Clinical impact of CA-125 ELIMination rate constant K (KELIM) on surgical strategy in advanced serous ovarian cancer patients

Objectives The modeled CA-125 elimination constant K (KELIM) is a pragmatic early marker of tumor chemosensitivity in ovarian cancer patients treated with neoadjuvant chemotherapy before interval surgery. The primary objective of this study was to assess the prognostic value of KELIM regarding the feasibility of complete surgery, and secondary objectives were to assess the prognostic value of KELIM for the risk of a platinum resistant relapse, progression free survival, and overall survival. Methods The study was based on a retrospective cohort of 284 patients treated for an advanced serous high grade ovarian cancer, International Federation of Gynecology and Obstetrics (FIGO) stages III-IV, with neoadjuvant chemotherapy, followed by interval surgery, in a comprehensive cancer center. CA-125 concentrations at baseline and during neoadjuvant chemotherapy were collected. The KELIM predictive value regarding the tumor radiological response rate, likelihood of complete surgery, risk of subsequent platinum resistant relapse, progression free survival, and overall survival were assessed with univariate and multivariate tests. Results In 232 patients, KELIM was an independent and major predictor of the probability of complete surgery and survival. The final logistic regression model, including KELIM (odds ratio (OR) 0.36, 95% confidence interval (CI)0.16 to 0.73, p=0.006) and complete surgery (no vs yes, OR 0.29, 95% CI 0.15 to 0.53, p<0.001), highlighted the complementary impact of chemosensitivity and surgical outcome relative to the complete surgery. In the multivariate analysis, KELIM and complete surgery were significantly associated with a lower risk of early relapse. In the case of an unfavorable KELIM, when surgical efforts allowed complete cytoreduction, median overall survival was similar to that reported in the case of a favorable KELIM (46.3 months (range 34.6-60.3) vs 46.5 months (range 40.6-68.7), respectively). Conclusion Primary tumor chemosensitivity, assessed by the modeled CA-125 KELIM, calculated during neoadjuvant chemotherapy, is a major parameter to consider for decision making regarding interval surgery. Complementary to the RECIST score and laparoscopy, this non-invasive tool, available online, helps tailor the interval surgery strategy according to patient tumor chemosensitivity.