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radiation therapy in practice > Sarcoma > Flashcards

Sarcoma Flashcards

1
Q

what are the two broad categories of sarcoma

A

soft tissue sarcoma (80%)
bone sarcoma (20%)

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2
Q

classification of sarcoma

A
  • numerous different types
  • various tools used to define them
    biological behaviour
    tissue of origin
    grade
    frequently require review by international specialists
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3
Q

sarcoma location

A

9% H&N
25% GI tract
15-20% retroperitoneum/intra-abdominal
60% arms or legs

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4
Q

risk factors

A
  • probably arise de novo
  • multifactorial including exposure to radiation, chemotherapy, carcinogens, chronic lymphoedema, HIV/HSV8 (Kaposi’s), around 10% genetic
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5
Q

clinical presentation

A
  • usually slow growing painless lumps
  • mean time before attending GP 4 months
  • symptoms related to site of tumour
  • metastases unusual at presentation
    can be very easily mistaken for number of non-cancerous conditions
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6
Q

warning signs that a lump in soft tissue might be a sarcoma

A
  • measures >4cm - the side of a golf ball
  • is getting bigger
  • lies deep to fascia
  • is non tender (but pain occasionally)
  • is in the leg, arm or back
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7
Q

spread of sarcoma

A

direct
- occasionally with skip areas
- generally extend along tissue planes

regional LN
- involvement infrequent
- around 5-10% (1st site of metastases) except rhabdomyocin sarcoma, epithelioid sarcoma, vascular sarcomas
- more common with increasing grade: G1 0%, GII 2.5%, GIII 12%

direct metastases
- uncommon at presentation
- often present later in disease course - related to grade and size of tumour
- 1st site usually lung (70-80%)

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8
Q

diagnosis

A
  • complete history and physical examination
  • bloods: FBC, U/E, LFT
  • Biopsy
    -> crucial
    -> incisional (open), core, FNA or exceptionally total excision
    -> must be performed by experienced surgeons
    -> must be carefully planned - to be incorporated within later operative bed
  • Imaging
    -> plain films, ultrasound, MRI (soft tissue extent) and CT (bone destruction, lymph nodes)
    -> CT thorax
    -> role of PET/CT is unclear
    -> bone scan is not usually helpful for initial staging (except primary bone tumours)
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9
Q

staging

A

AJCC 6th Edition (2002)
T1 <5cm a - superficial, b - deep
T2 >5cm a- superficial, b - deep

stage IA/B | T1a-b T2a-b | Grade 1-2
stage IIA/B | T1a-b T2a | Grade 3
stage III | T2b | Grade 3

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10
Q

poor prognostic factors

A

for local stage:
- increased size of tumour
- deep vs superficial location
- high grade
- symptoms at presentation
- retroperitoneum vs extremities
- R1-2 (micro/macro incomplete) vs R0 (complete) resection
- increased age of patient

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11
Q

Treatment

A

surgical resection is only potentially curative therapy
- sole treatment for superficial low grade tumours <= 5cm
- aims of surgery: total en bloc excision of 1deg without cutting through tumour
- most important surgical variable that influences local control is presence or absence of tumour cells at surgical margin
- occasionally amputation is only option

RT and chemo (given before or after surgery) are aimed at:
1. marking a sarcoma easier to remove
2. reducing the risk of the sarcoma coming back in the area it started
3. reducing the risk of the sarcoma travelling to other organs

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12
Q

palliative treatment

A
  • when a sarcoma is not curable and the aim of treatment is to alleviate the symptoms it is causing
  • most frequently achieved by:
    RT
    chemo
    non-chemo medication
    psychological support
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13
Q

impact of RT

A
  • reduces risk of local relapse
  • no impact on survival
  • QoL and limb function depend on good local control
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14
Q

role of RT

A

adjuvant RT improves local control
- Yang (1998) 141 Pts EBRT vs no EBRT (64% high grade). HG LR 0% vs 22% (p = 0.0001). LG LR (p = 0.003)
- Pisters (1996) 164 Pts Brachy vs none. LR 18% vs 31% at 5 years (p=0.04)
permits limb sparing

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15
Q

indications for RT in localised soft tissue sarcoma

A
  • intermediate and high grade tumours
  • tumour >= 5cm
  • deep tumours (deep to fascia)
  • ‘close’ resection margins
  • microscopically positive resection margins, if further surgery not possible
  • low grade tumours, if marginally resected and further resection at relapse will be difficult
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16
Q

timing of RT

A
  • given alone
    palliation (inoperable)
    occasionally -> long term control
  • pre-op
    5 weeks treatment centred on gross tumour
  • post-op
    6-6.5 weeks treatment
    2 phases
    need to treat operative bed
17
Q

RT scheduling (pre vs post-op)

A

only one randomised phase III trial (O’ Sullivan 2002)
190 Pts. median follow up 6.9 years. pre-op 50Gy/25# (+16Gy boost if margin +ve) vs, post-operative (66Gy/33#)
1st end point: wound complication rate
2nd end point: late complications/function/QoL

  • no difference in LR, regional/distant failure rate, PFS
  • trial closed before completion
    -> wound complication rate in pre-op arm (35% vs 17%)
    -> lower extremity > upper (43% vs 5%)
  • increased late effects in post-op arm
    -> tissue oedema/fibrosis
    -> impaired function
    -> fractures
18
Q

target volume (pre-op)

A

Single phase (50Gy/25#)

Proximal/distal margins: 2-4cm proximal and distal to site of disease

radical margins: 2cm or up to bone, interosseous membrane, major fascial plane
aim to spare corridor (around 1/3 limb circumference) of normal tissue (lymphatic drainage)

