Survival outcomes, clinical features and treatment patterns of solitary plasmacytoma in the United States: A National Cancer Database (NCDB) analysis of years 2004-2017.
Authors: Saba Ludovic , Fu Chieh Lin , Liang Hong , Dominguez Barbara , Greskovich John , Chaulagain Chakra Pani 
Published: June 2023

e20060 Background: Due to its rarity, comprehensive studies on plasmacytoma are limited. There are two main subtypes: solitary bone plasmacytoma (P-Bone) and extramedullary plasmacytoma (P-EM). In this IRB approved retrospective analysis, the NCDB was used to evaluate the clinical features and factors affecting the overall survival of patients with plasmacytoma who were treated at commission on cancer (CoC) accredited facilities across the USA. Methods: Using the NCDB, we identified N = 6,579 patients with plasmacytoma from 2004 to 2017, after excluding multiple myeloma patients. N = 4,816 patients had P-Bone & N = 1,763 patients had P-EM. Descriptive statistics were used and multivariable cox regression analysis was utilized to identify the independent survival factors, using significance level of p < 0.05. Kaplan-Meier curves were produced. SPSS was used to analyze the data. Results: P-Bone represented 73.2% of cases. Overall median survival time was 105 and 147 months for P-Bone and P-EM respectively; 56 and 149 months for < 37 Gy and ≥ 37 Gy radiation dose respectively; 66, 112, 107 and 132 months for no treatment, surgery alone, radiation therapy alone and combination therapy (surgery + radiation) respectively. Multivariable cox regression revealed that there were 10 significant independent survival factors including age, ethnicity, facility type, insurance status, median income, education level, Charlson-Deyo score, year of diagnosis, plasmacytoma site and treatment pattern. Patients with P-EM were less likely to die compared to P-Bone (HR = 0.734, p < 0.001). Hispanic patients were less likely to die compared to non-Hispanics (HR = 0.66, p < 0.001). In addition to that, patients with private insurance were less likely to suffer death compared to patients with no insurance (HR = 0.71, p = 0.01). Subjects who were treated in academic facilities were less likely to die compared to the ones who received care in non-academic centers (HR = 0.86, p < 0.001). Moreover, patients with median income ≥ $63,000 were less likely to die compared to patients with median income < $38,000 (HR = 0.85, p = 0.04). Subjects with higher level of education (no high school diploma in < 7%) were less likely to suffer death compared to subjects with lower level of education (no high school diploma in ≥ 21%) (HR = 0.82, p = 0.018). Patients who were treated with radiation alone (HR = 0.54, p < 0.001), surgery alone (HR = 0.57, p < 0.001), and combination therapy (HR = 0.43, p < 0.001) were less likely to die compared to patients who did not receive any treatment. Detailed analysis will be presented. Conclusions: In this largest real-world plasmacytoma cohort ever reported, we found that patients with P-Bone and those with lower socio-economic status had worse outcomes. In addition use of combination therapy and the use of a higher radiation dose ≥ 37 Gy were associated with better outcomes.