Clinical Characteristics And Prognosis Of Multiple Myeloma With Bone-related Extramedullary Disease At Diagnosis

Objective: Multiple myeloma(MM)is a malignancy of terminally differentiated monoclonal B cells,which is characterized by the presentation of malignant plasma cells within the bone marrow and the secretion of monoclonal immunoglobulin.Normally the tumor is localized in bone marrow.A minority of patients suffered from focal plasmacytoma without the typical end organ damage,and some patients developed extramedullary plasmacytoma during therapy either connected to primary bone lesion or far away from bone,which is defined as extramedullary disease(EMD).Clinically two types of extramedullary lesions can be described: a)tumor mass adjacent to bone and extending into soft tissue,b)soft tissue or visceral tumor that is not connected to the bone.It is reported that EMD is frequently associated with poor outcome and resistance to treatment.With increasing awareness of this malignancy,some practitioners and researchers adopted a strict definition of EMD-soft tissue EMD/strict EMD(s EMD),with plasmacytomas deriving from hematogenous spread.Dose b EMD features extramedullary invasion? To illuminate the problem,we performed a comparison on clinical and laboratory features and outcomes between patients with and without EMD to investigate whether or not patients suffering b EMD share the common clinical characteristics and outcome with patients without EMD.Methods: Patients diagnosed with MM were retrospectively reviewed at the Tianjin Medical University Cancer Institute and Hosiptal from January 2000 to December2015.Patients who were lost to follow-up and lack of indispensable medical documents were excluded.All of the patients had symptomatic myeloma(myeloma with end organ damage)requiring treatment.114 patients were finally analyzed.Thirty-six patients suffering b EMD at diagnosis were in comparison with 78 patients without EMD in clinical and laboratory characteristics and outcome.The clinical characteristics,laboratory parameters,responses,prognostic factors and outcomes were respectively analyzed.Statistical analysis was performed using SPSS 17.0(SPSS Inc.,Chicago,IL,USA),and statistical significance was considered to be P<0.05.The two groups were compared by the Chi-square test and T test.We calculated the OS from the date of diagnosis to the date of death from any cause,and surviving patients were censored at the final follow-up.PFS was measured as extending from diagnosis to disease progression or death(regardless of cause),whichever occurred first.The curves of OS and PFS were computed using the Kaplan-Meier method,and statistical differences between the curves were assessed by the log-rank test.Multivariate analysis was performed using the Cox proportional hazards regression model.Results: The clinical features,overall survival(OS)and progression free survival(PFS)between patients without b EMD and with b EMD showed no statistical significance.b EMD mostly occurs near the rib(46.1%)and verebrae(17.9%).Patients with diffuse bone lesion had worse prognosis than ones with focal lesion(P<0.05).PET/CT showed superior potential than X-ray(P=0.034)in detecting focal bone lesions.Patients treated with zoledronic acid had improved OS compared with patients with pamidronic acid(P=0.032).The group with interval ?7 months retained a worse OS(P=0.032)than interval < 7 months.Autologous Stem Cell Transplantation(ASCT)prolong patients' OS and PFS for both with and without b EMD.CR,?2-MG,UA and response were independent prognostic factors for survival in patients without b EMD and abnormal ALB and ADA played a significant role indicating shorter survival in patients with b EMD.Conclusion: The study reveals that b EMD should be equally treated with MM without EMD.Benefit from its anti-tumor value,a combination regimen containing zoledronic acid should be utilized from the very beginning.ASCT should be used in suitable patients for its ability to prolong patients' OS and PFS in both patients with and without b EMD.Since the delayed diagnoses and treatments contributed a worse prognosis,timely and proper management which leads to prolonged outcome should be underlined in clinical practice.The survey illustrates that there are prognostic differences between patients with and without b EMD which indicates that individualized strategy applying to various groups.