., size, location, palpable features), as well as other clinical factors such as patient D) and E) Following removal of the tumour, the completeness of the F) is also an important prognostic criterion to evaluate in the context of an overall treatment plan.
A) Diagnostic test
B) Histological
C) Physical
D) Age
E) Co-morbidities
F) Excision margins
What do the grading scores of STS relate to? (4)
histological differentiation,
number of mitoses per high power field,
tumour necrosis
histological grade.
Define good differentiation score 1
- Sarcomas most closely resembling normal adult mesenchymal tissue, by type (e.g., well‐differentiated perivascular wall or peripheral nerve sheath tumours, well‐differentiated fibrosarcomas, or well‐differentiated liposarcomas).
Define moderate histological differentiation score 2
Sarcomas for which histologic type can be determined, although differentiation is poor (e.g. poorly differentiated liposarcoma, fibrosarcoma, poorly differentiated perivascular wall tumour or peripheral nerve sheath tumour).
Define histological differentiation score 3
Undifferentiated sarcomas, sarcomas of unknown type.
STS Mitotic score differentiation (per 10 high power field)
1
2
3
1 0 to 9
2 10 to 19
3 >19
Define STS necrosis score
0
1
2
0 No necrosis
1 <50% necrosis
2 ≥50% necrosis
Define STS total score
1
2
3
I ≤3
II 4 to 5
III ≥6
What should be done for met check prior to removing STS?
3 thoracic xrays ( or CT)
What can be used in MRI/CT to allows the clinician to determine pre‐operatively whether the STS is anatomically confined to well‐delineated tissue barriers or has spread beyond such compartments into ill‐defined fascial planes and spaces
Contrast media can also be used to further enhance the distinction between the tumour and surrounding tissues.
Why is MRI superior to CT for STS?
Ability to distinguish difference in soft tissues.
What is the relation in recent studies between extent of resection and dx free interval/survival
No influence
Generally - what margins for STS?
Margins of 3 cm of normal tissue laterally and one clean fascial plane deep to the tumour
As well as wide margins; what else should be incorporated for high grade STS?
Radiotherapy
Tumours located on the distal limb present additional challenges because of: (3)
- the potential for compromised function if vital supportive or neurovascular structures are involved;
- poor quality (deep) fascial barriers;
- and/or the need for reconstruction of the resultant skin defect (Prpich et al. 2013).
Why should attempts for reconstructive flaps on distal limb be kept to a minimum?
poor availability of vascularised flaps
If the tumour is attached to a muscle or fascial plane this should be considered A) and the entire anatomical boundary should be B) . Fat and loose connective tissues are not barriers for infiltration of the mesenchymal tumour cells. The deep margins will almost always pose a challenge and at least C) fascial plane underneath the tumour should be removed.
A) Contaminated
B) Removed
C) One
On extremities, surgical margins are difficult to achieve and A) resection in the absence of orthopaedic and neurologic abnormalities can be an option for high grade STS, however a more B) approach with ‘limb spare’ techniques may be a better alternative for low to intermediate grade tumours.
A) Radical
B) Conservative
Marginal excision of a STS either as a sole therapy or combined with radiation therapy may result in an excellent long-term outcome with lower morbidity compared to…
Amputation
Define thick barrier
A physically strong membranous tissue such as joint capsule
Describe thin barrier
A weaker membranous tissue; includes muscle, fascia, periosteum in adults, epineurium, etc
How to STS tend to grow - in respect to barriers
will preferentially expand within the structure of origin along the path of least resistanc
Clean histo margin is associated with .. (2)
significantly improved survival and prolonged tumour‐free intervals.
An incomplete surgical margin does not mean tumour recurrence is inevitable.
True or false?
True
Recurrence rate incomplete STS margin?
17-28%
How many dogs with a clean STS margin recur?
8%
What creates a circumscription to STS?
psuedocapsule
What creates STS pseudocapsule?
By the compression and atrophy of the surrounding tissue as the tumour expands centrifugally.
What is the eactive zone and may sometimes be visible grossly as a discoloured area that surrounds the tumour?
continued expansion of the tumour, a reaction can develop between the capsule and normal tissue, which includes mesenchymal cell proliferation, influx of inflammatory cells, haemorrhage, tissue oedema, vascular neogenesis and other granulomatous changes
Why is the lab not always reliable for margins?
They often has parts of samples, and do not look at each margin
Small buds of sarcoma cells regularly extrude through the reactive zone and form small isolated nodules - what are these called?
satellite nodules or skip metastases
A recent paper described compartmental tumour excision as a paradigm shift from circumferential to longitudinal resection, and that it offered the following advantages: (3)
- Allows complete removal of an involved muscle compartment, even if only partially affected by the tumour, and more adequately addresses the potential spread of the micro‐metastatic satellite nodules contained within an ill‐defined anatomical boundary around the tumour.
- Enables the surgeon to perform a radical oncological resection while at the same time eliminating non‐selective demolition.
-With preoperative coaxial imaging, the anatomical relationship of the tumour with surrounding structures will improve surgical planning and reconstruction efforts, and may allow true anatomical boundaries of a tumour to be identified and exploited.
When should radiotherapy be given in relation to surgery?
Radiotherapy may be employed either before (neoadjuvant) or after (adjuvant) surgery. While there is no proven difference in disease outcome according to treatment sequence,
Chemo with STS?
The value of chemotherapy in veterinary patients remains unclear, as robust evidence is limited.
What chemo drug of choice for STS?
Doxorubicin
Low‐dose continuous chemotherapy – or A) chemotherapy – has received increasing interest because of its apparent ability to prevent tumour recurrence in dogs with B) resected STS
A) Metronomic
B) Incompletely
Rather than being directly A) , metronomic chemotherapy is thought to inhibit tumour growth via a combination of anti‐angiogenic and some B)effects
A) Cytotoxic
B) Immunomodulatory
One study compared the outcome of 30 treated dogs with 55 controls and identified significantly A) disease‐free intervals for patients on metronomic chemotherapy (Elmslie et al. 2008). However, selection bias in the control population may have B) the conclusions of this study because 100% of the control dogs developed tumour recurrence or were censored from the analysis.
A) Improved
B) Skewed
Why may neoadjuvant chemo be better?
achieve better tissue penetration because the microvasculature of the tumour has not been disrupted by surgery.
How might neoadjuvant chemo improve the odds for complete surgical excision?
confine the tumour extension to a more definable boundary,
Prognosis for STS?
Good - if complete resection
STS met rate
1.7% - 41%
local recurrence rate?
up to 75%
When will most recurrences happen?
Within 2 years
