Purpose: To analyze the outcomes of patients treated for solitary plasmacytoma with definitive radiotherapy (RT).
Material and Methods: Thirty-two patients with solitary plasmacytoma of bone (SPB; 22 patients) and extramedullary plasmacytoma (EMP; 10 patients) were treated between 1963 and 2006. The median RT dose was around 42.7 Gy (range, 15–54 Gy) over a median of 25 fractions (range, 1–32 fractions). No patient received adjuvant chemotherapy. Median follow-up was 10.1 years (range, 1–33 years). Median follow-up on living patients was 7.3 years (range, 2.1–33 years).
Results: The 10-year local-control rate after RT was 87%. All 4 patients who developed a local recurrence had SPBs ≥5 cm. The 10-year multiple myeloma-free survival rates were: SPB, 30%; EMP, 90%; and overall, 50%. Progression to multiple myeloma occurred at a median of 25.1 months after RT. The 10-year overall and cause-specific survival rates were 65% and 77%, respectively. The 10-year cause-specific survival rate was 65% for patients with SPB versus 100% for those with EMP (P = 0.006).
Conclusion: Moderate dose RT results in a high rate of local control. Patients with SPB are more likely to progress to multiple myeloma, which adversely affects their survival compared with those with EMP.
From the Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida.
The authors have no conflicts of interest to declare.
Reprints: William M. Mendenhall, MD, 2000 SW Archer Rd., PO Box 100385, Gainesville, FL 32610-0385. E-mail: firstname.lastname@example.org.