Time Toxicity of Endocrine-based Oral CDK4/6 Inhibitor Therapies

Adjuvant endocrine therapy with CDK4/6 inhibitors necessitates regular visits, lab assessments and side effect management, currently conducted primarily at breast cancer centers in Germany. This retrospective analysis estimates the potential travel distances, times and CO ₂ emissions associated with centralized therapy management of adjuvant CDK 4/6 inhibitor application. Eligible patients for ribociclib or abemaciclib therapy were retrospectively identified from 5053 early breast cancer cases at the university hospitals of Ulm, Lübeck and Tübingen, using the monarchE and NATALEE criteria. Travel times were calculated assuming 24 visits over three years for ribociclib and 18 visits over two years for abemaciclib. Of the HR+/HER2- cohort, 1432 (38%) were potentially eligible for adjuvant CDK4/6 inhibitors, with 1080 patients included, based on available postal codes. Median travel distances and times for Ribociclib (3 years) were 1200 km (24.0 hours driving; 176.0 kg CO ₂ emissions; 50.4 hours by public transport; 72.0 kg CO ₂ emissions) and 900 km (18.0 hours driving; 132.3 kg CO ₂ emissions; 37.8 hours by public transport; 54.0 kg CO ₂ emissions) for abemaciclib (2 years). Despite its retrospective limitations, this analysis provides valuable insight into the impact of centralized care on travel time and CO ₂ emissions for oral cancer therapies in Germany. As the use of oral therapies increases, clinicians, patients, policymakers and the pharmaceutical industry should jointly develop strategies to optimize the safety, feasibility, and efficacy of oral therapies.