Distribution of Lymph Node Metastasis Sites in Endometrial Cancer Undergoing Systematic Pelvic and Para-Aortic Lymphadenectomy: A Proposal of Optimal Lymphadenectomy for Future Clinical Trials

Purpose The aim of this study was to demonstrate the precise mapping of lymph node metastasis (LNM) sites in endometrial cancer. Methods A total of 266 patients who underwent primary radical surgery including systematic pelvic and para-aortic lymphadenectomy for endometrial cancer from 1993 to 2010 were enrolled in this study. We removed lymph nodes from the femoral ring to the para-aortic node up to the level of renal veins. We analyzed the distribution of positive-node sites according to their anatomical location. Results Overall, 42 of 266 patients (15.8 %) showed LNM. The median number of nodes harvested was 62.5 (range 40–119) in pelvic nodes (PLN), and 20 (range 3–47) in para-aortic nodes (PAN). Among 42 cases with positive-nodes, 16 cases (38.1 %) showed positive PLN alone, 7 cases (16.7 %) in PAN alone, and 19 cases (45.2 %) in both PLN and PAN. The most prevalent site of positive-nodes was PAN (9.8 %) followed by obturator nodes (9.4 %), internal iliac nodes (7.1 %), and common iliac nodes (5.6 %). Six of 19 cases (31.6 %) of positive PAN above the inferior mesenteric artery (IMA) showed negative PAN below IMA. Metastasis to the deep inguinal nodes was found to be extremely rare (0.38 %). Single-site LNM was the most frequently observed in obturator nodes, followed by PAN above IMA. Conclusion Routine resection of deep inguinal nodes is not recommended, whereas para-aortic lymphadenectomy should be extended up to the level of renal veins for endometrial cancer.