Clinical Characteristics Of Multiple Myeloma Patients With Extramedullary Disease

ObjectiveIn multiple myeloma (MM), plasma cell is usually restricted to the bone marrow. But a small number of patients will develop extramedullary disease (EMD) at diagnosis or during follow-up, showing a different clinical characteristics and a dismal prognosis. This study aims to analyse the incidence, clinical features, prognosis and relationship with previous therapies of EMD in MM patients in our country. The different definitions of the EMD were also compared.MethodsThe records of 834 patients with MM in our hospital between 1993 and 2013 were retrospectively reviewed.ResultBecause of the divergence in the definition of EMD, we applied the strict EMD (sEMD) definition in analysis first, and then discussed the clinical significance of the bone-related EMD (bEMD). The results are divided into the following two parts:① Analysis of the sEMD showed:The incidence of sEMD was 4.8%(40cases) at diagnosis, and 3.4%(28 cases) during follow-up. Compared with patients presenting no sEMD, patients with sEMD at diagnosis had remarkably higher lactate dehydrogenase (median 299.2U/L versus 185U/L, P=0.003), and more occurrences of P53 deletion by fluorescence in situ hybridization (FISH) of the bone marrow samples (34.5% versus 11.9%, P=0.037). Multivariate analysis demonstrated that sEMD spread during follow-up was correlated with sEMD presentation at diagnosis, IgD subtype and P53 deletion by FISH (HR were16.1,6.29and 2.44 respectively, P<0.05). The risk of sEMD spread was not increased by previous autologous stem cell transplantation (ASCT), thalidomide/lenalidomide, or bortezomib. Multivariate analysis showed that sEMD was an independent negative prognostic factor of MM. The median overall survival (OS) of patients with or without sEMD was 16.5 months versus 40 months (P<0.001), and the median time to progression (TTP) of the two groups was 11.5 months versus 25 months(P<0.001). ② Analysis of bEMD showed: The incidence of bEMD was 4.8% at diagnosis, and 0.5% during follow-up. Patients with bEMD at presentation showed significant lower level of lactate dehydrogenase and higher overall response rate (ORR) compared with sEMD patients. And the ORR was comparable to the patients’ without EMD. As to the prognosis of patients not receiving ASCT, the median OS of patients with bEMD, sEMD and without EMD was 37.5 months,14.0 months and 38.0 months respectively. The median TTP of the three groups was 27.0 months,11.5 months and 22.0 months respectively. The outcome (both OS and TTP) of patients with bEMD at presentation was comparable to the patients without EMD, and was significantly better than the patients with sEMD (P<0.05)。ConclusionMM patients presenting sEMD at diagnosis showed remarkably higher lactate dehydrogenase and prevalence of P53 deletion detected by FISH. The risk of sEMD spread during follow-up was correlated with sEMD presentation at diagnosis, IgD subtype and P53 deletion detected by FISH, but not previous ASCT, thalidomide/lenalidomide, or bortezomib. In the aspect of prognosis, multivariate analysis showed that sEMD at diagnosis was an independent negative prognostic factor in MM. It seemed that bEMD only conveys no impact on the prognosis of MM.