Overall Survival Trends and Clinical Characteristics of Plasmacytoma in the United States: A National Cancer Database Analysis

Background: Given the rarity of plasmacytoma, large-scale database analysis can provide useful information regarding the clinical presentation and patient-related factors impacting overall survival (OS). Materials and Methods: The National Cancer Data Base was queried for patients with plasmacytoma between 2004 and 2013, excluding patients with systemic disease. Plasmacytomas were classified as originating in bone (P-bone), in extramedullary tissue (P-EM), or unspecified. Survival was estimated using the Kaplan-Meier and log-rank test method. We used Cox regression to determine specific outcomes adjusting for demographic, socioeconomic, geographic, facility type, year of diagnosis, and comorbid factors. Results: In total, 6225 patients were identified, of which 61.5% were men. The median age at diagnosis was 64 years (range, 18-90 years), and the median follow-up was 58 months. The primary site of disease was P-bone in 4056 (65.1%) patients and P-EM in 1468 (23.6%), and the remaining 701 patients were P-unspecified. The unadjusted median survival for solitary P-bone was 89 months (95% confidence interval, 82.9-95.0 months), and for solitary P-EM was 117.3 months (95% confidence interval, 108.8 months to not reached). Factors associated with improved OS include younger age, private insurance, higher income, solitary lesion, and lower comorbidity score. Patients with P-bone disease treated at academic facilities had improved OS. Only 65% of patients with solitary plasmacytoma lesions received radiation treatment. Age greater than 75 years and increased distance to treatment facility was associated with a decreased likelihood of receiving radiation. Conclusions: This is the largest study examining outcomes of patients with plasmacytoma using a large database analysis, revealing unique aspects of P-EM versus P-bone and underutilization of radiation treatment. This is the largest study examining outcomes of patients with plasmacytoma, using the National Cancer Data Base. Clinical and patient-related factors impacting overall survival were studied for both bone and extramedullary plasmacytoma. Patients with bone plasmacytoma who were treated at academic facilities had improved overall survival. Surprisingly, we found radiation treatment was underutilized in patients with solitary lesions, especially in those older than 75 years and with increasing distance from treatment facility.