Pathologic Primary Tumor Factors Associated With Risk of Lymph Node Involvement in Patients With High-Risk Endometrial Cancer

Abstract

National Comprehensive Cancer Network guidelines recommend adjuvant systemic therapy with or without external beam radiation and/or intravaginal brachytherapy for high-risk endometrial cancer histologies. Being able to estimate the risk of pelvic/para-aortic lymph node (LN) involvement could assist in making clinical decisions regarding whether to treat with external beam versus brachytherapy alone. The National Cancer Data Base was queried to develop predictive nomograms based on primary uterine factors to estimate the risk of pathologic LN involvement.Patients diagnosed with pathologic T1-T2 clear cell, uterine papillary serous (UPS), carcinosarcoma, or mixed endometrial cancer between 2004-2016 undergoing primary surgery with at least 10 LNs sampled in the National Cancer Data Base were identified. Logistic regression was performed to identify primary pathologic tumor predictors of LN positivity. Pathologic variables assessed included primary tumor histology, pathologic tumor stage, tumor size, and presence/absence of lymphovascular invasion (LVI). Nomograms were created to predict overall, pelvic only, and paraaortic and/or pelvic LN involvement.Among 7,918 patients included, 1,407 (18%) were node positive. On multivariable analysis, relative to carcinosarcoma, both clear cell (odds ratio [OR] 1.77, 95% confidence interval [CI] 1.34-2.32, P < 0.001) and UPS (OR 1.76, 95% CI 1.46-2.13, P < 0.001) histology were significantly associated with a higher risk of LN positivity while mixed histology was not (OR 1.14, 95% CI 0.95-1.37, P = 0.16). Furthermore, increasing pathologic tumor stage (pT2 versus pT1a, OR 3.62, 95% CI 3.04-4.28, P < 0.001), increase in tumor size per centimeter (OR 1.09, 95% CI 1.06-1.11, P < 0.001), and presence of LVI (OR 5.23, 95% CI 4.58-6.02, P < 0.001) were predictive of overall LN positivity. Nomograms demonstrated that the impact of primary tumor pathologic variables was comparable for predicting any LN involvement, pelvic only, and paraaortic with or without pelvic LN involvement.Among endometrial cancer patients with high-risk histologies, predictors of LN positivity are similar to those with endometrial adenocarcinoma. Patients with carcinosarcoma are the least likely to be diagnosed with node positive disease relative to other high-risk histologies. Predictive nomograms can help to individualize the risk of pelvic and paraaortic LN involvement and may assist in adjuvant treatment decisions.E. Anderson: None. M. Luu: None. D.J. Lu: None. E.M. Chung: None. M. Kamrava: American Board of Radiology, Brachytherapy Journal, American Brachytherapy Society Board of Directors. Co-Editor; Journal of Contemporary Brachytherapy.