ObjectiveUnderstanding real-world treatment patterns and proportions of eligible patients in each line of treatment is imperative to inform future clinical trial designs and multi-line treatment algorithm development. MethodsWe conducted a retrospective observational cohort study of adult women who received first-line (1 L) therapy for r/mCC between 01 September 2014 and 31 December 2019, using The US Oncology Network electronic health records and chart review data. Patients were followed to 31 December 2020. Patient demographic and clinical characteristics, treatment patterns, and clinical outcomes were assessed descriptively. ResultsA total of 262 patients with r/mCC met study inclusion criteria (mean age = 53 years). The majority of patients in 1 L received platinum-based chemotherapy doublet plus bevacizumab (66%) or chemotherapy doublet alone (24%). Nearly half the patients (48%) completing 1 L received 2 L therapy. Among these patients, there was no consistent 2 L treatment of choice. Overall median time to treatment discontinuation was 3.5 months from 1 L treatment initiation, and median overall treatment-free interval was 2.1 months from 1 L discontinuation. Besides elevated serum creatinine, abnormal BMI indicated a directional trend for lower likelihood of receiving 2 L. Other predictors may include no prior bevacizumab, worse ECOG, and earlier disease prevention. Conclusions>50% of the patients who initiated 1 L treatment did not receive 2 L therapy, highlighting the need for novel and effective treatment options. As the treatment landscape continues to evolve, we anticipate that more patients will live longer with more treatment options across multiple lines of therapies in the r/mCC setting.