PRESENTING FEATURES OF MONOCLONAL GAMMOPATHIES - AN ANALYSIS OF 684 NEWLY-DIAGNOSED CASES

Objectives. The clinical, laboratory and radiologic features at diagno sis of 684 newly diagnosed patients with monoclonal gammopathy were re vised in order to underline the differences between monoclonal gammopa thies of undetermined significance (MGUS) and stage I multiple myeloma (MM). Design. Patients were screened for inclusion in a prospective c ontrolled protocol for treatment of MM. Those having serum or urine mo noclonal component (MC) were diagnosed as MM when they demonstrated os teolysis and/or bone marrow plasma cells (BMPC) > 20%; patients not fu lfilling these criteria were considered MGUS. Setting. Patients were r ecruited from 24 general or university hospitals from the departments of internal medicine, haematology and medical oncology. Subjects. Seve n-hundred-and-fifty were enrolled between january 1986 and March 1990; 684 (343 MGUS and 341 MM) were able to be evaluated for this study an d 78 were stage I MM. Interventions. Complete clinical, radiologic and laboratory work-up was carried out at the referral centres. Main outc ome measures. The main outcome expected was the confirmation that BMPC > 20% could reliably differentiate stage I MM from MGUS. Results. At a median follow-up of 36 months (minimum follow-up: 18 months), MGUS h ad a lower progression rate to overt MM, longer overall survival and d ifferent causes of death than stage I MM. Further differences concerne d erythrocyte sedimentation rate (28 vs. 47, P < 0.001), per cent redu ction of normal immunoglobulin (86 vs. 60%, P < 0.001), serum MC (1.6 vs. 2.2 g dl-1, P < 0.001) and thymidine kinase level (3.3 vs. 4.5 mU ml-1, P < 0.05). Conclusions. The study suggests that 20% BMPC can be taken as a safe cut-off point at which to differentiate MGUS from earl y MM and outlines a few simple parameters which can be of diagnostic a id.