Association of the European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) Scores with Guideline Recommendations in Breast Cancer

OBJECTIVES: To evaluate the association between European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) scores and treatment recommendations from European Society for Medical Oncology, National Comprehensive Cancer Network (NCCN), and American Society of Clinical Oncology (ASCO) in curative and metastatic breast cancer (BC), and to assess inter-guideline concordance. METHODS: We conducted a comparative review of 47 systemic BC therapies with published ESMO-MCBS scores (accessed 30 June 2025). Guideline recommendations from ESMO, NCCN, and ASCO were extracted from the most recent versions and harmonized into ordinal tiers. Associations between MCBS scores and recommendation categories were evaluated using Fisher's exact test and Spearman's rank correlation in the palliative setting. Curative therapies were analyzed descriptively due to limited variability. RESULTS: = 9), most therapies received an MCBS grade A and top-tier guideline endorsement. CONCLUSIONS: Alignment between ESMO-MCBS and guideline recommendations is moderate and framework-dependent, strongest with NCCN in metastatic BC. Discordance primarily reflects differences between magnitude-of-benefit thresholds and evidence-certainty frameworks. ESMO-MCBS may serve as a complementary tool to enhance value-based clinical and policy decision-making.