External validation of standardized KELIM and platinum resistant recurrence score in patients with advanced epithelial ovarian cancer

Background Neoadjuvant chemotherapy followed by interval debulking surgery is today a valid treatment option for advanced epithelial ovarian cancer (EOC). This schema allows in vivo evaluation of the chemosensitivity of the tumor, however there is still no clearly validated marker. The Standardized CA-125 ELIMination rate constant K (Std KELIM) and the Platinum Resistant Recurrence (PtRR) Score have been proposed as markers. The aim of our study was to validate these two tools for predicting platinum sensitivity in a real-world population with advanced EOC. Experimental design: All patients with advanced EOC treated with neoadjuvant chemotherapy followed by interval debulking surgery in Institut Curie between 2000 and 2015 were included. Std KELIM was calculated with the CA-125 concentrations at each cycle. The predictive value of Std KELIM and the validation of the PtRR Score regarding the risk of subsequent platinum-resistant relapse were assessed using ROC curve, logistic regression and calibration curve. Results Std KELIM was calculated for 152 patients. The AUC was 0.67 with an optimal threshold at 0.61. A low Std KELIM was significantly associated with PtRR (odds-ratio = 0.19 (95% CI [0.06, 0.53], p = 0.002) in the univariate analysis but not in the multivariate analysis after adjustment on complete IDS status, which was the only independent predictive factor. The calibration curve of PtRR score presents a slight but significant underestimation (p = 0.02) of the risk of platinum-resistant relapse. Conclusions Std KELIM and PtRR score are early predictive markers of platinum resistance. They could be used in a clinical trial for assisting the clinician in adapting medical treatment.