Role of radiotherapy in solitary bone plasmacytomas

• Published in: Asia-Pacific journal of clinical oncology Vol. 1; no. 1; pp. 35 - 40
• Main Authors: CHAO, Michael W, GIBBS, Peter, NORRIS, Pam, PRINCE, Miles, KIFFER, John, FEIGEN, Malcolm, QUONG, George, WIRTH, Andrew, LIEW, Kuen-Hoe
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Science Pty 01.03.2005
• Subjects: local control; multiple myeloma; radiation therapy; solitary bone plasmacytoma
• ISSN: 1743-7555; 1743-7563
• DOI: 10.1111/j.1743-7563.2005.00003.x

Background:  Solitary bone plasmacytoma (SBP) is a rare tumor for which the standard treatment remains local radiotherapy (RT). While this results in high rates of local control, the majority of patients ultimately develop multiple myeloma (MM). Here we present a 20‐year multi‐institutional review of our experience in an attempt to better understand the natural history of SBP and to identify possible prognostic factors. Methods:  A total of 44 patients were identified. The inclusion criteria were the presence of a solitary bone lesion with histologic confirmation of plasma cells on biopsy, a normal bone marrow aspiration and trephine (<10% plasma cells), a negative radiographic skeletal survey, and no anemia, hypercalcemia or renal impairment secondary to plasma cell dyscrasia. Patient ages ranged from 25 to 83 years (median of 54 years) and 64% of patients had a monoclonal paraprotein in the serum and/or urine. All patients received local megavoltage RT with doses ranging from 30 to 54 Gy. Potential prognostic factors including age, gender, site of involvement, presence or absence of soft tissue extension, presence or absence of monoclonal paraprotein at diagnosis, persistence or disappearance of monoclonal paraprotein following RT, the time taken for monoclonal paraprotein to disappear following RT, and the use of magnetic resonance imaging (MRI) staging were evaluated to determine their impact on the likelihood of developing MM. Results:  Median follow up was 6 years (range 0.1–15.2 years). Effective local control was achieved in 42 (95%) patients, but 30 (68%) patients subsequently progressed to MM at a median time to progression of 1.6 years. The median survival from initial diagnosis was 7.5 years. We were unable to define any prognostic factors that were associated with an increased risk of developing MM. Conclusion:  Our series confirms the excellent local control achievable with RT. However, the majority of patients with SBP will ultimately progress to MM and strategies, such as adjuvant chemotherapy, should be explored in selected patients.