Radiotherapy for Solitary Bony or Extramedullary Plasmacytoma.

Background/Aim: This study aimed to determine the oncological outcomes associated with curative radiotherapy for solitary bony or extramedullary plasmacytomas by drawing on clinical data from a single tertiary center. This study aimed to provide a comprehensive understanding of the efficacy of radiotherapeutic interventions and delineate the patterns of disease recurrence. Patients and Methods: Eleven consecutive patients diagnosed with solitary bony or extramedullary plasmacytomas and treated between May 2007 and November 2023 were retrospectively screened. Different radiotherapy doses and fractionations were employed, and statistical analyses were performed to assess overall survival (OS) and disease-free survival (DFS). Results: Among the 11 patients (9 males and 2 females), primary tumors were located within the bone in seven patients, whereas extramedullary tumors were observed in four patients. The median prescribed radiation dose was 46 Gy. The 5-year OS and DFS were 83.3% and 28.9%, respectively. Progression to multiple myeloma occurred in four patients with primary bony plasmacytoma. Local control rate was 88.9%, and one patient experienced distant metastasis after 32 months. Bony plasmacytoma has a high tendency of leading to multiple myeloma rather than extramedullary plasmacytoma (5-year progression to multiple myeloma-free survival rate, 20.8% vs. 100%, p=0.08). Conclusion: Radiotherapy is effective for solitary plasmacytomas with favorable local control and high objective response rates. A comparison with the existing literature supports the role of radiotherapy in the management of these conditions. The differences in outcomes between bony and extramedullary plasmacytomas emphasize the need for personalized treatment approaches.