Lymphovascular Invasion in Endometrial Cancer: Prognostic Value and Implications on Adjuvant Radiation Therapy Use

Objectives: Lymphovascular space invasion (LVSI) is a known prognostic factor for endometrial carcinomas. However, LVSI as a determinant of treatment benefit has not been fully elucidated. Methods and Materials: Data from the National Cancer Database for endometrial cancer from 2004 to 2012 was obtained. Univariate and multivariate analysis was performed to assess the impact of LVSI on overall survival (OS). Survival analysis was performed utilizing logrank and Kaplan-Meier analyses. The difference in OS between external beam radiation therapy (EBRT) and vaginal brachytherapy (VBT) in LVSI-positive patients was analyzed with propensity score matching. Results: A total of 32,150 patients with surgical stage I to III endometrial carcinomas were available for analysis with a median follow-up of 30 months. Twenty-nine percent were LVSI positive and received adjuvant radiotherapy (aRT) more often than if LVSI negative (57% vs. 37%). On multivariate analysis, LVSI (hazard ratio, 1.94; P<0.01) was associated with an increased risk of death. aRT improved OS for LVSInegative patients (87% without aRT, 90% with aRT; P=0.006). aRT was particularly effective in LVSI-positive patients: all stages of LVSIpositive patients were associated with an OS benefit (P<0.01), whereas among LVSI-negative patients, only stage III benefited from aRT (P<0.01). After propensity score match, there was no OS difference between EBRT and VBT among LVSI-positive patients (hazard ratio, 1.15; P= 0.44). Conclusions: LVSI is an independent prognostic factor in locoregional endometrial carcinomas. aRT benefited all stages of LVSI-positive patients, but only stage III of LVSI-negative patients. Among LVSIpositive patients, we did not find an OS difference between adjuvant EBRT versus VBT.