Objective The aim was to study the association of L1 cell adhesion molecule (L1CAM) expression with the outcome of patients with endometrial cancer, especially with regard to conventional risk variables, and to compare the patterns of relapse in L1CAM-positive and -negative cancers.

Methods This was a retrospective study of 805 women. The Kaplan–Meier method and univariate and multivariate Cox regression models were applied for survival analyses. Missing data were replaced using multiple imputation. The median follow-up time was 51 months (range, 1–98).

Results One hundred twenty-one (15.0%) cases were L1CAM positive. L1CAM positivity was associated with high stage (I vs II–IV) (odds ratio [OR], 2.3), lymph node involvement (OR, 2.9), poor differentiation (OR, 6.1), non-endometrioid histology (OR, 9.9), lymphovascular space invasion (OR, 2.8), cervical stromal invasion (OR, 1.8), positive peritoneal cytology (OR, 4.1), and age older than 65 years (OR, 2.8). The frequencies of deep myometrial invasion (50% or deeper), tumor size 2 cm or greater, and body mass index 30 kg/m² or greater were not significantly different between L1CAM-positive and -negative cases. L1CAM predicted poor disease-specific survival in endometrioid (P < 0.0001) but not in non-endometrioid carcinomas (P = 0.934). The negative impact of L1CAM on outcome was confirmed in a Cox multivariate disease-specific survival analysis. Univariate survival analyses in the different ESMO–ESGO–ESTRO endometrial cancer risk groups showed an association between L1CAM positivity and poor outcome in intermediate (hazard ratio, 12) and high-risk advanced metastatic (hazard ratio, 2.0) groups. Extra-abdominal relapses were more frequent in L1CAM-positive (13.2%) than L1CAM-negative (1.9%) stage I endometrioid carcinomas (P < 0.0001), whereas other site-specific relapses in local cancers were L1CAM independent.

Conclusions L1CAM is associated with the occurrence of poor prognostic variables and predicts advanced disease in endometrial cancer. L1CAM predicts extra-abdominal relapses and poor survival in endometrioid endometrial cancer, but seems not to be a prognostic factor in non-endometrioid carcinomas.