Complete remission rate and outcome after intensive treatment of 177 patients under 75 years of age with IgG myeloma defining a circumscribed disease entity with a new staging system

Because the presence of IgG paraprotein in the blood is clear cut, it makes IgG myeloma a more circumscribed disease than myeloma as a whole in which to study treatment efficacy, particularly relating to complete remission (CR). Between May 1989 and December 1997, 177 consecutive patients with IgG myeloma who were <75 years old were seen, of whom 153 entered a sequential therapy (ST) programme of initial courses of C-VAMP infusional chemotherapy (IC), high-dose treatment (with or without stem cell rescue) (119 patients) and maintenance interferon (87 patients). 74/153 (48.4%) patients entered CR. Median overall survival (OS) and event-free survival (EFS) were 4.9 and 2.1 years, respectively. Multivariate analysis at presentation showed OS was significantly prolonged for β₂M <2.7mg/l and age <median 52, whilst β₂M <2.7 mg/l and Hb >8.5 g/dl predicted for longer EFS. For CR patients, age <median 51 years, absence of Bence-Jones proteinuria (BJP), male sex and white blood cells (WBC) <7 x 10⁹/1 predicted for a longer OS. Longer length of first CR was predicted by absence of BJP at presentation (P = 0.03) and fewer than five courses of IC (P = 0.02) to attain CR. We have therefore been able to refine the use of ST in IgG myeloma, redefine CR as a 'macro' endpoint, and propose a new staging system for IgG myelomas. Analysis of 41 comparable IgA patients showed IgG to be a distinct entity.