Analysis of A Single Para-Aortic Lymph Node Metastasis in Endometrial Cancer

Objective: To determine the indication for lymph node dissection in patients with endometrial cancer, we investigated the incidence and distribution of single metastatic lymph nodes in patients who underwent systematic pelvic and para-aortic lymph node dissection.Methods: This study involved 910 patients with endometrial cancer who were treated at the Cancer Institute Hospital, Japan, between January 1994 and December 2015. All patients underwent an open hysterectomy with bilateral salpingo-oophorectomy and pelvic and para-aortic lymph nodes dissection.Results: Lymph node metastasis was observed in 199 patients (21.9%), 45 (5%) of whom had single lymph node metastasis. Single lymph node metastasis accounted for 22.6% of all metastatic cases. Myometrial invasion >50% was observed in 30 patients, whereas 15 patients had <50% myometrial invasion. When mapping single lymph node metastatic sites, the para-aortic area had a frequency of 31.1% (14 cases). The distribution of single metastatic lymph nodes spanned a wide area between the pelvic and para-aortic regions. Considering single metastatic nodes and myometrial invasion, 8 patients (53.3%) who had myometrial invasion <50% had a single metastatic node in the para-aortic region. Four of 9 patients (45%) considered low-risk (endometrioid Grade 1-2, invasion depth <50%, no lymphovascular space invasion) showed metastasis to the para-aortic areas.Conclusion: Single metastatic lymph nodes were widely distributed between the pelvic and para-aortic regions, suggesting that detection of a sentinel lymph node in patients with endometrial cancer could be problematic.