Similar survival outcomes in patients with biclonal versus monoclonal myeloma: a multi-institutional matched case-control study.

ABSTRACT

Multiple myeloma is a plasma cell malignancy characterized by clonal proliferation of plasma cells in the bone marrow and associated organ damage. Usually, patients with myeloma present with a single monoclonal protein in serum and/or urine constituted by one heavy chain and one light chain. In less than 5% of the patients, more than one monoclonal protein can be identified. The aim of our retrospective multicenter matched case-control study was to describe the characteristics of cases with biclonal myeloma and compare them against a control group of monoclonal myeloma patients matched by age, sex, and year of diagnosis. A total of 50 previously untreated cases with biclonal myeloma and 50 matched controls with monoclonal myeloma were included in this study. The controls were matched (11) for age, sex, year of diagnosis, and participating center. There were no differences in the rates of anemia (52 vs. 59%; p = 0.52), renal dysfunction (36 vs. 34%; p = 0.83), hypercalcemia (9 vs. 16%; p = 0.28), or presence of lytic lesions (23 vs. 16%; p = 0.38) between groups. Similarly, there was no difference in the rates of overall response to therapy (85 vs. 90%; p = 0.88) or survival rates of cases with biclonal myeloma and controls with monoclonal myeloma (4-year survival 72 vs. 76%; p = 0.23). Results of our study suggest that patients with biclonal myeloma have similar response and survival rates than patients with monoclonal myeloma.