Introduction/Background Endometrial cancer (EC) is the most common gynaecologic malignancy in developed countries. Molecular classification of EC includes 4 subtypes: POLE-ultramutated (POLEmut), mismatch-repair protein deficient (MMRd), p53-mutant (p53abn) and no specific molecular profile (NSMP). Lymphovascular space invasion (LVSI) appears as an independent risk factor for nodal metastases. Herein, we evaluate the impact of LVSI on nodal metastases (N+) and its association with molecular classification.

Methodology We conducted a monocentric retrospective study of 171 consecutive patients treated for EC at the University Hospital of Liège between January 2019 and October 2022. LVSI data were reported for 155 patients from whom 107 had surgical nodal staging and LVSI quantification, 64 patients were thus excluded. Full IHC and molecular biology analyses were available for 89 patients (83.18%). LVSI was classified as absent (LVSI-) or present (LVSI+). LVSI+ included less than five vessels involved (LVSI<5) and equal or more than five vessels involved (substantial LVSI, LVSIsubst).

Results 32 patients (35.95%) were LVSI- and none were N+, their molecular profiles were as follows: 6 MMRd (18.75%), 7 p53abn (21.88%), 2 POLEmut (6.25%) and 17 NSMP (53.12%). Thirty-seven patients (41.57) were LVSI<5 of which 2 were N+ (5.4%), the molecular profiles were as follows: 14 MMRd (37.84%), 8 p53abn (21.62%), 3 POLEmut (8.11%) and 12 NSMP (32.43%). 20 patients (22.47%) were LVSIsubst of whom 5 were N+ (25%), their molecular profiles were: 12 MMRd (60%), 5 p53abn (25%), no POLEmut and 3 NSMP (15%).

Conclusion In our study, no LVSI- patient presented nodal metastases despite 40% of them being p53abn or MMRd. On the other hand, 25% of LVSIsubst patients were N+ and 85% of them were MMRd or p53abn. LVSI status seems to have a greater impact on nodal metastases risk than molecular classification.

Disclosures There are no disclosures to declare.