Pre-TME era
Mesorectal subsite / LN region
Mesorectal subsite/LN ALWAYS included in CTV
Lateral pelvic subsite / LN region
Cranial: bifurcation common iliac arteries
Caudal: level were obturator artery enters obturator canal
Anterior: ureter
Includes LN along pelvic side wall:
internal iliac artery + middle rectal artery +/-obturator artery
Lateral pelvic subsite / LN region
Lateral subsite/LN ALWAYS included in CTV
Lateral pelvic subsite / LN region
0% (0/133)
3% (3/99)
9% (33/373)
Obturator nodes ONLY included in CTV
If Tumor < 10 cm
Steup et al (EJC,2002): LN along the obturator artery
Posterior pelvic subsite
Presacral space
Includes LN along sacral vessels, inferior hypogastric plexus
Posterior pelvic subsite
Posterior subsite ALWAYS included in CTV
Inferior pelvic subsite
triangle of the perineum containing
sfinctercomplex
perianal/ ischiorectal space
Discussion inferior pelvic subsite
Inferior pelvic subsite
APR: 11 %
ALWAYS include in CTV
T< 6 cm: 8 %
T> 6 cm : 3 %
T>11 cm: 0%
NOT include in CTV
Low Risk locations for local failure
Anterior pelvic subsite
Includes all organs ventrally of the mesorectal subsite
Anterior pelvic subsite
Anterior subsite ONLY included in CTV
if invasion anterior organ (prostate, bladder,…)
External iliac + inguinal LN
External iliac LN ONLY included in CTV
If anterior organ invasion
Inguinal LN ONLY included in CTV
If massive invasion anal margin
If invasion lower third vagina
Discussion External iliac LN
45 patients with T4 rectal cancer
preoperative CRT without elective external iliac node RT
no recurrences in external LN region!
Sanfilippo et al, Int J Rad Onc Biol Phys 2001
Upward LN region
Includes inf. mesenteric artery +/- sup. rectal artery
Upward LN region NOT included in CTV
because….
Upward LN region
□ No sign. difference in survival !
□ Not sign. more diarrhea
□ Sign. more hematological and
liver complications.
Delineation clinical target volume
All patients :
CTV = Posterior PS + Mesorectal PS/LN + Lateral PS/LN
□
□
□
□
□
+/Inferior PS: tumor < 6 cm from anal margin +/- APR
Obturator LN: tumor < 10 cm from anal margin
External iliac LN tumor invades anterior organ
Anterior PS
Inguinal LN: tumor invades lower third vagina or
massive anal invasion
Delineation clinical target volume
Consensus on clinical target volume regions
BUT…
No Consensus on anatomical borders !
Atlas for pelvic LN delineation
Can we use pelvic blood vessels as a surrogate for delineation
of
lymph node regions?
Goal + Methods
GOAL
to map pelvic normal LN
to determine appropriate margins around blood vessels to
cover LN
METHODS
20 patients with gynaecologic tumors
MRI
MRI + USPIO
Pelvic nodes contoured on USPIO MRI
Margins of 3, 5, 7, 10 and 15 mm around blood vessels
5 CTV’s
Results
Modified 7 mm margin: 99% LN covered
100% coverage of internal iliac LN:
lateral border enlarged to pelvic sidewall
99% coverage of obturator LN:
width of 18 mm along the pelvic sidewall
presacral LN:
too few nodes to draw conclusions
Remaining problem
Anterior border of the obturator LN region ?
common iliac a.
external iliac a.
obturator a.
internal iliac a.
Remaining problem
Delineation of all internal iliac branches in the pelvis ?