Analysis of metastatic regional lymph node locations and predictors of paraaortic lymph node involvement in patients with endometrial cancer

Objective: To provide detailed knowledge of the metastatic lymph node (LN) locations and to determine factors predicting paraaortic LN metastasis in endometrial cancer patients at–risk for LN involvement. Methods: A prospective case–series with planned data collection was conducted in a total of 173 patients who treated with systematic pelvic–paraaortic lymphadenectomy up to the renal vessels. All the LNs removed from pelvic and paraaortic basins – "low or high" according the level of inferior mesenteric artery (IMA) – were evaluated separately. Logistic regression analyses were performed to determine the impact of variables on paraaortic metastasis. Results: LN metastasis was observed in 21.9% of the patients, pelvic LN involvement in 17.9%, paraaortic LN involvement in 15.0%, both pelvic and paraaortic LN involvement in 10.9%, and isolated paraaortic LN involvement in 4.0%. The most common metastatic LN locations were the external iliac (50.0%), obturator (50.0%), and low–precaval regions (36.8%). The least common location of metastasis was the high–precaval region (5.3%). Among patients with paraaortic LN metastasis, 42.3% had metastasis above IMA. The number of metastatic pelvic LNs ≥2 was the only independent predictor of paraaortic metastasis in multivariate analysis with 96.94% sensitivity, 95.87% specificity, 98.6% positive predictive value, and 97.0% negative predictive value (NPV). Conclusion: The present study provides evidence that the number of metastatic pelvic LNs ≥2 is the sole predictor of paraaortic LN metastasis with a high sensitivity and NPV. In high-risk patients pelvic-para-aortic lymph node dissection up to the renal vessels required. It needs to be investigated in sentinel node studies to allow better selection of patients for paraaortic lymphadenectomy