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Shaji K. Kumar, MD
Prashant Kapoor, MD, FACP
Shaji K. Kumar, MD
Prashant Kapoor, MD, FACP
Posted: Tuesday, November 8, 2022
Beatrice Fregonese, MPH, of Memorial Sloan Kettering Cancer Center, New York, and colleagues aimed to review the effectiveness of radiotherapy in locally controlling solitary bone and solitary extramedullary plasmacytomas and to explore factors that may predict progression to multiple myeloma. Presented during the 2022 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 2798), the results of this study indicate that definitive radiotherapy for these conditions may provide “excellent local control,” although progression to multiple myeloma is still common in patients with solitary bone plasmacytomas.
The investigators focused on 99 patients with solitary bone (n = 64) or solitary extramedullary (n = 35) plasmacytomas who had not experienced progression to multiple myeloma. Participant data were retrospectively reviewed for outcomes such as overall survival, local control, and progression to multiple myeloma.
Approximately 69% of patients with solitary extramedullary plasmacytomas and 84.4% of those with solitary bone plasmacytomas received a radiation dose of 45 Gy or higher. With a median time to a complete response of 7.7 and 15.46 months, 74% and 78% of individuals with extramedullary plasmacytomas and bone plasmacytomas achieved a complete response, respectively; three patients experienced in-field failure after a complete response. Of note, all participants who achieved a complete response were treated with a radiation dose of at least 40 Gy.
The 2-year overall survival for patients with solitary bone plasmacytomas was 98% and 68% for those with solitary extramedullary plasmacytomas (P = .004). Although 14 patients died, the cause of death in 5 patients with extramedullary plasmacytomas was not related to plasma cell neoplasms. The 2-year rate of progression to multiple myeloma was significantly higher among patients with solitary bone plasmacytomas than those with extramedullary plasmacytomas (P < .001). Of note, a univariate analysis revealed that individuals with bone plasmacytomas were at higher risk for progression to multiple myeloma than those with extramedullary plasmacytomas (P < .05).
Disclosure: Dr. Fregonese reported no conflicts of interest.
