Prognostic factors in multiple myeloma: a new staging system based on clinical and morphological features

A new staging system for multiple myeloma based on clinical and morphological features has been developed on the analysis of 190 patients. A score of "1" was assigned to each of the following clinical data, referred at the time of diagnosis, and selected by multivariate analysis: bone marrow plasma cells more than 30%, haemoglobin less than 110 milligrams, lytic bone lesions of degree 2 or 3, serum beta 2-microglobulin levels higher than 678 nmol/l, and presence of Bence-Jones proteinuria. Therefore, the score for each patient ranged from 0 to 5, and three clinical stages were provided: I = 0 or 1, II = 2 or 3 and III = 4 or 5. Substratification into A and B for each clinical stage was performed using multiple myeloma cellular score, calculated by the formula: total bone marrow myeloma cells per 500 cells x 0.752 + bone marrow plasmablasts per 500 cells x 0.709. Substage A corresponded to multiple myeloma cellular score value lower than 0.300, and substage B to a value greater than 0.300. Significant differences were found in median survivals (P less than 0.0001), in survival curves (P less than 0.0001), and in responses to treatment (P less than 0.0001) among the six staged groups. The use of this staging system for multiple myeloma could offer new prognostic information and could better quantify the picture of the disease in each patient. The substaging according to morphological criteria seems very useful in diminishing or eliminating the great prognostic variability observed within the same clinical stage. Confirmatory studies are required to validate this new staging system for multiple myeloma.