Breast cancer is one of the most common types of cancer among women across the world. Endocrine therapy is one of the established treatments for breast cancer, but recent analysis suggests additional benefits when endocrine therapy is combined with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor (ribociclib). This study aims to assess the overall survival rate with ribociclib plus endocrine therapy in women with breast cancer. 

This is a randomized study that included a total of 672 women with advanced hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer. The participants were randomly assigned to receive either ribociclib or placebo in combination with endocrine therapy. The primary outcome was overall survival.

Out of 672 patients, 335 were assigned to the ribociclib group and 337 to the placebo group. A total of 83 deaths (24.8%) in the ribociclib group and 109 deaths (32.3%) in the placebo group were reported. The addition of ribociclib to endocrine therapy resulted in a significant increase in the overall survival of endocrine therapy alone. The estimated overall survival for the ribociclib and placebo groups after 42 months was 70.2% and 46.0%, respectively.

The research concluded that the combination of ribociclib and endocrine therapy significantly improved the overall survival rates among breast cancer patients than endocrine therapy alone.