Solitary plasmacytoma is a rare disease whose treatment has not evolved much in the last decades. The role of radiotherapy in the curative treatment of this entity was defined in a major publication in the 1980s and has since been proven to be the best practice in several other comparative trials, mostly retrospective. The radiotherapy dose of curative intent has also been described over the same period and remains unchanged to this day. Thus, local control, disease cure rate, and rate and progression time for multiple myeloma have been unaffected for almost 30 years.