V6 - Central versus distal vascular ligation in robotic pelvic lymph node dissection

Purpose/Background: Lateral pelvic lymph node dissection (LPLND) is of paramount importance in rectal cancer especially in cases where lymph nodes persist after neoadjuvant therapy. In locally advanced rectal cancer patients, LPLN involvement is a high risk factor for poor prognosis. Even after neoadjuvant therapy, LPLND reveals positive nodes in 25-50% cases, highlighting its significance.

Methods/Interventions: Our case was a 65 year old gentleman with locally advanced low rectal cancer who had presented with constipation and hematochezia. On evaluation he was found to have large polypoidal growth at 5cm to 15 cm from anal verge on colonoscopy and biopsy revealed moderately differentiated adenocarcinoma. MRI rectum revealed low rectal growth with involvement of anterior peritoneal reflection, right levator and prostate apex and multiple mesorectal nodes, right obturator and external iliac nodes. After multidisciplinary team discussion, in view of cT4aN2M0 disease, he received 2 cycles CAPOX followed by long course chemoradiation and 2 more cycles CAPOX chemotherapy. Response MRI showed partial response and he was planned for robotic total pelvic exenteration with bilateral pelvic lymph node dissection.
In our case, right pelvic lymph node dissection was more challenging compared to left side in view of more bulky nodes along with post radiotherapy changes on right side. Hence we performed central ligation of right internal iliac artery which also helped in enbloc excision of nodal tissue including the nodes at the proximal aspect of internal iliac artery.
On the left side, we performed the standard pelvic nodal dissection and distal ligation of internal iliac artery.

Results/Outcomes: LPLND has significant learning curve and most common intraoperative complication is bleeding. Intra-operatively central vascular ligation on the right side helped in comprehensive nodal dissection and in minimizing blood loss.
Post operatively patient recovered well and had no significant complications.

Conclusion/Discussion: As per our experience, in cases of difficult lateral pelvic nodal dissection in locally advanced rectal cancers post neoadjuvant therapy, central vascular ligation may be a good approach for safe and comprehensive dissection.