Incidence, Clinical Presentation and Outcome of Secondary Multiple Extramedullary Plasmacytomas: Experience at Roswell Park Cancer Institute.

Introduction: Extramedullary plasmacytomas are malignant plasma cell tumors that arise outside of the bone marrow. They occur either as solitary tumors with a cure rate of over 95% with radiation therapy alone; or they may present as manifestations of advanced metastatic multiple myeloma, referred to as secondary extramedullary plasmacytomas (SEP). SEP usually present as multiple tumors, primarily in the head and neck area and often after multiple relapses in MM patient. Although the etiology of multiple SEP remains unknown, they are reflective of clinically advanced disease that no longer relies on the bone marrow microenvironment. The incidence, clinical outcome and natural history of SEP are not clearly delineated in the literature. With the recent use of novel therapies (thalidomide, lenalidomide, bortezomib) resulting in prolonged survival we have noticed an increase incidence of patients relapsing with SEP at our institute. This observation prompted us to formally evaluate SEP to characterize the clinical pattern of presentation, clinical course and correlation with use of novel therapies of SEP.

Methods: This is a single institute retrospective review. All patients seen at our institute with the diagnosis of MM were evaluable. Data was queried since 1990, which included a total of 343 patients.

Results: To date 100 patients have been reviewed and among these, 20 patients (20%) were noted to have SEP. Characteristics of these patients are outlined in details in table (1). 14 patients (70%) remain alive. However, none achieved a complete remission after the diagnosis of SEP.

Conclusion: In this study, the overall incidence of SEP was 20% on the patients so far evaluated. Majority of SEP patients have received prior novel agents. Systemic treatments seem to be effective in controlling progression of SEP though achievement of CR status has not been possible with current therapeutic interventions. Our finding are intriguing as the incidence of SEM seems to be increasing, which may reflect either unveiling of the natural history of the disease through improved survival from the use of novel agents, or this may be reflective of a change in the biology of MM.

We intend to present the complete analysis of all cases at the meeting.