Stage IV Ovarian Cancer Is Not Uniformly Lethal: Two Subgroups With Stage II ‐Like Outcomes Identified in Large Retrospective Cohorts

BACKGROUND: The International Federation of Gynecology and Obstetrics (FIGO) staging system for advanced ovarian cancer has remained largely static since 2014, with stage IV subdivided into IVA and IVB without further stratification. Emerging evidence suggests substantial prognostic heterogeneity within stage IV, yet large-scale validation remains limited. METHODS: We analyzed 28,010 patients from the Surveillance, Epidemiology, and End Results (SEER) database (2010-2022) and 1175 from the Sun Yat-sen University Cancer Center (SYSUCC) (2010-2026). Propensity score matching (1:1) balanced baseline characteristics. Overall survival (OS) was compared across subgroups. We defined IVA-T1a as patients meeting FIGO IVA criteria with intra-abdominal disease limited to one ovary (intact capsule). We defined IVB-ILNT2 as stage IVB with metastasis confined to a single extra-abdominal lymph node station and intra-abdominal disease ≤ T2. IVB patients were stratified by metastatic pattern and surgical outcome. RESULTS: In SEER, IVA-T1a patients (n = 49) showed no OS difference versus stage II (HR 1.08, 95% CI: 0.95-1.23, p = 0.250), but significantly better survival than stage IIIA (HR 1.35, 95% CI: 1.08-1.62, p = 0.024). Findings were validated in SYSUCC (IVA-T1a n = 15; vs. stage II p = 0.638, vs. IIIA p = 0.026). Among IVB patients, those with single-station lymph node metastases achieving R0/R1 resection (n = 152) had median OS of 29.0 months, comparable to stage IIIC patients (HR 1.08, p = 0.872). In SYSUCC, IVB-ILNT2 subgroup (n = 65) demonstrated survival comparable to stage II (p = 4e-04 vs. other IVB) and significantly better than stage IIIA. CONCLUSIONS: These findings suggest that such patients may have a more favorable prognosis than implied by their current stage designation and underscore the need for prospective validation to determine whether treatment de-escalation could be considered in these specific subsets without compromising outcomes. Future FIGO revisions should consider refined classification incorporating intra-abdominal tumor burden and metastatic pattern, pending consistent validation across multiple independent populations.