Incidence of Lymph Node Metastasis in Patients With a Preoperative Diagnosis of Endometrial Intraepithelial Neoplasia.

Introduction: Endometrial cancer is the most common gynecologic cancer in the United States, and endometrial cancer staging historically has included lymph node assessment to inform prognosis and guide recommendations for adjuvant treatment. This study sought to determine the incidence of lymph node involvement in patients undergoing hysterectomy with sentinel lymph node dissection for a preoperative diagnosis of endometrial intraepithelial neoplasia (EIN) to allow for risk stratification and management by general gynecology and gynecologic oncology.

Methods: We performed a retrospective chart review of patients diagnosed with EIN who underwent hysterectomy from January 2018 through July 2021. We collected and analyzed patient characteristics, perioperative metrics, and postoperative data. Incidence of lymph node positivity on final pathology was the primary outcome of interest. We analyzed clinical and histologic risk factors for correlation with a final diagnosis of endometrial carcinoma. Chi-square, Fisher exact, and t tests were used for comparisons.

Results: One hundred patients met inclusion criteria, 40 of whom had an underlying endometrial cancer. The majority were stage IA grade 1 endometrioid carcinomas (95%). Per institutional protocol, all patients were recommended sentinel lymph node dissection, of which 84 (84%) patients ultimately underwent lymph node dissection. One patient was found to have a positive sentinel lymph node on final pathology (1.2%). Increasing endometrial stripe thickness was positively associated with risk of endometrial carcinoma on final pathology (22.39 mm ± 31.87 vs 11.78 mm ± 5.17, P = 0.023).

Conclusions: The incidence of lymph node involvement in patients with a preoperative diagnosis of EIN is low. Sentinel lymph node dissection is unlikely to affect adjuvant treatment recommendations following surgical staging. Standardized risk assessment methods are warranted for patients with a preoperative diagnosis of EIN to delineate the utility of lymph node assessment in this population.