Impact of preserving circumflex iliac nodes distal to the external iliac nodes (CINDEIN) on prognosis in low-risk endometrial cancer patients

Aim Sentinel lymph node (SLN) mapping has become the standard approach for lymph node (LN) assessment in patients with low-risk endometrial cancer (EC). However, until its coverage by the Japanese national health insurance system in 2025, pelvic lymphadenectomy (PLA) had been routinely performed for nodal assessment in Japan. The resection of circumflex iliac nodes distal to the external iliac nodes (CINDEIN) in PLA is associated with an increased risk of lymphedema. CINDEIN preservation in EC patients reduces the risk of lymphedema; however, the impact of CINDEIN preservation on recurrence patterns and prognosis is unclear. Therefore, we herein examined the effects of CINDEIN preservation on recurrence patterns, survival outcomes, and lymphedema in patients with low-risk EC. Methods We retrospectively analyzed 65 patients with preoperatively diagnosed low-risk EC who underwent PLA as their initial treatment between January 2016 and December 2024. Patients were divided into two groups according to whether CINDEIN was resected or preserved, and treatment effects and prognosis were evaluated. Results: Lymphedema was noted in 1 case in the CINDEIN-preserved group (2.7%) and in 7 in the CINDEIN-resected group (25%), demonstrating a significant difference ( P = 0.017). Recurrence was noted in 4 cases in the CINDEIN-preserved group and in 2 in the CINDEIN-resected group ( P > 0.05). There were no significant differences in PFS or OS between the two groups. Conclusions CINDEIN preservation may be performed on patients with low-risk EC without worsening their prognosis and correlated with a reduced risk of lymphedema.