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Y4 SA - Oncology > Sarcomas > Flashcards

Sarcomas Flashcards

1
Q

What is a sarcoma?

A

A malignant cancer that arises from transformed cells of mesenchymal origin
Cells that lack polarity and are surrounded by significant stroma

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2
Q

Name the subtypes of sarcomas based on their origin:
- Bone
- Connective tissue
- Blood vessels
- Muscle
- Fat
- Cartilage

A
  • Bone = osteosarcoma
  • Connective tissue = soft tissue sarcoma, fibrosarcoma
  • Blood vessels = haemangiosarcoma
  • Muscle = rhabdomyosarcoma (striated muscle), leiomyosarcoma (smooth muscle)
  • Fat = liposarcoma
  • Cartilage = chondrosarcoma
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3
Q

Describe the general behaviour of sarcomas

A

Locally invasive
Metastatic risk varies with tumour type

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4
Q

The metastatic risk of sarcomas is highest in which tumour types?

A

Osteosarcoma
Haemangiosarcoma
Histiocytic sarcoma

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5
Q

For soft tissue sarcomas, fibrosarcomas and peripheral nerve sheath tumours metastatic potential is affected by?

A

Grade

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6
Q

Define the stage of a tumour

A

Extent: how far has it got?
Clinical assessment of current disease burden
Does the disease burden limit outcome ?

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7
Q

Define the grade of a tumour

A

Histological features
Activity, Vascularity, Invasion,
Necrosis, Differentiation
What is the likely behaviour ?

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8
Q

How can sarcomas be diagnosed?

A

Fine needle aspiration and cytology
Biopsy and histology +/- IHC

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9
Q

How can you stage sarcomas?

A

Is there evidence of metastasis ?
- Aspiration of local lymph nodes, even if palpably normal
- Imaging dependent upon tumour type
- Sample other abnormalities identified on examination

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10
Q

Describe the uses of FNA for sarcomas

A

Cheap, quick can be done without sedation or GA
Higher chance of non-representative sample
No grade

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11
Q

Describe the uses of a Tru-cut biopsy for sarcomas

A

Small samples
Chance of non-representative sample – diagnosis or grade
May be possible to do under sedation

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12
Q

Describe the uses of a biopsy and histology for sarcomas

A

Larger samples therefore better chance of diagnosis and accurate grade
Requires GA, more morbidity and cost

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13
Q

Describe radiography of primary sarcomas

A
  • Radiographs relatively insensitive
  • more than 60% of mineral content of bone must be lost for lysis to become apparent
  • All soft tissues except fat look the same
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14
Q

Describe the use of CT for imaging primary sarcomas

A

Better appreciation of osteolysis or new bone production
Many more shades of grey (different tissues)
Surgical planning
Radiation planning

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15
Q

Describe the use of MRI for imaging primary sarcomas

A

Excellent for surgical planning esp trunk/body wall

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16
Q

Most sarcomas metastasise via which route?

A

Haematogenous

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17
Q

In which cases of sarcomas would you want to FNA local and regional LNs?

A

FNA if node palpably abnormal and in all cases where LN metastases more likely:
- Higher grade tumours
- Suspected histiocytic tumours
- Tumours around joints

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18
Q

Describe distant metastasis of sarcomas, and how to diagnose this

A

Depends on tumour type
All sarcoma’s have a predilection for lung metastasis:
- Inflated (i.e. under GA) 3 view thoracic radiographs
- CT is more sensitive if available

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19
Q

Describe the limitations of imaging for sarcomas

A
  • Limitations of x-ray
  • Increased sensitivity of CT for bone involvement and pulmonary nodules
    What are the lesions?
  • Lung lesions often cannot be sampled
  • Not all nodules are metastatic
  • Larger and/or more numerous tend to be metastases
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20
Q

Soft tissue sarcomas are most commonly seen in which patients?

A
  • Middle to large breeds may be predisposed
  • Median age 8 -11 years
  • Some breed predilections e.g. fibrosarcomas in Retrievers
  • Younger animals in predisposed breeds
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21
Q

Describe the treatment algorithm for soft tissue sarcomas

A
  • Biopsy confirmed soft tissue sarcoma
  • Wide surgical margin excision
  • If margins are histologically complete, grade tumour
  • If margins are histologically incomplete, wide surgical resection of scar or adjunctive radiation therapy
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22
Q

How should patients with grade 1 and 2 soft tissue sarcomas be managed following removal?

A

Routine follow up at 1, 3, 6, 9, 12 and 18 months

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23
Q

How should patients with a grade 3 soft tissue sarcomas be managed following removal?

A

Routine follow up at 1, 3, 6, 9, 12 and 18 months
Consider adjunctive chemotherapy with doxorubicin based protocol

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24
Q

What should be done if a soft tissue sarcoma has a pseudocapsule?

