Multi-institutional analysis of solitary extramedullary plasmacytoma of the head and neck treated with curative radiotherapy.

Purpose: The purpose of this study was to elucidate the efficacy and optimal method of radiotherapy in the management of solitary extramedullary plasmacytoma occurring in the head and neck regions (EMPHN).

Methods And Materials: Sixty-seven patients (43 male and 24 female) diagnosed with EMPHN between 1983 and 2008 at 23 Japanese institutions were reviewed. The median patient age was 64 years (range, 12-83). The median dose administered was 50 Gy (range, 30-64 Gy). Survival data were calculated by the Kaplan-Meier method.

Results: The median follow-up duration was 63 months. Major tumor sites were nasal or paranasal cavities in 36 (54%) patients, oropharynx or nasopharynx in 16 (23%) patients, orbita in 6 (9%) patients, and larynx in 3 (5%) patients. The 5- and 10-year local control rates were 95% and 87%, whereas the 5- and 10-year disease-free survival rates were 56% and 54%, respectively. There were 5 (7.5%), 12 (18%), and 8 (12%) patients who experienced local failure, distant metastasis, and progression to multiple myeloma, respectively. In total, 18 patients died, including 10 (15%) patients who died due to complications from EMPHN. The 5- and 10-year overall survival (OS) rates were 73% and 56%, respectively. Radiotherapy combined with surgery was identified as the lone significant prognostic factor for OS (p = 0.04), whereas age, gender, radiation dose, tumor size, and chemotherapy were not predictive. No patient experienced any severe acute morbidity.

Conclusions: Radiotherapy was quite effective and safe for patients with EMPHN. Radiotherapy combined with surgery produced a better outcome according to survival rates. These findings require confirmation by further studies with larger numbers of patients with EMPHN.