Introduction The optimal timing of interval debulking surgery (IDS) after neoadjuvant chemotherapy (NACT) in advanced epithelial ovarian cancer (EOC) is uncertain. Hence, there is a need to have a reliable test that can predict the feasibility of CC0.

Methods Patients with stage III/IV EOC, fallopian tube, or primary peritoneal cancer treated in 2016–2021 were identified from a single institution. Their clinical parameters and surgical records reviewed retrospectively.

Results 260 eligible patients were identified. 125 patients (54.3%) received NACT, among which 2 (1.6%) had non-evaluable CA125 (i.e., baseline is <2x upper normal limit), and 14 (11.2%) could not undergo IDS due to disease burden. Finally, 100 patients with documentation on the CC0 were included in the analysis (table 1). CC0 rate was 67%. Univariate analysis showed that the presence of ascites, diaphragmatic and mesenteric masses, median change of CA125 level, median Fagotti’s score based on pre-operative imaging, were significantly associated with CC0. Multivariate analysis showed that the change of CA125 level was not significant (p=0.069, odds ratio (OR) 0.968; 95% confidence interval (CI) 0.934–1.003), and the only significant parameter was pre-operative radiological Fagotti’s score (p=0.008; OR 1.521; 95% CI 1.117–2.071). Receiver operating characteristics (ROC) curve analysis showed that the area under the curve (AUC) of CA125 in predicting CC0 was 0.678 and 0.740 respectively (figure 1), and the estimated sensitivity of CA125 was 0.53 only.

Conclusion/Implications The result highlighted the insufficiency of CA125 in predicting CC0. More simple and novel markers are needed to predict the feasibility of CC0.