Clinical course of patients with relapsed multiple myeloma.

OBJECTIVE: To study the clinical course of patients with multiple myeloma (MM) that relapses after initial therapy. PATIENTS AND METHODS: Patients with MM, seen at the Mayo Clinic in Rochester, Minn, between January 1, 1985, and December 31, 1998, were identified from a prospectively maintained database. Our study population consisted of 578 patients with newly diagnosed MM who were followed up and monitored throughout their clinical course at our institution.
RESULTS: The median age of the 578 patients with MM was 65 years (range, 26-92 years); 228 patients (39%) were women. The median follow-up of 71 surviving patients was 55 months (range, 0-202 months). The overall survival (OS) for the 578 patients at 1, 2, and 5 years was 72%, 55%, and 22%, respectively; the median OS from initial therapy was 28.4 months. The median OS of 355 patients who experienced relapse after initial treatment was 17.1 months from initiation of the second therapy, and 84% died within 5 years. The duration of response decreased consistently with each successive regimen. Patients with a high plasma cell labeling index (> or = 1.0%), low platelet count (< 150 x 10(9)/L), high creatinine level (> or = 2.0 mg/dL), and low albumin level (< 3.0 g/dL) had a poorer prognosis.
CONCLUSIONS: Our study revealed decreasing response duration with increasing number of salvage regimens, probably reflecting acquired drug resistance and an increasing proliferative rate of the myeloma cells. Patients who experienced relapse after initial treatment and received salvage therapy had a median survival of nearly 1.5 years. This must be remembered when making treatment decisions for these patients and must be factored in when assessing the efficacy of new therapies.