Novel preoperative predictive score to evaluate lymphovascular space involvement in endometrial cancer: an aid to the sentinel lymph node algorithm.

Introduction: Sentinel lymph node (SLN) dissection has been recognized as a valid tool for staging in patients with endometrial cancer. Several factors are predictors of recurrence and survival in endometrial cancer, including positive lymphovascular space invasion. The aim of this study is to formulate a pre-operative score that, in the event of no-SLN identification, may give an estimate of the true probability of lymphovascular space invasion and guide management.

Methodology: This was a multi-institutional retrospective study conducted from January 2007 to December 2017. We included all patients with any grade endometrial tumor with a complete pathological description of the surgical specimen and with a minimum follow-up of 12 months. All patients underwent a class A hysterectomy according to Querleu and Morrow and bilateral salpingo-oophorectomy. Lymphadenectomy was performed based on patient risk of node metastases. In order to verify the predictive capacity of the parameters associated with lymphovascular space invasion status, grading, abnormal CA125 (>35 units/ml), myometrial invasion, and tumor size, a synthetic score was calculated. The score was introduced in the receiver operating characteristic curve model in which the binary classifier was represented by the lymphovascular space invasion status. The ideal cut-off was calculated with the determination of the Youden index. Sensitivity and negative predictive value of lymphovascular space invasion score was calculated in patients with lymph node metastasis.

Results: Six hundred and fourteen patients were included in the study. The average age and BMI of patients were 64.8 (range 33-88) years and 30.1 (range 17-64) respectively. Of the 284 patients who underwent lymphadenectomy, 231 (81.3%) patients had no lymph node metastases, 33 (11.6%) patients had metastatic pelvic lymph nodes, 12 (4.2%) patients had metastatic aortic lymph nodes, and eight (2.8%) patients had both pelvic and aortic metastatic lymph nodes. Lymphovascular space invasion was associated with deep myometrial infiltration (P<0.001), G3 grading (P<0.001), tumor size ≥25 mm (P=0.012), abnormal CA125 (P<0.001), recurrence (P<0.001), overall survival (P<0.001), and disease-free survival (P<0.01). Of all patients with lymphovascular space invasion, 79% had an lymphovascular space invasion score ≥5. The score ranged from a minimum score of 1 to a maximum of 7. The score shows 78.9% sensitivity (95% CI 0.6971 to 0.8594), 65.3% specificity (95% CI 0.611 to 0.693), 29.4% positive predictive value (95% CI 0.241 to 0.353), and 94.4% negative predictive value (95% CI 0.916 to 0.964).

Conclusion: We found that when lymphovascular space invasion score ≤4, there is a very low possibility of finding lymph nodal involvement. The preoperative lymphovascular space invasion score could complement the SLN algorithm to avoid unnecessary lymphadenectomies.