Extended lymph node dissection for rectal cancer with radiologically diagnosed extramesenteric lymph node metastasis

Background: The purpose of this study is to review the clinical outcomes of patients who received extended lymph node dissection for radiologically diagnosed extramesenteric lymph node metastasis. Patients and Methods: The authors reviewed clinical characteristics, short-term operative outcomes, and long-term oncologic outcomes of 151 patients who had received total mesorectal excision plus extended lymph node dissection for the treatment of radiologically diagnosed extramesenteric lymph node metastasis. Results: The positive predictive value of the radiologic diagnosis of extramesenteric lymph node metastasis was 86.4% for lateral nodes and 40.0% for para-aortic nodes. It showed improvement over time. Perioperative mortality occurred in 3 patients (2.0%) and morbidity in 31 patients (20.5%). Pathologic examinations revealed metastatic para-aortic lymph nodes in 43 patients (PA) and metastatic lateral pelvic nodes in 36 patients (LP), while in 21 patients, metastasis was found in both (LP + PA). Both cancer-specific survival (CSS) and disease-free survival (DFS) were significantly different according to the extent of node metastasis (CSS: P < .001; DFS: P < .001) and univariate and multivariate analyses for prognostic factors revealed that the lymph node status as to location was the only factor. Conclusion: Patients with extramesenteric lymph node metastasis may be a distinct subgroup with poor prognosis. Extended lymph node dissection may have a role for those patients. However, the optimal treatment strategy remains inconclusive, for which further clinical research is necessary.