Abstract
<title>Abstract</title> <p>Background Ribociclib combined with endocrine therapy (ET) is a standard of care for hormone receptor-positive (HR+)/HER2-negative advanced breast cancer. However, real-world evidence from nationally regulated healthcare systems remains limited. We aimed to evaluate survival outcomes of ribociclib plus ET in routine clinical practice using data from a national cohort in Uruguay. Methods We conducted a retrospective, national cohort study including 562 patients with advanced HR+/HER2-negative breast cancer treated with ribociclib plus ET between 2022 and 2024. Ribociclib was administered as first-line therapy in 419 patients and as second-line therapy in 143 patients. Survival outcomes were estimated using the Kaplan-Meier method and compared using log-rank tests. Multivariable Cox proportional hazards models were fitted to identify independent predictors of progression-free survival (PFS) and overall survival (OS). Results Median PFS was 12 months in first-line and 10 months in second-line patients (p = 0.005). The 24-month OS rate was approximately 75%. In multivariable analysis, second-line treatment (HR 1.36; 95% CI: 1.08–1.71; p = 0.009) and hepatic metastases (HR 1.40; 95% CI: 1.08–1.81; p = 0.011) were independent predictors of worse PFS. For OS, hepatic metastases was the only independent prognostic factor (HR 2.08; 95% CI: 1.43–3.03; p < 0.001). Conclusion In this national real-world cohort, ribociclib plus ET demonstrated meaningful clinical benefit. Hepatic metastases was the only independent predictor of worse overall survival, and line of treatment independently predicted progression-free survival.</p>