Assessing Preoperative Grading Discrepancies in Endometrial Cancer: Impact of Biopsy Method and Clinical Risk Factors

Although molecular classification has improved risk stratification in endometrial cancer (EC), preoperative surgical decision-making remains based on histological subtype and tumor grade. We compared the diagnostic concordance of Pipelle biopsy and dilation and curettage (D&C) with final pathology in EC and identified risk factors for postoperative pathological discrepancies following Pipelle biopsy.

We retrospectively analyzed 355 patients with EC who underwent preoperative endometrial sampling by D&C or Pipelle biopsy between January 2009 and December 2025. EC was categorized according to the WHO 5th edition as low-grade (G1/G2 endometrioid endometrial carcinoma [EEC]), high-grade (G3 EEC), or non-endometrioid carcinoma (NEEC). Postoperative upgrading was defined as low-grade to high-grade/NEEC, and downgrading as high-grade/NEEC to low-grade. Concordance between preoperative and final pathology was assessed using Cohen's kappa coefficient. Binomial logistic regression analysis was performed in 297 patients with available clinical data to identify factors associated with pathological discrepancy.

D&C demonstrated almost perfect concordance with final pathology (κ = 0.846), whereas Pipelle biopsy showed moderate concordance (κ = 0.577; p < 0.05). In the Pipelle group, endometrial thickness on MRI and preoperative histology were independently associated with pathological discrepancies. Patients with G1 EEC and endometrial thickness > 4.00 cm, and those with G2, G3, or NEEC and thickness > 0.40 cm, had a significantly increased risk of discordance.

Diagnostic concordance was higher for D&C than for Pipelle biopsy. In selected high-risk patients, particularly those with higher-grade histology or increased endometrial thickness, D&C may be considered to improve preoperative pathological assessment and support surgical decision-making.