Background:Bevacizumab with chemotherapy followed by bevacizumab was approved in 2018 for the first-line (1L) treatment of patients with ovarian cancer (OC). However, little is known about the real-world experience of OC patients treated with bevacizumab.Methods: This SEER-Medicare retrospective cohort study included females u2265 66 years, OC (stage II-IV) diagnosis between 2009 and 2015, who continued bevacizumab or observation alone after 4 u2013 10 cycles of 1L platinum-based chemotherapy with or without bevacizumab. The primary outcome was overall survival (OS), measured from 1L treatment initiation to death. Safety events of interest included thrombosis, hemorrhage, stroke, and gastrointestinal perforation. Inverse probability of treatment weighting (IPTW) incorporated 32 demographic and prognostic characteristics. Cox proportional hazards models with IPTW were used to compare outcomes.Results:In this cohort (N=2262), 66 (3%) patients received bevacizumab maintenance. Mean age (u00b1SD) was 74.6 (6.2) years, 89% were Stage III or IV, and 26.9% of patients had u22651 co-morbidity. Patients treated (preapproval) with 1L maintenance bevacizumab increased from 0.3% in 2009 to 4.1% in 2015. Compared to observation alone, median OS in patients treated with bevacizumab maintenance was 43.6 vs 37.9 months (adjusted hazard ratio HR=0.83 95% CI: 0.50 u2013 1.36). Among those who received >7 cycles of bevacizumab, OS was longer, though not significantly, compared to observation alone (aHR = 0.62 95% CI: 0.32-1.18). Initiation of nonplatinum chemotherapy within 12 months occurred in 36.4% of observation only and 20.9% of bevacizumab maintenance patients. Compared to observation alone, specified safety events were not higher with bevacizumab maintenance, aHR: 0.94 0.49 u2013 1.82.Conclusions: Survival among this small cohort of elderly OC patients in this real-world study is consistent with that observed in trials of 1L bevacizumab maintenance. First-line maintenance bevacizumab therapy appears to provide modest survival benefit