Concordance between preoperative ESMO-ESGO-ESTRO risk classification and final histology in early-stage endometrial cancer

Objective: To evaluate the concordance between preoperative European Society for Medical Oncology (ESMO)-European Society of Gynaecological Oncology (ESGO)-European SocieTy for Radiotherapy and Oncology (ESTRO) risk classification in early-stage endometrial cancer (EC) assessed by biopsy and magnetic resonance imaging (MRI) with this classification based on histology of surgical specimen. Methods: This bicentric retrospective study included women diagnosed with early-stage EC (<= stage II) who had a complete preoperative assessment and underwent a surgical management from January 2011 to December 2018. Patients were preoperatively classified into 3 degrees of risk of lymph node (LN) involvement based on biopsy and MRI. Based on final histological report, patients were re-classified using the preoperative classification. Concordance between the preoperative assessment and definitive histology was calculated with weighted Cohen's kappa coefficient. Results: A total of 333 women were included and kappa coefficient of preoperative risk classification was 0.49. The risk was underestimated and overestimated in 37% and 10% of cases, respectively. Twenty-nine percent of patients had an incomplete LN staging according to the degree of risk of re-classification. The observed discordance in the risk classification was attributed to MRI in 75% of cases, to biopsy in 18% and in 7% to both (p<0.001). Kappa coefficient for concordance was 0.25 for MRI and 0.73 for biopsy. Conclusion: Concordance between preoperative ESMO-ESGO-ESTRO risk classification and final histology is weak. Given that the risk was underestimated in the majority of patients wrongly classified, sentinel LN procedure instead of no LN dissection could be an option offered to preoperative low-risk patients to decrease the indication of second surgery for restaging and/or to avoid toxicity of adjuvant radiotherapy.