The prognostic and decision-making impact of KELIM CA-125 in patients with advanced ovarian cancer: A real-world study from Bosnia and Herzegovina.

BACKGROUND Developing countries face limited access to targeted treatments for patients with advanced epithelial ovarian cancer (EOC). The CA-125 ELIMination rate constant K (KELIM), calculated from longitudinal CA-125 measurements during the first 100 days of treatment, serves as an early indicator of tumour chemosensitivity. The primary objective of this study was to evaluate the value of the KELIM score in predicting progression-free survival (PFS) and overall survival (OS) in patients with EOC treated with adjuvant or neoadjuvant chemotherapy. METHODS The records of patients with EOC (International Federation of Gynecology and Obstetrics stage II-IV) treated at the University Clinical Hospital Mostar (Bosnia and Herzegovina) between 2013 and 2023 were analysed retrospectively. Patient characteristics, outcomes and KELIM score were assessed during the first 100 days of treatment. KELIM scores were categorized as favourable (≥1.0) or unfavourable (<1.0). RESULTS KELIM scores were assessed in 92 patients: 36 (39 %) were classified in the favourable group and 56 (61 %) in the unfavourable group. Patients in the favourable KELIM group achieved complete cytoreduction significantly more often (p < 0.001) and demonstrated longer platinum-free intervals (PFI), with most having PFI > 12 months (p = 0.005). In contrast to OS (p = 0.442), PFS was significantly longer in the favourable KELIM group [29.0 months, 95 % confidence interval (CI) 8.45-49.55] compared with the unfavourable KELIM group (13.0 months, 95 % CI 10.56-15.44; p < 0.001). CONCLUSION In this real-world cohort from a resource-limited setting, a favourable KELIM score was associated with greater early chemosensitivity, longer PFI, improved PFS, and a higher rate of complete cytoreduction in patients with EOC. The KELIM score has been validated in real-world settings and post-hoc analyses of prospective studies, and can be applied easily in routine clinical practice for patients with EOC treated with adjuvant or neoadjuvant chemotherapy, providing a useful prognostic, predictive, pragmatic and cost-effective tool to support risk stratification and inform therapeutic decision-making. Further prospective validation is still required for biomarker-guided treatment selection.