Sampling Method Influences Endometrial Cancer Risk and Sentinel Lymph Node Planning in Patients With EIN

A retrospective analysis of 266 patients with a preoperative diagnosis of endometrial intraepithelial neoplasia (EIN) showed that the likelihood of detecting endometrial cancer (EC) on final hysterectomy pathology varied significantly by sampling method. Patients diagnosed with EIN via blind endometrial biopsy (EMBx) had a higher rate of EC on final pathology (48%) compared with those diagnosed via hysteroscopy with dilation and curettage (HSC/D&C; 27%) (P < .01). Researchers presented their results at the Society of Gynecologic Oncology 2025 Annual Meeting on Women’s Cancer in Seattle, WA.

EIN is a known precursor to endometrioid EC, and historical data have estimated a 30% to 40% risk of underlying malignancy at hysterectomy. However, previous studies have not accounted for differences in diagnostic sampling methods, which can affect preoperative counseling and surgical decision-making, particularly regarding sentinel lymph node mapping at the time of hysterectomy.

This retrospective cohort study included patients from two institutions who underwent hysterectomy for EIN between 2011 and 2023. All pathology specimens were reviewed by gynecologic pathologists. Patients were stratified based on sampling method—either EMBx or HSC/D&C. The presence of EC on final pathology and the presence of high-risk features (those who did not meet Mayo criteria for omitting lymph node assessment) were analyzed using χ² and Fisher exact tests.

Of the 266 patients included, 106 (40%) were diagnosed via EMBx and 160 (60%) via HSC/D&C. Demographic characteristics including age, body mass index, and self-reported race and ethnicity did not significantly differ between groups.

EC was identified in 96 patients (36.1%), with a significantly higher detection rate in the EMBx cohort compared with the HSC/D&C cohort (48% vs 27%, P < .01). High-risk features among those diagnosed with EC were also more prevalent in the EMBx group (41% vs 20%, P ≤ .05). When evaluating the entire study population, 20% of patients in the EMBx group had EC with high-risk features, compared with just 5% in the HSC/D&C group (P = .001).

“Our study demonstrates that in patients with a preoperative diagnosis of EIN, there was a statistically significant higher rate of malignancy detected if the diagnosis was made by EMBx compared to HSC/D&C,” the authors concluded.

Reference
Kar A. Incidence of endometrial cancer by preoperative sampling method in endometrial intraepithelial neoplasia and impact on surgical management. Paper presented at: Society of Gynecologic Oncology 2025 Annual Meeting on Women’s Cancer; March 14-17, 2025; Seattle, WA. Accessed March 11, 2025