The significance of lower uterine segment involvement in endometrial cancer.

Background: Limited data suggests lower uterine segment involvement (LUSI) in endometrial cancer may be associated with other poor prognostic factors. We assessed the unclear impact of LUSI on prognosis in endometrial cancer.

Method: ology: A revision of pathological samples following surgical staging between the years 2002-2022 was performed and clinical data collected from patients' records. Characteristics and outcomes of women with and without LUSI were compared and analysed. Kaplan Meyer survival curves compared overall survival (OS) and progression-free survival (PFS).

Results: 429 women were included, of which 45 (10.5%) had LUSI. No differences were found between the groups regarding demographic or clinical characteristics. LUSI was significantly associated with lympho-vascular space invasion (40% vs. 22% p = 0.01), lymph node involvement (6.4% vs. 9.1%, p = 0.05), shorter PFS (4 vs. 5.5 years, p = 0.01) and OS (5.6 vs. 11.5 years, p = 0.03). Multivariate analysis showed higher hazard ratios for OS and PFS (1.55 95%CI 0.79-3.04 and 1.29 95%CI 0.66-2.53, respectively) but these were insignificant even in a sub-analysis of endometrioid histology (1.76 95%CI 0.89-3.46 and 1.35 95%CI 0.69-2.65, respectively). A trend towards decreased PFS and OS was demonstrated in the Kaplan Meyer survival curves for all cases (log rank test p = 0.5 and 0.29 respectively), endometrioid histology (log rank test p = 0.06 and 0.51 respectively) and early-stage disease (log rank test p = 0.63 and 0.3 respectively).

Conclusion: LUSI may be related to poorer outcome of endometrial cancer and may represent an additional factor to consider when contemplating adjuvant treatment, especially in endometrioid-type and early-stage disease.