Lymphovascular Space Invasion (LVSI)-Based Prognostic Clusters in Endometrial Cancer Patients Treated with Primary Surgery and Adjuvant Radiotherapy

Objectives To investigate prognostic clustering based on lymphovascular space invasion (LVSI) in relation to histological prognostic factors in endometrial cancer patients through patterns of failure and survival. A secondary objective was to develop iso-prognostic clusters of low-, intermediate- and high-risk patients . Methods and Materials Patients with traditional intermediate, intermediate-high and high-risk endometrial cancer treated with primary surgery and staged as 1 to 3C, presented for adjuvant radiotherapy treatment sequentially between 1996 and 2014, were analysed (n = 1187). Histology included was endometrioid/mucinous, clear cell and serous. Distinct prognostic clusters were identified based on recurrence-free and overall survival (OS) using Cox proportional hazard models and Kaplan-Meier technique. Results Median follow-up period for the entire cohort was 5.4 (3.6-8.6) years. In the absence of LVSI and positive nodes, histology, grade, myometrial invasion and tumour size had no prognostic significance. LVSI was related to histology grade and lymph-node metastasis. The ratio for LVSI to lymph-node metastasis was 3:1 except for serous histology where it was 2:1. Rate of distant relapses in LVSI-negative, LVSI-positive and node-positive patients was 7%, 14% and 26%, respectively. Three distinct prognostic cluster emerged with 5-year OS of 91.0%, 82.9% and 69.9%. Conclusion LVSI was the most important prognostic factor in endometrial cancer. Using LVSI and lymph-node status, it was possible to stratify endometrial cancer patients in three distinct prognostic clusters of low, intermediate and high risk of relapse. Such stratification could assist in patient selection for evaluating novel adjuvant therapy protocols.