Retroperitoneal and Lateral Pelvic Lymph Node Dissection for Colorectal Cancer Metastases

BACKGROUND: Colorectal cancer (CRC) metastases to retroperitoneal (RP) and lateral pelvic (LP) lymph nodes are functionally classified as stage IV disease. While metastasectomy is established for select hepatic and pulmonary metastases, the role of lymphadenectomy for nodal disease remains uncertain. This study evaluates the safety, indications, and oncologic outcomes of RP/LP lymph node dissection in CRC. METHODS: A single-center retrospective review identified patients undergoing RP or LP lymphadenectomy for CRC between 2011 and 2024. Patients with peritoneal metastases or incomplete data were excluded. Demographic, operative, and outcome data were analyzed. Associations with nodal positivity, recurrence-free survival (RFS), and overall survival (OS) were assessed using Fisher's exact test and univariate Cox regression. RESULTS: Forty-nine patients underwent lymphadenectomy, 45% for synchronous and 55% for metachronous nodal metastases. Dissection was selective in 61% and formal in 39%, with 86% undergoing concurrent major abdominal procedures. There was no perioperative mortality and dissection-specific morbidity was low (two lymphatic leaks, both after multivisceral resection). Pathologic nodal metastases were confirmed in 59% of cases. Median RFS and OS were 30.2 and 104.9 months, respectively. Node positivity was associated with initial N2 stage but did not affect RFS or OS. Formal lymphadenectomy was associated with shorter RFS, likely reflecting higher disease burden. CONCLUSIONS: RP and LP lymphadenectomy can be safely performed, even with multivisceral resection. Pathologic nodal status did not predict survival, suggesting potential benefit to lymphadenectomy irrespective of final pathology. These findings support its use in carefully selected patients with controlled systemic disease and isolated nodal recurrence.