Long-Term Survival in High-Grade Serous Ovarian Cancer Compared With the General US Population: A 30-Year Landmark Analysis.

Purpose: To compare mortality risk among long-term survivors of high-grade serous ovarian cancer (HGSOC) with that of the general U.S. population and to examine how mortality and recurrence trends have evolved under changing treatment approaches. Material and Methods: This is a retrospective cohort study including patients with histologically confirmed HGSOC treated at a single referral cancer center from 1991 to 2022. Mortality risk, expressed as standardized mortality ratios (SMRs, ratio of observed deaths in the study population to expected deaths in an age-matched U.S. population) was assessed at diagnosis and yearly on patients without events (disease persistence, recurrence, or death from any cause). Results: A total of 2,074 consecutive patients were included. Median follow-up was 12.5 years [interquartile range (IQR) 11.7-13.8]. Most patients were stage III (1396, 69.2%), 1299 (62.8%) underwent primary cytoreductive surgery, and 1688 (87.4%) received platinum-taxane as first-line therapy. At diagnosis, the mortality rate was 7.40 times higher than in the general population [95% confidence interval (CI) 7.04-7.77]. By 7 event-free years, the 95% confidence interval for the SMR included 1 for the first time, and at 10 years, the SMR was 1.05 [95% CI 0.72-1.49]), indicating no statistically significant excess mortality compared to the general population. In those event-free at 10 years, the 5-year cumulative incidence of ovarian cancer-related deaths (8.2% [95% CI 4.2-16.0]) was comparable to that of non-ovarian cancer-related deaths (6.3% [95% CI 2.9-13.8]). Conclusions: In this cohort, mortality risk steadily declined for patients who remained event-free, approaching that of the general population by 7 years post-diagnosis. These results emphasize the importance of individualized, long-term follow-up to address both recurrence risk and survivorship needs.