V27 - Laparoscopic extra-peritoneal metastatectomy - novel treatment approach to a solitary retroperitoneal colorectal metastasis

CME Eligible

Purpose/Background: Colorectal cancer (CRC) is the third most common malignancy and the second leading cause of cancer-related mortality. Solitary retroperitoneal metastases are typically resected via an intraperitoneal approach posing technical challenges and significant patient-related risks. The extraperitoneal approach is established in other specialties and offers benefits including improved access, avoiding extreme positioning, and reducing small bowel retraction and injury. We report the use of the extraperitoneal laparoscopic approach for excising a solitary retroperitoneal CRC metastasis.

Methods/Interventions: A 58-year old patient post-sigmoid colectomy and end colostomy (T4a, N1b, V1, L1, R2 sigmoid cancer) was treated with adjuvant chemotherapy. Surveillance imaging performed at 9 months identified a solitary, PET-avid retroperitoneal lesion, in close proximity to the left ureter and pelvic side wall. Following discussion at the colorectal MDT, the patient was consented for excision of lesion through an extraperitoneal laparoscopic approach. With the patient in a supine position, a transverse incision was made in the left flank and dissection continued into the pre-peritoneal space. An advanced access platform (GelPOINT Mini) was secured and following insufflation a pneumatic working cavity was created. A 30∘ laparoscope was inserted and the left psoas muscle, gonadal vessels, and ureter easily identified. Dissection began in the retrofascial interface (between Toldt's and Gerota's fascia), continuing caudally and medially based on the lesion's CT location.

Following positive identification of the left ureter, an advanced energy device was used to resect the target lesion achieving complete excision.

Results/Outcomes: The patient made an uneventful post-operative recovery and following a several day hospital stay was subsequently discharged with clinic follow-up.

Conclusion/Discussion: Laparoscopic surgery is safe with comparable oncological outcomes and well-established benefits including reduced post-operative pain, analgesic requirement, earlier mobilization, and shorter hospital stays. However, challenges arise in high-risk patients (high BMI, prior surgery, severe cardio-respiratory conditions) due to difficulties with safe access, visualization, and the inability to use extreme patient positioning required for optimal views.

We propose the extraperitoneal approach as a safe and feasible alternative, although it has a steep 'learning curve'. Its main value is improved appreciation of key anatomical landmarks (ureter, retroperitoneal fascia, vascular structures) and their preservation, potentially reducing complications compared to breaching the peritoneum.

Extreme positioning in conventional laparoscopy can be detrimental for patients with severe COPD, risking reduced lung capacity, atelectasis, and ventilation-perfusion mismatch, alongside rare but serious complications like brachial plexus injury or optic neuropathy. The extraperitoneal approach avoids the need for positional change and small bowel retraction, allowing for precise dissection and reducing the risk of inadvertent injury/bleeding from mesenteric countertraction.

The extraperitoneal approach supported by cadaveric experience for right-sided colonic resections, is a promising novel procedure that can be safely adapted clinically to potentially improve patient outcomes and prevent rare complications. However, further work is required to assess its safety and feasibility.