Intensive therapy for multiple myeloma in patients younger than 60 years. Long-term results focusing on the effect of the degree of response on survival and relapse pattern after transplantation.

BACKGROUND AND OBJECTIVES: From 1994 to 1997 we conducted a population-based, prospective study on intensive therapy in newly diagnosed symptomatic myeloma patients younger than 60 years, comparing their survival to that of a conventionally treated historic population. Long-term results are presented, including the impact of the degree of response on survival and relapse pattern after transplantation. DESIGN AND METHODS: The prospective population was formed of 397 patients and the historic population of 313 patients. Both populations were calculated to comprise more than 75% of the expected number of new cases. RESULTS: After a median follow-up of 7 years survival was longer in the prospective population than in the historic one (median 60 versus 39 months; p=0.0002). When comparing only patients eligible for intensive therapy the median survival was 63 versus 44 months (p<0.0001). Attaining a complete response was associated with prolonged event-free survival but not overall survival. The pattern of relapse after transplantation was heterogeneous but could be divided into four major groups; insidious, classical, plasmacytoma form and transformed disease. The median survival after relapse was 29 months. The relapse pattern and time to relapse predicted outcome. Patients relapsing with an insidious or classical form of disease with skeletal events only, or after a long lasting first response were likely to respond well to conventional salvage therapy. In contrast, relapse with multiple symptoms, transformed disease or a short duration of first response implied bad prognosis. INTERPRETATION AND CONCLUSIONS: The relapse pattern after autologous transplantation is heterogeneous and response to salvage therapy is variable. The degree of response and event-free survival after transplantation are not reliable surrogate markers for survival.