Comparison of Mayo and Milwaukee Risk Stratification Models for Predicting Lymph Node Metastasis in Endometrial Cancer

Objective The aim of this study was to compare Mayo and Milwaukee risk stratification models for predicting lymphatic dissemination in patients with endometrial cancer (EC). Methods A total of 904 patients with EC underwent surgical treatment between 2004 and 2016 at Hacettepe University Hospital, and clinicopathological data of patients were retrieved from the computerized database of the Hacettepe University. Patients who did not undergo lymphadenectomy and who had nonendometrioid histology, stage-IV disease, and synchronous epithelial ovarian and EC were excluded. All slides of the cases were reviewed by the same gynecologic pathology subspecialist. Results The study group consisted of 307 consecutive patients with a mean age of 59.4 years (range, 26-86 years). Lymph node metastasis was detected in 28 subjects (9.1%). Primary tumor diameter, depth of myometrial invasion, lymphovascular space invasion, and cervical stromal and glandular involvement were associated with lymph node metastasis. Patients with low-risk histological features based on Mayo risk stratification system in our study group had a 0% rate of lymph node positivity. However, of the 28 patients with lymph node metastasis, 3 (10.7%) had low-risk features based on Milwaukee model. The sensitivity, specificity, false negative rate (FNR) and false positive rate of Mayo and Milwaukee risk stratification models for predicting lymphatic dissemination among women with endometrioid EC were 100%, 27.3%, 0%, and 72.7%; and 89.3%, 61.3%, 10.7%, and 38.7%, respectively. Conclusions Although Milwaukee risk stratification model had a lower false positive rate and can decrease the number of lymphadenectomies, FNR of this new model was found as 10.7% in the present study. Furthermore, we found that Mayo model had a lower FNR and higher sensitivity. Therefore, Mayo model still looks more beneficial to predict lymph node metastasis in patients with endometrioid EC and Milwaukee risk stratification model still requires external validation.