Correlating the KELIM (CA125 elimination rate constant K) score and the chemo-response score as predictors of chemosensitivity in patients with advanced ovarian carcinoma

Background The objective of this study is to assess the correlation between the pre-operative CA125 Elimination rate constant K(KELIM) score and the intraoperative chemo-response score (CRS) in patients with advanced high grade serous ovarian cancer(HGSC) treated with neoadjuvant chemotherapy(NACT). Methods This is a retrospective cohort study of patients with Stage III-IV HGSC treated with NACT from March 2010 to December 2019 at Princess Margaret Cancer Center, Toronto, Canada. KELIM scores were calculated based on the tool devised by You et al. available online. CRS was assessed using an established 3-tier scoring system. An association analysis was performed to determine if the KELIM score assessed during NACT can predict CRS score at the time of interval cytoreductive surgery(ICS). Results 172 patients were included in this analysis. Patients with CRS 1–2 had a lower median Platinum Free Interval(PFI) (9.24 vs 13.64 months, p = 0.005), lower median progression free survival(PFS) (14.99 vs 20.29 months, p = 0.003) and lower 5-year overall survival(OS) (63.8% vs 69.7%, p = 0.54) compared to patients with CRS3. Among patients with CRS 1–2(n = 115), 68.7% had KELIM <1, while 56.2% of patients with CRS3 had KELIM ≥1(56.2%), p = 0.0017, suggesting a correlation between the KELIM and CRS scores. Furthermore, patients with KELIM ≥1 and CRS3 had significantly higher PFS compared to other groups(median PFS 28.27 months vs 17.66 months for KELIM ≥1/CRS 1/2; 17.13 months for KELIM <1/CRS 3; and 14.53 months for KELIM <1/CRS 1–2, p = 0.003). Conclusion The biochemical KELIM score correlated with the surgical pathologic CRS score and may predict pathological response to chemotherapy. This information can be utilized to tailor and personalize treatment in patients with advanced ovarian malignancy.