An analysis of which subgroups of multiple myeloma patients, divided according to beta(2)-microglobulin and plasma cell labeling index, benefit from high dose vs conventional chemotherapy

Background and Objectives. The clinical advantage of high-dose therapy (HDT ) over standard treatment for multiple myeloma (MM) patients has been recen tly assessed. Which patient subgroups benefit most from this approach is un clear. Design and Methods. To address this issue, the outcome of 54 patients under 55 years old treated with HDT was compared with that of 101 age-matched co ntrols selected from 390 patients who received standard melphalan and predn isone (MP) chemotherapy in a national multi-center trial (M90 protocol). Results. The complete response (CR) rate was 50% in the HDT group compared to 5% in the MP group. Event-free survival (EFS) was three times longer for the HDT patients (median 34.5 vs 12.2 months, p<0.0001), though the contro ls enjoyed a prolonged survival after relapse, and hence there was no stati stically significant difference in OS. Overall survival (OS) was analyzed i n relation to two major prognostic factors: beta(2)-microglobulin (beta(2)- M) and bone marrow plasma cell labeling index (LI). HDT significantly impro ved OS in poor prognosis patients with a high LI (>1.2%), (median 49.5 vs 3 2.5 months, p<0.03), whereas it did not prolong OS in poor prognosis patien ts with high beta(2)-M (> 3 mg/L). Interpretation and Conclusions. In conclusion, HDT has a major impact on CR and EFS, and is the treatment of choice for patients with a high LI. Alter native strategies should be adopted in poor prognosis patients with high be ta(2)-M. (C)1999 Ferrata Storti Foundation.