Characterization of ovarian cancer survival by histotype and stage: A nationwide study in Norway

Abstract Contemporary population‐based data on ovarian cancer survival using current subtype classifications and by surgical status are sparse. We evaluated 1‐, 3‐, 5‐ and 7‐year relative (and overall) survival, and excess hazards in patients with borderline tumors or invasive epithelial ovarian cancer diagnosed 2012 to 2021 in a nationwide registry‐based cohort in Norway. Outcomes were evaluated by histotype, FIGO stage, cytoreduction surgery and residual disease. Overall survival was evaluated for non‐epithelial ovarian cancer. Survival of women with borderline ovarian tumors was excellent (≥98.0% 7‐year relative survival). Across all evaluated invasive epithelial ovarian cancer histotypes, 7‐year relative survival for cases diagnosed with stages I or II disease was ≥78.3% (stage II high‐grade serous). Survival for ovarian cancers diagnosed at stage ≥III differed substantially by histotype and time since diagnosis (eg, stage III, 5‐year relative survival from 27.7% [carcinosarcomas] to 76.2% [endometrioid]). Overall survival for non‐epithelial cases was good (91.8% 5‐year overall survival). Women diagnosed with stage III or IV invasive epithelial ovarian cancer and with residual disease following cytoreduction surgery had substantially better survival than women not operated. These findings were robust to restriction to women with high reported functional status scores. Patterns for overall survival were similar to those for relative survival. We observed relatively good survival with early stage at diagnosis even for the high grade serous histotype. Survival for patients diagnosed at stage ≥III invasive epithelial ovarian cancer was poor for all but endometrioid disease. There remains an urgent need for strategies for risk reduction and earlier detection, together with effective targeted treatments.