To define the effectiveness of radiotherapy in the treatment of patients with extramedullary plasmacytoma of the head and neck (EMPHN).
We searched the Mayo Clinic Rochester Department of Radiation Oncology electronic Tumor Registry and identified 18 consecutive patients with a diagnosis of solitary EMPHN. Sixteen patients were treated with radiotherapy at initial diagnosis and 2 received salvage radiotherapy for local failure after surgery. Median dose administered was 50.4 Gy. Median follow-up was 6.8 years.
One patient (6%) developed a marginal recurrence 12 months after treatment. Six patients (33%) developed multiple myeloma (2 patients) or plasmacytomas at distant sites (4 patients) at a median of 3.1 years after diagnosis (range, 0.02 to 9.6 years). Median and 5- and 10-year overall survival rates from the date of diagnosis are 12.5 years, 88%, and 55%, respectively. Two patients (11%) developed a radiation-induced malignancy at 6.5 and 6.9 years after treatment.
Radiotherapy provides excellent local and regional tumor control and survival in patients with EMPHN. To the best of our knowledge, this is the first report of presumed radiation-induced malignancy in this patient population.