Surgical Management of Endometrial Intraepithelial Neoplasia at Military Treatment Facilities: A Multicenter Retrospective Study

Introduction Endometrial intraepithelial neoplasia (EIN), also known as atypical endometrial hyperplasia (AEH), is a precursor lesion of endometrial carcinoma (EC). In endometrial cancer patients, lymph node assessment with biopsy during hysterectomy is part of surgical staging. However, routine lymph node assessment for EIN is inconsistently utilized. This study aims to investigate the surgical management of EIN in the military to inform best-practice guidelines tailored for the Military Health System to avoid delays in care, manage cost, ensure military readiness and optimize clinical outcome. Materials and Methods We performed a retrospective chart review of patients with EIN treated at 2 military treatment facilities over a 10-year period between July 1, 2013 and July 1, 2023. Pathology reports were queried to identify patients with a preoperative diagnosis of EIN. Patients not surgically managed were excluded. Statistical analysis was performed using chi-squared test and Wilcoxon rank-sum test. Independent associations were investigated using logistic regression modeling. Results There were 95 evaluable patients with an EIN diagnosis, including 43 (45.3%) patients upstaged to EC based on final pathology (95% CI: 35.0-55.8). Older patients diagnosed with EIN ≥65 years old and those with endometrial thickness ≥15 mm exhibited the highest risk for upstaging EIN to an EC diagnosis. Of the 50 patients who underwent lymph node assessment, none had positive lymph nodes. Patients diagnosed with EIN via hysteroscopy vs. an endometrial biopsy had the lowest risk of being upstaged to EC. Conclusions Upstaging from EIN to EC occurred in 45.3% of the 95 patients emphasizing the value of performing surgicopathologic staging in this setting. In contrast, none of the 50 EIN patients who underwent lymph node resection had positive lymph nodes indicating morbidity risk with low likelihood of clinical benefit. We identified risk factors for upstaging to EC, including age ≥65 years and endometrial thickness ≥15 mm, and confirmed the diagnostic superiority of hysteroscopy. These findings have informed clinical practice guideline recommendations for the surgical management of EIN in the Military Health System.