BACKGROUND: The chemotherapy response score (CRS) evaluates the response to neoadjuvant chemotherapy (NACT) in high-grade serous ovarian cancer (HGSOC). This study aimed to develop a prognostic nomogram combining CRS and clinical characteristics to improve outcome predictions for NACT-treated patients. METHODS: We retrospectively analyzed 271 HGSOC patients who received NACT. Univariate and multivariate regression analyses were conducted to identify independent prognostic factors, which were then used to construct a nomogram. The nomogram's performance was evaluated using the concordance index (C-index), calibration plots, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA). RESULTS: Patients were randomly divided into the training cohort (n=181) and validation cohort (n=90). Cox regression analysis identified debulking status, CRS, and post-adjuvant chemotherapy cancer antigen 125 (PACT-CA125) levels as independent prognostic factors, which were incorporated into the nomogram. The nomogram demonstrated C-indices of 0.735 and 0.730 in the training and validation cohorts, respectively. The ROC curves, calibration plots, and DCA confirmed the nomogram's strong predictive performance. Notably, longer progression-free survival was observed in patients with <
3 cycles of adjuvant chemotherapy in low-risk groups, while similar findings were not obtained in the high-risk group. CONCLUSIONS: This study developed a novel prognostic nomogram incorporating debulking status, CRS and PACT-CA125 levels for NACT-treated HGSOC patients. It serves as a valuable tool for personalized treatment planning and survival assessment, assisting clinicians in making individualized decisions.