Kilts, Toni P.

INTRODUCTION: To compare two published risk stratification criteria (Milwaukee Model vs. Mayo Criteria) to predict lymphatic dissemination (LD) in endometrioid endometrial cancer (EC). METHODS: Patients who underwent surgery for EC between 1/1/2004-9/30/2013 and had endometrioid histology without stage IV disease were included and classified as either low-risk or at-risk for LD using two independent risk stratification systems. LD was defined as positive nodes at time of surgery or lymph node recurrence within 2 years of surgery after negative lymph node assessment (LNA) or when LNA was not performed. False positive (FP) and false negative (FN) rates for each risk model were calculated. RESULTS: Among 1103 patients, 81 (7.3%) had LD (72 positive LN and 9 LN recurrences). Most patients (90.2%) had stage I disease. Integration of the Milwaukee Model was associated with a low at-risk rate for LD (38.1%) but a relatively high FN rate (13.6%, 95% CI 7.0-23.0). Conversely, the traditional Mayo Criteria using a tumor diameter (TD) cutoff of ≤2 cm (vs >2 cm) had a higher at-risk rate for LD (69.5%) but a FN rate of 0.0% (95% CI, 0-4.5). Modifying Mayo Criteria using a TD cutoff of ≤3 cm (vs >3 cm) identified fewer women at-risk than using ≤2 cm cutoff (56.8% vs. 69.5%), but had a higher FN rate of 3.7% (95% CI, 0.8-10.4). CONCLUSIONS: The Milwaukee Model had the lowest at-risk rate of LD but an unacceptable FN rate. Modifying the Mayo Criteria by increasing the TD cutoff from the traditional ≤2 cm to ≤3 cm would spare an estimated 12.7% of patients LNA, but the accompanying FN rate is unacceptably high. The traditional Mayo Criteria for low-risk EC remains the most accurate in determining which patients LNA can be omitted.