Objective: To compare two published risk stratification models (Milwaukee Model vs. Mayo Criteria) to predict lymphatic dissemination (LD) in endometrioid endometrial cancer (EC).
Methods: Patients with stage I-III EC undergoing surgery from 1/1/2004-9/30/2013 were retrospectively reviewed and classified as low-risk vs at-risk for LD using two independent risk models. LD was defined as positive nodes at surgery or lymph node recurrence within 2 years of surgery after negative lymph node dissection (LND) or when LND 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), and most (90.2%) had stage I EC. The Milwaukee Model yielded a low at-risk rate for LD (38.1%) but a high FN rate (13.6%, 95% CI 7.0-23.0). The traditional Mayo Criteria using a cut-off of 2 cm for tumor diameter (TD) had a higher at-risk rate for LD (69.5%) but a FN rate of 0% (95% CI, 0-4.5). Modifying the Mayo Criteria using a TD cutoff of ≤3 cm identified fewer women at-risk (56.8% vs. 69.5%) and had a lower FP rate (53.6% vs. 67.1%), but had a higher FN rate (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 13.5% of patients LND, but the accompanying FN rate is unacceptably high. The traditional Mayo Criteria for low-risk EC remains the most sensitive in determining which patients LND can be omitted.
Keywords: Endometrial cancer; Tumor diameter; Tumor grade.
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