GTV defined using T1W MRI but with oedema included (T2W images)

19
Q

RT target volume (post-op)

A

Phase I (50Gy/25#/5 weeks)

proximal/ distal margins: >= 4cm proximal and distal to site of original disease - ideally to include scar/drain sites i.e. potential sites of contamination

radical margins: 2cm or up to bone, interosseous membrane, major fascial plane
>2cm if plane has been violated
aim to spare corridor of normal tissue (lymphatic drainage)

Phase II (10-16Gy/5-8#/1-1.5 weeks)

proximal/distal margins: >= 2cm proximal and distal to site of original disease

radical margins: 2cm or up to bone, interosseous membrane, major fascial plane
>2cm if plane has been violated
aim to spare corridor of normal tissue (lymphatic drainage)

20
Q

late normal tissue toxicity

A

subcutaneous fibrosis
joint
oedema
generally all greater in post-op arm compared to pre-op complications

21
Q

RT-induced bone fractures

A
  • morbidity significantly higher than normal fracture (around 20%)
  • lower limb > upper limb
  • delayed union
  • multiple operations
  • increased infection rate
    –> endoprosthetic replacement or amputation
  • limited RT dose volumetric data
22
Q

late bone toxicity

A

retrospective Princess Margaret Hospital study (Dickie 2009) (6% fracture rate)
21 patient plans (24 fractures) treated 1995-2004
matched (2:1) to non-fracture cohort
risk of radiation induced fracture significantly reduced if:
- maximum dose <60Gy
- mean dose <38Gy
- % of bone irradiated to >=40Gy is <66%

23
Q

minimising toxicity

A
  • optimising volume increasing conformality
  • role of IMRT
    -> offers potentially less normal tissue morbidity
    -> two recent prospective phase II trials: RTOG 0630 trial (Wang 2011), Princess Margaret Hospital trial (Dickie 2010)
    -> both specifically assess effect of IMRT on the reduction of late toxicity
  • optimising volume - better immobilisation
    -> customised device
24
Q

summary

A
  • RT decreased LR if given before/after limb sparing surgery soft tissue sarcomas
  • late normal toxicity has significant impact on QoL
  • minimising irradiated volume essential: conformal techniques, clinical trials, better immobilisation
25
Q

Gastrointestinal stromal tumour (GIST)

A
  • most common sarcoma (18%)
  • ages 40-80
  • incidence around 12 per million
  • stomach and small intestine most common sites
  • originates from the Interstitial cells of Cajal
  • surgery is the only curative therapy
  • Adjuvant Imantinib
    -> reserved for high risk cases (location, mitosis, size, grade)
26
Q

Retroperitoneal sarcoma

A
  • 15-20 cases per year in Ireland
  • usually low grade liposarcoma
  • often require multi-visceral resection
  • require specialised centres (>12 cases/year)
  • RT may minimised risk of LR especially for liposarcomas - best given pre-operatively
  • no proven role for chemo (excluding in certain sub-types)
27
Q

gynaecological sarcomas

A
  • low/high grade endometrial stromal sarcoma
  • leiomyosarcoma
  • adenosarcoma
    total hysterectomy +/- bilateral salpingo-oopherectomy is standard
    role of adjuvant therapies uncertain
28
Q

thoracic/paraspinal/trunk/H&N

A
  • surgery
  • +/- RT
  • role of chemo unproven
29
Q

Bone sarcomas

A
  • osteosarcoma
  • Ewing’s sarcoma
  • chondrosarcoma
  • chordoma
30
Q

osteosarcoma

A
  • usually arise in long bones (often around knee)
  • involvement of axial skeleton and craniofacial bones - primarily in adults
  • multiagent chemo + surgery dominate therapy

RT
- relatively radioresistant
- only considered if tumour is unresectable or incompletely (R2) resected
- but might change with increasing availability of IMRT/protons, small cell osteosarcoma, patient refuses surgery, palliation

31
Q

Ewings

A
  • chemo and radio sensitive
  • peak age 10-20 years
  • 80-90% receiving local therapy alone relapse
  • intensive multiagent chemo is SoC and has dramatically increased survival

RT - local control
localised disease
- surgery or RT provide effective LC
- surgery - preferred if lesion seems resectable with negative margins and without excessive morbidity
- if no function-preserving surgical option because of location (e.g vertebra/pelvis) or extent then RT used

RT - post-op
indications not firmly established but considered in:
- bulky tumours in difficult sites (e.g. pelvis) - pre or post-op
- residual (unintentional) microscopic, gross disease or inadequate surgical margins (marginal or intralesional resection)
- significant viable tumour (>10%) in resected specimen following NA chemo and less than wide surgical margins

32
Q

chondrosarcoma

A
  • age 30-60 years
  • most common bone sarcoma in adults
  • site: centrally in diametaphyses of long bones, but also pelvis, rib and scapula

RT
- surgery dominates management
- optimal is R0 resection
- notoriously chemo and radio resistant but institutional series report excellent outcomes when RT is given adjuvantly (following marginal or intra-lesional surgery) or in irresectbale sites - high doses (>60Gy) and highly conformal
- 80-90% local control rates

33
Q

chordomas

A
  • sacrum or skull base
  • high dose RT using proton beams or carbon ion therapy
34
Q

summary

A
  • uncommon tumours
  • curative treatment may involve surgery, RT and/or chemo depending on the histological sub-type and tumour location
  • most are cured - especially if diagnosed easily
  • when indicated RT requires complex planning
  • best outcomes are in specialised centres

radiation therapy in practice (19 decks)

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