Multiple myeloma (MM) is a malignant blood cancer characterized by proliferation of plasma cells in bone marrow that is mainly composed by inflammatory cells. A prognostic effect can be assessed as consequence of alterations in peripheral blood leukocytes and the ratio between blood cells have been pointed as prognosis marker of several tumors.

To evaluate the prognostic significance of lactate dehydrogenase (LDH) and the ratios between neutrophil-to-lymphocyte (NLR), monocyte-to-lymphocyte (MLR) and platelet-to-lymphocyte (PLR), and associations between them, on progression-free survival (PFS) and overall survival (OS) in MM.

We retrospectively analyzed 117 data of newly MM patients diagnosed between Jun/2008-Dec/2018 from two hospitals in Porto Alegre/RS/Brazil. The results of LDH pretreatment (3 to 7 days) and absolute values of leukocytes and platelet were collected to calculate NLR, MLR and PLR. Area under curve (ROC) determined the cut off value associated to death. Univariate and multivariate Cox proportional hazard analyses assessed the relationship of the MRL and LDH to PFS and OS.

MLR ≥0.43 and LDH ≥292.5 were associated with shorter OS (40.7 vs 80.4 months; p < 0.0001; 43.8 vs 85.7 months; p = 0.004) and the multivariate analysis showed that these RML and LDH values are independent prognostic factor for predicting OS (p = 0.033 and 0.008, respectively). The association of higher RML and LDH values present a RR 3.61 to death (p = 0.02). Conclusion: LDH and MLR can predict clinical outcomes in newly diagnosed MM patients and may serve as a simple and cost-effective prognostic marker in the routine practice.