Radiation Therapy for Solitary Plasmacytoma and Multiple Myeloma: Guidelines From the International Lymphoma Radiation Oncology Group

Purpose To develop guidelines for the work-up and radiation therapy (RT) management of patients with plasma cell neoplasms. Methods and Materials A literature review was conducted covering staging, work-up, and RT management of plasma cell neoplasms. Guidelines were developed through consensus by an international panel of radiation oncologists with expertise in these diseases, from the International Lymphoma Radiation Oncology Group. RT volume definitions are based on the International Commission on Radiation Units and Measurements. Results Plasma cell neoplasms account for approximately one-fifth of mature B-cell neoplasms in the United States. The majority (∼95%) are diagnosed as multiple myeloma, in which there has been tremendous progress in systemic therapy approaches with novel drugs over the last 2 decades, resulting in improvements in disease control and survival. In contrast, a small proportion of patients with plasma cell neoplasms present with a localized plasmacytoma in the bone, or in extramedullary (extraosseous) soft tissues, and definitive RT is the standard treatment. RT provides long-term local control in the solitary bone plasmacytomas and is potentially curative in the extramedullary cases. This guideline reviews the diagnostic work-up, principles, and indications for RT, target volume definition, treatment planning, and follow-up procedures for solitary plasmacytoma. Specifically, detailed recommendations for RT volumes and dose/fractionation are provided, illustrated with specific case scenarios. The role of palliative RT in multiple myeloma is also discussed. Conclusions The International Lymphoma Radiation Oncology Group presents a standardized approach to the use and implementation of definitive RT in solitary plasmacytomas. The modern principles outlining the supportive role of palliative RT in multiple myeloma in an era of novel systemic therapies are also discussed.