Introduction CA-125 ELIMination rate constant K (KELIM), a biomarker for assessing prognosis in high-grade serous ovarian carcinoma (HGSOC), was rarely analyzed among Japanese patients. Meanwhile, dose-dense paclitaxel plus carboplatin (ddTC) is reportedly superior to conventional paclitaxel plus carboplatin (cTC) in patients with poor prognosis defined by KELIM and surgical outcomes. Therefore, we investigated the utility of KELIM among Japanese HGSOC patients.

Methods We included patients with HGSOC at our institution in 2012-2021. KELIM was calculated by CA-125 trend within first 100 days of adjuvant chemotherapy (AC)/neo-adjuvant chemotherapy (NAC) and classified favorable (≥1.0) or unfavorable (<1.0). We further defined two cohorts: patients with favorable KELIM and complete surgical outcome (Good), and patients with unfavorable KELIM or residual tumors (Poor). Progression-free survival (PFS)/overall survival (OS) were assessed.

Results Of 259 eligible patients with HGSOC, 152 and 107 patients underwent primary debulking surgery (PDS) with AC and interval debulking surgery (IDS) after NAC, respectively. AC/NAC included cTC (n=84) or ddTC (n=175). Favorable KELIM significantly contributed to longer PFS/OS than unfavorable KELIM (p<0.05). Unfavorable KELIM in NAC correlated with residual tumor at IDS (Odds Ratio, 4.53; 95% CI, 1.71-12). Furthermore, 129 and 130 patients were in Good and Poor cohorts which had significantly different PFS/OS (p<0.01). Among Poor cohort, ddTC after PDS showed longer PFS/OS than cTC (HRs, 0.595/0.604; 95% CIs, 0.354-0.998/0.319-1.143), but not in those underwent IDS.

Conclusion/Implications KELIM would indicate prognosis in Japanese patients with HGSOC. Moreover, ddTC might be effective in HGSOC patients with poor survival potential predicted by KELIM and surgical outcomes.