Radiotherapy for Extramedullary Plasmacytoma of the Head and Neck

Purpose: To define the effectiveness of radiotherapy in the treatment of patients with extramedullary plasmacytoma of the head and neck (EMPHN).

Methods And Materials: 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.

Results: 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.

Conclusions: 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.