Tumor Diameter-Based Triage for Systematic Lymphadenectomy in Low Grade, Superficial Myoinvasive Endometrioid Endometrial Cancer: A Retrospective Diagnostic Accuracy Study

Purpose In this study, we aimed to assess the efficacy of different tumor diameter cutoffs in diagnosing lymphatic metastasis in low-grade endometrioid endometrial cancer patients with superficial myometrial invasion. Methods Clinical early-stage endometrioid endometrial cancer patients with myometrial invasion < 50% who underwent comprehensive staging, including at least pelvic lymphadenectomy, were retrospectively analyzed. Diagnostic accuracy for detecting lymphatic metastasis and unnecessary lymphadenectomy procedure rates were calculated separately for tumor diameter > 20 mm and tumor diameter > 30 mm. Results Two hundred and three patients fulfilled the study criteria exactly. Seven (3.44%) patients were diagnosed with lymphatic metastasis. If tumor diameter ≥ 20 mm was taken as a cutoff for the systematic lymphadenectomy, 128 (63%) patients had this procedure, and we would diagnose all lymphatic metastases. If the tumor diameter cutoff value were determined as 30 mm, the systematic lymphadenectomy rate would be 31.5% ( n = 64). However, three of the seven lymphatic metastases would be missed. Sensitivity, specificity, positive predictive value, negative predictive value, and false-negative rates were 100%, 38.27%, 5.47%, 100%, and 0%, respectively, for the Mayo Algorithm (20 mm cutoff value) and 57.14%, 69.39%, 6.25% and 97.84% and 42.86%, respectively, for the 30 mm cutoff value for the diagnosis of lymphatic metastasis. Conclusion Two-thirds of the low-grade, superficial myoinvasive endometrial cancer patients were included in a high-risk group for lymphatic metastasis after using 20 mm tumor diameter as a cutoff value. Many cases still undergo unnecessary systematic lymphadenectomy. On the other hand, increasing tumor diameter cutoff from 20 to 30 mm will decrease the lymphadenectomy rate by 50%, but a high false-negative rate makes this approach useless.