Introduction/Background Myometrial invasion (MI) and tumor free distance (TFD) from serosa are associated with an increased risk of relapse in patients with endometrioid endometrial carcinoma (EEC). The extent of the MI has been recognized as an essential prognostic risk factor; instead the TFD doesn’t have the same prognostic role, but may be associated with a higher risk of recurrence.

The aim of our study was to investigate the role of the percentage of MI related to TFD as prognostic risk factor.

Methodology In our retrospective study we enrolled all FIGO Stage IB EEC with at least one year follow up treated in our institution. All patients were stratified in three different subgroups based on tumor invasion in the myometrial layer and TFD, calculating the actual percentage of involved myometrial thickness (Group1: 50–69,9%, Group 2: 70–89,9% and Group 3: 90–100%).

We correlated the subgroups with several variables as sentinel lymph node (SLN) status, tumor grading, lymphovascular space invasion (LVSI), and local/distant recurrence.

Results Twenty-one patients met the inclusion criteria. Four patients were included in the group 1 and one (25%) of them had positive SLN for micrometastasis. In the second group we found 11 patients: 5 (45%) of them had positive SLN and 1 showed local relapse (9%). Moreover one patient had concomitant breast cancer (9%). The group 3 included 6 patients: 2 (33%) were positive for SLN and 1 (16%) of them also had distant relapse.

Conclusion Percentage of MI related to TFD represents a promising prognostic risk factor that seems to be associated with an increased risk of relapse such as SLN positivity, especially in those patients with more than 70% of myometrial invasion. Further studies with larger sample size are required to evaluate the relation between MI and TFD as prognostic risk factor in EEC.

Disclosures None.