RESUMO
PURPOSE/OBJECTIVES: Lymph node (LN) involvement is an important factor in guiding adjuvant treatment for patients with endometrial cancer. Risk factors for LN involvement are fairly well-established for endometrial adenocarcinoma, but it is not as well defined whether these factors similarly predict LN positivity in less common histologies. MATERIALS/METHODS: Patients diagnosed with pathologic T1-T2 carcinosarcoma, clear cell, uterine papillary serous carcinoma (UPSC), and mixed histologic type endometrial cancer between 2004 and 2016 undergoing primary surgery with at least 1 lymph node sampled in the National Cancer Data Base were identified. Logistic regression was performed to identify primary pathologic tumor predictors of LN positivity. Nomograms were created to predict overall, pelvic only, and paraaortic with or without pelvic LN involvement. RESULTS: Among 11,390 patients included, 1950 (18%) were node positive. On multivariable analysis, increasing pathologic tumor stage (pT2 versus pT1a, odds ratio [OR] 3.63, 95% confidence interval [CI] 3.15-4.18, p < 0.001), increase in tumor size per centimeter (OR 1.08, 95% CI 1.06-1.10, p < 0.001), and the presence of lymphovascular invasion (LVI) (OR 4.97, 95% CI 4.43-5.57, p < 0.001) were predictive of overall LN positivity. Relative to carcinosarcoma, both clear cell (OR 1.54, 95% CI 1.22-1.95, p < 0.001) and UPSC (OR 1.73, 95% CI 1.48-2.02, p < 0.001) histology were significantly associated with a higher risk of LN positivity while mixed histology was not (OR 1.07, 95% CI 0.92-1.24, p = 0.42). CONCLUSION: Among patients with non-endometrioid endometrial cancer, predictors of LN positivity are similar to endometrial adenocarcinoma. The nomograms provided could be helpful in making adjuvant treatment decisions for these less common histologies.