A plea to overcome the concept of 'staging' and related inadequacy in multiple myeloma

From a retrospective multivariate study on 107 multiple myeloma (MM) patients, serum β₂-microglobulin (β₂M) proved to be the best prognostic discriminator, better than each of the currently used staging systems (Durie and Salmon's [DS], Merlini, Waldenstrom and Jayakar's [MWJ] and the British Medical Research Council's [BMRC]). The predictive ability of each staging system is better improved by combining consideration of β₂M as a continuous rather than a binary variable (even at its best prognostic cut-off). The combination of BMRC with β₂M demonstrated the highest prognostic value, followed by those involving DS or MWJ. Ease and measurability of clinical parameters at diagnosis, parametric type of statistical model assumed for description of survival, and supply of direct estimate of expected survival are the characteristics of the MWJ system that suggest it is best able to integrate β₂M correctly in a prognostic index. The basic concepts and the clinical use of the available staging systems for MM are criticized along the following lines: a) the need to include new and homogeneously weighted parameters in future prognostic systems; b) the lack of direct correspondence between treatment requirements (according to stage) and available therapeutic resources; c) evidence of the rough stratification of the actual survival expectancy, as permitted by the current staging systems. A direct, and as accurate as possible estimate of prognosis - based on easy and measurable parameters evaluable at diagnosis - should replace the current classification of patients according to stages. This estimate should mark the clinical evaluation at diagnosis, should flexibly indicate treatment even according to different protocols or centers, and should allow very accurate statistical corrections for different survival expectancy at diagnosis when evaluating different treatments in clinical trials.