Management of extramedullary plasmacytoma: Role of radiotherapy and prognostic factor analysis in 55 patients

Abstract

To investigate potential prognostic factors affecting patient outcomes and to evaluate the optimal methods and effects of radiotherapy (RT) in the management of extramedullary plasmacytoma (EMP). Data from 55 patients with EMP between November 1999 and August 2015 were collected. The median age was 51 (range, 22–77) years. The median tumor size was 3.5 (range, 1.0–15.0) cm. The median applied dose was 50.0 (range, 30.0–70.0) Gy. Thirty-nine patients (70.9%) presented with disease in the head or neck region. Twelve patients received RT alone, 9 received surgery (S) alone, 3 received chemotherapy (CT) alone, and 3 patients did not receive any treatment. Combination therapies were applied in 28 patients. The median follow-up duration was 56 months. The 5-year local recurrence-free survival (LRFS), multiple myeloma-free survival (MMFS), progression-free survival (PFS) and overall survival (OS) rates were 79.8%, 78.6%, 65.2% and 76.0%, respectively. Univariate analysis revealed that RT was a favourable factor for all examined endpoints. Furthermore, head and neck EMPs were associated with superior LRFS, MMFS and PFS. Tumor size <4 cm was associated with superior MMFS, PFS and OS; serum M protein negativity was associated with superior MMFS and PFS; age ≥50 years and local recurrence were associated with poor MMFS. The dose ≥45 Gy group exhibited superior 5-year LRFS, MMFS and PFS rates (94.7%, 94.4%, 90.0%, respectively), while the corresponding values for the dose <45 Gy group were 62.5% (P=0.008), 53.3% (P=0.036) and 41.7% (P<0.001). Involved-site RT of at least 45 Gy should be considered for EMP. Furthermore, patients with head and neck EMP, tumor size <4 cm, age <50 years and serum M protein negativity had better outcomes.