Ovarian cancer survival by residual disease following cytoreductive surgery: a nationwide study in Norway

Abstract

Background: Residual disease (RD) following cytoreductive surgery is prognostic for epithelial ovarian cancer (EOC) patients. Few studies have evaluated RD and survival by tumor histotype and across continuous RD diameter. Methods: 2608 individuals with stages III-IV invasive EOC diagnosed between 2013 and 2022 were identified using the Cancer Registry of Norway. In flexible parametric models, we compared excess mortality comparing RD versus no macroscopic residual disease (NMRD); systemic anti-cancer therapy was evaluated in a sub-cohort from 2019. Excess mortality was assessed across continuous RD size using restricted cubic splines. Results: Among 1849 patients with cytoreductive surgery, survival was worse for individuals with RD (vs. NMRD), excess hazard ratio (EHR) = 2.62 (95% confidence interval = (2.27–3.01)); no heterogeneity was observed by histotype (p = 0.21). Patients with 0.1–0.4 cm RD had 2-fold higher risk of death (EHR = 2.09 (1.63–2.68)) relative to women with NMRD; ~3-fold higher risk was observed for all other categories (e.g., 0.5–0.9 cm, EHR = 2.97 (2.26–3.89); 3.0–20 cm, 2.75 (2.05–3.70)). No significant difference in three-year survival was observed across continuous RD diameter (p ≥ 0.17). NMRD was associated with better survival regardless of neoadjuvant chemotherapy. Discussion: Achieving NMRD resulted in the best survival outcomes. Among patients with RD, we observed no significant difference in survival by RD diameter.