IMRT for Endometrial Cancer

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IMRT for Endometrial Cancer Contouring Session
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Classic Fields Arrangement
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Aims of IMRT

• Treat the nodal areas at risk
• Surgery already dealt with the primary
• Spare the organs at risk
• Small bowel
• Rectum
• Bone marrow
• Bones
• Bladder

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Voluming of CTV

• The lymph node areas follow the pelvic vessels
• Internal iliac
• Common iliac
• Part of the external iliac chain
• Presacral nodes
• Nodes at bifurcation of the abdominal aorta
• Margins for PTV from CTV 1cm -1.5cm

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Dose Aim

• 45Gy in 25 fractions
• Some newer protocols (PORTEC) use 48.6Gy in 28
  fractions

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Upper Aspect
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Upper Middle Aspect
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Middle Lower Aspect
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Lower Aspect
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Upper Vagina
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Contouring of the small bowel

• Contour the small bowel en block
• There always will be some overlap with PTV
• Normal prescription tolerance 36Gy
• Allowed dose 42.75Gy 95 of the 45Gy
• (the prescribed dose)

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Small bowel
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Contouring of the Bladder

• Full vs. Empty bladder
• Empty bladder is easier to reproduce on daily
  basis
• Significant overlap with PTV
• Tolerance prescription dose 36Gy
• Max allowed dose 42.75Gy

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Contouring of the Bladder
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Contouring of the Bone Marrow

• Most controversial part of IMRT planning
• Traditionally tolerance quoted 4Gy
• Never really achievable even with IMRT
• Clear experimental data for lower marrow toxicity
  even with high dose limits e.g. 35Gy

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Bone Marrow Sparing

• Especially important if chemotherapy is given
• Any dose limitation is of benefit

p0.79
p 0.08
Brixey et al.,Int J Radiat Oncol Biol Phys. 2002
Dec 154(5)1388-96.
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Bone Marrow Contouring
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Contouring of the Rectum

• From the anal canal to the rectosigmoid junction
• Uterosacral ligament attaches at S2-3
• There is no need the posterior rectum to received
  the full dose below S3

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Contouring of the Rectum
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The Plan
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The Patient for Today

• 64 year old lady
• 6mo history vaginal bleeding
• Hysteroscopy and curettage
• Endometrial carcinoma, Grade 3
• TAH and BSO
• Grade 3 endometrial adenocarcinoma
• Infiltration gt50 of the myometrium
• Lymphovascular invasion - present
• No cervical involvement
• Several lymph nodes sampled - negative

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Treatment issues

• To irradiate or not
• Total dose and dose to critical structures
• Patient positioning
• Role of chemotherapy
• Extend of the treatment fields
• Expected side effects