A

Do not try to shell the tumour out of this - remove it all

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25
Q

Describe the ideal surgical margins for a soft tissue sarcoma

A
  • 3 cm lateral and 1 fascial plane beyond the extent of tumour
  • ‘Tumour’ includes FNA tracts and biopsy scars
  • Not always possible, limited by anatomy
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26
Q

How are margins of excision assessed?

A

Most common method: cardinal
- 3 sections
- Relies on mass being spheroid
- Not always true
- Sarcomas (and other) tumours invade along tissue planes

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27
Q

Name two other methods of sample preparation for margin assessment

A

Bread loafing
Shaved margins

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28
Q

Margins of excision are assessed and the results can be one of 3 categories, what are they?

A

Complete excision
Incomplete excision
Excision with narrow margins (1 - 3 mm between tumour and sample edge)

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29
Q

Describe the features of incomplete tumour excision

A
  • Residual tumour tissue
  • Tumour cells within < 3 mm of tissue edge
  • Probability of recurrence dependent upon tumour type and grade
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30
Q

If there is microscopic residue of a tumour following removal, what are the further treatment options?

A
  1. Further wide surgical excision
    - Ideally treat the scar as a tumour and aim for wide surgical excision
  2. Adjuvant radiation therapy
    - Ideally delivered as a fractionated protocol i.e 12 or more rather than 4 fractions
    - Highly effective tumour control
31
Q

Describe metronomic chemotherapy as a treatment option for microscopic residual disease

A
  • Continuous, low dose therapy
  • Usually low dose cyclophosphamide with piroxicam or meloxicam
  • Main target is angiogenesis: immunomodulatory effects
32
Q

Describe active monitoring as a treatment option for microscopic residual disease

A
  • Generally a terrible idea as most recur and acting before this happens will give better outcome
  • Only when chance of recurrence is considered low e.g. low grade STS
  • When a complete excision was expected
  • When there are questionable margins in one small area
  • Check by vet monthly for at least a year
33
Q

Describe the prognosis in patients with resectable tumours without metastatic disease

A

Successful surgery +/- RT associated with very good survival MST > 4 years

34
Q

List 4 prognostic factors for sarcomas

A

Tumour grade and mitotic rate
Tumour size
Tumour location
Achieving local control of the tumour

35
Q

Anti-metastatic treatment is used for which tumours?

A

For high (and possibly intermediate grade) STS.
Also occasionally used palliatively for non-resectable disease and no other options

36
Q

Name the tumour that develops at at sites where cats typically get injections

A

Feline injection site sarcoma

37
Q

Describe the histological appearance of feline injection site sarcomas

A

Malignant fibroblasts
Inflammation – often high lymphocyte component
Macrophages taking up foreign material thought to be adjuvant / carrier

38
Q

Describe the 3-2-1 rule for feline injection site sarcomas

A

Any mass present for 3 months or longer
Any mass greater than 2cm diameter
Any mass that continues to increase in size 1 month after injection

39
Q

Which biopsy type can be used for feline injection site sarcomas?

A

Incisional biopsy
- Excisional biopsy almost guarantees treatment failure

40
Q

Describe diagnosis and staging of feline injection site sarcomas

A
  • Advanced imaging
  • Local staging: assessing size, margins as highly invasive
  • Distant staging: variable metastatic rate, haematogenous route
41
Q

Describe the margins needed for feline injection site sarcoma excision

A

(3 –) 5+ cm lateral surgical margins and 2 fascial planes deep
This can involve removal of spinous processes of vertebrae

42
Q

Describe treatment for non-resectable feline injection site sarcomas

A

Pre-operative radiation therapy and / or chemotherapy can be useful

43
Q

Describe treatment for incomplete resections or marginally resected feline injection site sarcomas

A

Use of adjuvant radiation therapy associated with the best outcomes.
After Sx and definitive RT:
- 1 year survival – 86%
- 2 year survival 44 – 71 %
- 3 year survival 28 – 68 %

44
Q

Describe Doxorubicin based chemotherapy for treating feline injection site sarcomas

A

Possibly longer disease free interval in cats treated with surgery, radiation therapy and then chemotherapy
Risk of nephrotoxicity

45
Q

Describe the recommendations for preventing feline injection site sarcomas

A
  1. Injections to be given in sites amenable to wide surgical excision e.g. limb or tail
  2. Reduce inflammatory reactions at injection sites – avoiding irritating substances where possible
  3. Do not over-vaccinate
46
Q

85% of bone tumours are …?

A

Osteosarcomas

47
Q

Describe the predispositions for osteosarcomas

A

Middle age and older dogs
Typically large breeds
- Appendicular skeleton: metaphysis of long bones
- Front limbs 2:1 hind limbs
- ‘Near the knee away from elbow’

48
Q

Describe the clinical signs of bone tumours

A

Pain and lameness
- Sudden or progressive onset
- Localisable to a single bone
Swelling

49
Q

Describe the radiographic changes of bone tumours

A

Do not differentiate tumour type
- Bone lysis
- Soft tissue swelling
- New bone: palisades perpendicular to bone – sunburst
- Periosteal elevation: Codman’s triangle
- Long zone of transition
- Does not cross joint

50
Q

How can bone tumour diagnosis be confirmed?

