OBJECTIVES: Recently the ESMO Magnitude of Clinical Benefit Scale (ESMO-MCBS) have been introduced. The scale is supposed to assist decisions about value and cost-effectiveness of new cancer therapies. This is done by classifying therapeutic advances according to their relative clinical benefit according to pre-defined criteria. The objective of the present study was to investigate the scale from a health economics perspective. METHODS: We conducted a critical appraisal of the building blocks of the scale in order to assess potential limitations to using the instrument to inform policy. RESULTS: Several issues that makes the scale problematic were identified. Three key areas of concern were:  

1. ESMO-MCBS uses different scales depending on if the intent of the therapy of to be curative or not. It is impossible to compare two cancer treatments which both have effect on survival and quality of life if the intension of the two therapies are different, yet they would compete for the same resources within the health care system.  
2. The ranking used is created based on expert opinion. It is unclear how these rankings would relate to the preferences of the patients or the general public.
3. The scale relies on clinical trials as the evidence base. What matters for reimbursement agencies, payers and health care providers is how well the new treatment opportunity performs in clinical practice, in relation to existing therapeutic alternatives.   

CONCLUSIONS: There are limitations to the ESMO-MCBS at present as a measure of value. One important aspect that would merit further study is to validate how well the scale is able to discriminate between more and less valuable therapies as perceived by reimbursement bodies, by for instance comparing the rankings of therapies according to ESMO-MCBS to rankings based on estimated gains in survival and quality-adjusted survival.