To investigate the correlation between surgical complexity score (SCS), disease score (DS), and residual disease (RD) in patients with advanced epithelial ovarian cancer (EOC) undergoing interval debulking surgery (IDS), with the aim of informing individualized surgical decision-making.

A total of 160 patients with advanced EOC who underwent neoadjuvant chemotherapy (NACT) followed by IDS at West China Second University Hospital, Sichuan University, between September 2013 and June 2018 were retrospectively analyzed. According to whether complete cytoreduction (R0) was achieved, patients were categorized into the R0 group (n=86) and the RD group (n=74). Clinical data, including baseline characteristics, histopathological findings, laboratory results, postoperative complications, and prognosis, were collected for both groups. Statistical analyses were performed using the Mann-Whitney U test, Pearson′s chi-square test, or Fisher′s exact test, as appropriate, to compare clinical variables between the two groups. Multivariate unconditional logistic regression analysis was conducted to identify independent factors associated with achieving R0 resection in advanced EOC patients. The Mantel-Haenszel chi-square test was used to evaluate the correlation between SCS and DS. Kaplan-Meier survival analysis with the Log-rank test was employed to compare overall survival (OS) between the R0 and RD groups. This study was approved by the Ethics Committee of West China Second University Hospital, Sichuan University, and conducted in accordance with its ethical requirements (Approval No. 2022-167).

① The preoperative carbohydrate antigen 125 (CA125) level in the RD group was significantly higher than that in the R0 group (Z=-2.52, P=0.012). ② The distribution of DS grades between the two groups differed significantly was (χ²=10.92, P=0.004), the distribution of SCS between the two groups also differed significantly (χ²=15.41, P=0.001). DS was an independent risk factor for reaching R0 after receiving IDS, while SCS was an independent protective factor. Multivariate unconditional logistic regression analysis indicated that patients with moderate DS had a significantly lower likelihood of achieving R0 resection compared with those with low DS (OR=0.094, 95%CI: 0.021-0.431, P=0.002), whereas patients with moderate SCS were more likely to achieve R0 compared with those with low SCS (OR=13.660, 95%CI: 2.150-86.803, P=0.006). ③ Mantel-Haenszel χ² test revealed no significant trend correlation between DS and SCS in patients with advanced EOC (χ²=0.01, P=0.906). ④ The Log-rank test demonstrated that the survival curves of the two groups differed significantly (χ²=9.46, P=0.002). ⑤ Comparisons of age, American Society of Anesthesiologists (ASA) classification, DS grade, and SCS grade between patients with and without postoperative complications showed no significant differences (all P>0.05).

For patients with advanced EOC treated with NACT followed by IDS, increasing surgical complexity may facilitate the achievement of R0 resection and improve prognosis. However, such an approach requires careful consideration of tumor burden and the risk of postoperative complications. Preoperative comprehensive evaluation and individualized decision-making are therefore recommended.