A

Cytology or histology required to confirm diagnosis

51
Q

What are the main DDx of bone tumours?

A

Osteosarcoma
Chondrosarcoma
Histiocytic sarcoma
Fibrosarcoma
Haemangiosarcoma
Myeloma / lymphoma (round cell tumour)
Fungal osteomyelitis
Metastatic tumours (carcinoma)
Benign tumours/cysts

52
Q

What are the aims of treating bone tumours?

A

Prevention of pain
Delaying development of metastases and extending life

53
Q

Describe amputation as a treatment method for bone tumours

A

Most dogs tolerate amputation very well
- Even large dogs and those with mild to moderate orthopaedic problems
- If it walked in on 3 legs it can walk out on 3 legs
Patients pain free around 1 week after amputation
Complete ambulatory adaptation takes around 1 month

54
Q

How can you reduce pain in patients with bone tumours?

A
  • Amputation will eliminate pain
  • Analgesics: multimodal approach - opioids, NSAIDs, paracetamol
55
Q

Which drug can be used to slow bone destruction

A

Bisphosphonates e.g. pamidronate q 4 weeks

56
Q

How can sensation of bones be reduced?

A

Radiation therapy
1 fraction yields pain relief in 60 – 90 % for 1 – 3 months

57
Q

What % of osteosarcomas have metastasis at diagnosis?

A

95%

58
Q

How does the location of osteosarcomas influence prognosis?

A

Appendicular:
- Humerus poorer prognosis than other
- Rib, vertebral and pelvis OSA all have poorer px
Axial:
- Skull OSA has lower metastatic rate
- Local invasion bigger problem
- Maxilla or calvarium worse px

59
Q

Describe the main features of feline osteosarcomas

A

Much lower metastatic potential
Amputation may cure

60
Q

What are haemangiosarcomas?

A

Tumours of blood vessel walls
- Can affect any tissue

61
Q

Which tissues are most commonly affected by haemangiosarcomas?

A

Most commonly spleen (around a third of splenic tumours, half of malignant)
Also liver, right auricular appendage, muscle, skin

62
Q

Describe the behaviour of haemangiosarcomas

A

Highly invasive and metastatic

63
Q

Describe the clinical signs of haemangiosarcomas

A

Clinical signs usually associated with bleeding
- Shock, collapse, haemoabdomen or pericardial effusion
- Intramuscular: bruising in the dependent part of the limb
- Pericardial effusion if right auricular appendage

64
Q

Describe the clinical pathology changes seen with haemangiosarcomas

A

Clinical pathology changes reflect bleeding and altered coagulation:
- Anaemia and sometimes schistocytosis
- In early stages of bleeding - effusion and reduced TP precede measurable anaemia
- Low platelet count
- Prolonged coagulation tests and DIC

65
Q

Prior to a splenectomy due to a haemangiosarcoma, what needs to be done?

A

Staging of the tumour

66
Q

How can haemangiosarcomas be staged?

A

Thoracic and abdominal +/- cardiac imaging
In older dogs hyperplastic liver nodules cannot be differentiated from metastasis on appearance alone - requires cytology /histology

67
Q

Describe the poor prognostic factors for haemangiosarcomas

A

Tumour rupture and bleeding into the abdomen
- but diagnosis often not known at this point
- Other types of splenic tumour will also rupture
Invasive tumours in other sites

68
Q

How can primary haemangiosarcomas be treated?

A

Surgery
- Splenectomy
- Compartmental or wide excision in other sites

Survival after splenectomy depends on stage - short if gross metastases already
In non-visceral sites, moderately responsive to radiation

69
Q

What must you be aware of, that may develop, following a splenectomy

A

Ventricular arrythmias

70
Q

Describe treatment for metastatic haemangiosarcomas

A
  • Survival with metastasis typically 4 – 6 weeks for splenic
  • Chemotherapy more useful if no gross metastasis
  • For splenic HSA if no metastasis on staging sx alone MST ~ 2-4 mths; sx + Doxorubicin MST ~ 4 - 6 mths
71
Q

What is a histiocytic sarcoma

A

Highly metastatic sarcoma
Arising from histiocytes – professional antigen presenting cells of the immune system

72
Q

Which breeds are predisposed to histiocytic sarcomas?

A

Flat coated retriever, Bernese mountain dogs

73
Q

Which organs/tissues can be affected by histiocytic sarcomas?

A

lung, spleen, liver, bone, brain and joint

74
Q

How are the best outcomes of histiocytic sarcoma treatments achieved?

A

Multimodal therapy
- Surgery, radiation and lomustine/anthracycline chemotherapy
- Dogs with gross metastasis have quite short survival: MST circa 4 – 5 months
- Dogs with complete response to therapy or no metastasis at diagnosis who have chemotherapy live much longer: MST circa 500 days

Y4 SA - Oncology (12 decks)

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