Multiple Myeloma (MM) is a hematological disease predominantly affecting elderly patients. The complexity of current treatment necessitates individualized approaches. Therein, functional assessment (FA) tools, such as the Revised Comorbidity Index (R-MCI) at our University- and Comprehensive Cancer Center Freiburg, play a crucial role. This study aimed to determine (a) the implementation of the R-MCI in our MM-tumor board (MM-TB), (b) its impact on treatment guidance at baseline and (c) potential changes during follow-up. This exploratory study investigated R-MCI coverage and distribution in a cohort of patients with multiple TB presentations. Among them, a follow-up patient cohort undergoing subsequent MM-therapy was analyzed to determine treatment adjustments and changes in patients' condition measured by R-MCI alterations. During our 3-year assessment period, 565 patients were presented in our MM-TB, totaling 1256 TB-presentations. In the multiple TB presentation cohort, the median number of TB presentations was 3 (range: 2-12). R-MCI scores within the MM-TB were available in 94%, whereas in 6%, the R-MCI had not been integrated. Among these, potential failure to identify the need for treatment modifications was determined. In the follow-up cohort, patient characteristics were typical for referral/university centers. Dose reductions were performed in 55% and were more prevalent among patients with ≥ 4 vs. lesser TB presentations. Most patients (55%) showed a fitness stabilization or improvement via follow-up R-MCI. R-MCI integration in MM-TB exceeded >
90%, indicating its successful integration for treatment support. Our results underscore its value in guiding therapy decisions, providing a comprehensive assessment beyond age considerations.