Session Item

Lymphovascular space invasion (LVSI) predicts for higher rates of recurrence and increased mortality in endometrial cancer. Using three-tier LVSI scoring, a pooled analysis of the PORTEC 1&2 trials demonstrated that substantial LVSI was associated with worse locoregional- and distant disease-free survival, and these patients possibly benefited from EBRT. In patients with lymph node (LN) evaluation, substantial LVSI is a predictor for LN involvement. However, it is unknown if the significance of substantial LVSI remains in patients with a pathological negative LN assessment.  We therefore aimed to evaluate clinical outcomes of patients with pathological negative LN assessment in relation to three-tier LVSI scoring system. 

We performed a single-institutional retrospective review of patients with Stage I endometrioid-type endometrial cancer who underwent surgical staging with pathological negative LN evaluation from July 2017 - September 2019. Three-tier LVSI scoring (none, focal, or substantial) was performed by gynecologic pathologists. Patients with ITCs were included. Patients with non-endometrioid type, mixed histology tumors, or synchronous cancers were excluded. Clinical outcomes (loco-regional disease-free survival [LR-DFS], distant metastasis disease-free survival [DM-DFS], overall survival [OS]) were analyzed using Kaplan-Meier method. 

After surgical staging, 335 patients with pathological LN negative Stage 1 endometrioid-type endometrial carcinoma were identified. Median patient age was 63.9 years. Substantial LVSI was present in 59 patients (17.6%). Majority of patients (50.5%) were observed after surgery, 39.7% received adjuvant vaginal brachytherapy, and 6.9% received both EBRT and vaginal brachytherapy. Adjuvant radiation treatment varied with the three-tiered LSVI scoring system (p<0.01). In patients with no LVSI, the majority of patients were observed (75.1%). In patients with focal LVSI, 81.0% of patients received vaginal brachytherapy. Among patients with substantial LVSI, 57.9% received vaginal brachytherapy, and 31.6% of patients received both vaginal brachytherapy and EBRT. The majority of patients (95.8%) received no chemotherapy. With a median follow-up of 25.7 months, the 2-year LR-DFS rates were 92.5%, 98.0%, and 92.7% for no LVSI, focal LVSI, and substantial LVSI, respectively. For DM-DFS, 2-year rates were 95.5%, 93.3%, and 93.8% for no LVSI, focal LVSI, and substantial LVSI, respectively. The 2-year rates for OS were 97.6%, 98.1%, and 98.2% for no LVSI, focal LVSI, and substantial LVSI, respectively.

In our single institution study, patients with pathological LN negative stage I endometrioid-type endometrial cancer with substantial LVSI have similar rates of LR-DFS, DM-DFS, and OS compared to patients with none/focal LVSI. Compared to the PORTEC findings, these findings suggest the need for additional multi-institutional studies to confirm the prognostic value of substantial LVSI in this patient cohort.