Pathologic primary tumor factors associated with risk of pelvic and paraaortic lymph node involvement in patients with endometrial adenocarcinoma

The presence of lymph node (LN) positivity in endometrial adenocarcinoma (EAC) patients guides adjuvant treatment, but recommendations regarding LN evaluation at the time of primary surgery remain variable. Primary pathologic tumor characteristics may predict risk of LN involvement in EAC patients with limited LN evaluation. Patients diagnosed between 2004–2016 with pathologic T1–T2 EAC in the National Cancer Database who had at least one lymph node sampled at the time of surgery were included. Pathologic primary tumor predictors of LN involvement were identified using logistic regression. To predict overall, pelvic only, and paraaortic and/or pelvic LN involvement, nomograms were generated. Among 57,810 EAC patients included, 4002 were node positive. On multivariable analysis, increasing pathologic tumor category (pT2 versus pT1a, odds ratio (OR) 5.43, 95% confidence interval (CI) 4.89–6.02, p < 0.001), increasing pathologic tumor grade (grade 3 versus grade 1, OR 1.62, 95% CI 1.47–1.79, p < 0.001), increase in tumor size per centimeter (OR 1.05, 95% CI 1.04–1.06, p < 0.001), and presence of lymphovascular invasion (LVI) (OR 6.33, 95% CI 5.87–6.83, p < 0.001) were predictive of overall LN positivity. The presence of LVI was a stronger predictor of paraaortic LN involvement (OR 6.43, 95% CI 5.55–7.47, p < 0.001) than pelvic LN involvement (OR 5.42, 95% CI 4.98–5.90, p < 0.001) in multivariable analysis. For patients with limited LN evaluation, pathologic tumor features can be used to estimate the risk of pelvic or paraaortic LN involvement. This information may inform adjuvant treatment decisions and guide future studies.