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] Among 38 palliative therapies, 40% achieved high clinical benefit (MCBS 4-5). A significant association was observed between MCBS scores and NCCN recommendations ( = 0.003; ρ = 0.48), with 62% of NCCN Category 1 therapies demonstrating high benefit versus 13% in other categories. No significant associations were observed with ASCO ( = 0.101; ρ = 0.18) or ESMO guideline recommendations ( = 0.073; ρ = 0.19). Inter-guideline concordance was strongest between ASCO and ESMO ( = 0.033; ρ = 0.48). In the curative setting ( = 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.