CDK4/6 inhibitor plus endocrine therapy for advanced breast cancer: results from a web-based survey in Japan.

Background: Though efforts have been made toward standardizing access to quality cancer care in Japan, there are still geographical and institutional disparities in the level of cancer care availability. We investigated the utilization of cyclin-dependent kinase 4/6 inhibitors plus endocrine therapy (CDK4/6i+ET) as first-line (1 L) treatment for hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) in Japan.

Research Design And Methods: This cross-sectional survey included physicians who had treated ≥3 1 L patients with HR+/HER2- ABC in the past year.

Results: Of 41,695 physicians invited, 300 were included in the analysis. The mean percentage share of CDK4/6i+ET and ET monotherapy was 38.3% and 42.2%, respectively. Common challenges facing CDK4/6i+ET prescription were adverse reaction management, prohibitive cost, and a preference for ET monotherapy for treating elderly patients. Key solutions included reducing the burden of adverse reaction management, improving financial support, and preparing educational videos for medical staff.

Conclusions: The study concluded that CDK4/6i+ET is not well established as a 1 L option in Japan as of 2022. More effective ways of creating awareness and supportive tools are needed for CDK4/6i+ET to be adopted as standard of care in Japan.

Trial Registration Number: UMIN000050760.