Disparities in Radiation Therapy Utilization for Solitary Plasmacytoma of Bone: A Surveillance, Epidemiology, and End Results Database Analysis.

Background/Objectives: Solitary plasmacytoma of bone (SPB) results from abnormal proliferation of plasma cells and accounts for 2-5% of all plasmacytic malignancies. Radiation therapy is the standard of care in treating SPB due to its efficacy in controlling disease progression and optimizing patient survival. However, prior studies have highlighted disparities in radiation therapy receipt among various cancer types. In this study, we aim to investigate whether similar sociodemographic and clinical disparities exist in the treatment of SPB through use of the Surveillance, Epidemiology, and End Results (SEER) database. Methods: The SEER database was queried for biopsy-confirmed cases of SPB between 2000 and 2021 using the ICD-O-3 histology code 9731/3 and primary site codes C40.0-41.9. Chi-square tests, Fisher's exact tests, and multivariable logistic regression were completed using SPSS v29.0.2, with significance set to p < 0.05. Results: A total of 4139 patients were identified, of which 75.3% received treatment with radiation therapy. Multivariable analysis revealed that low-income patients making less than $74,999 annually (aOR 0.80, 95% CI 0.67-0.97), as well as those from non-Hispanic Asian/Pacific Islander (aOR 0.49, 95% CI 0.33-0.73) and Hispanic (aOR 0.77, 95% CI 0.60-0.98) racial and ethnic groups, were significantly less likely to receive radiation therapy. Conclusions: These findings reveal notable disparities in radiation therapy utilization for SPB patients based on income and race and ethnicity, emphasizing the need for interventions to address systemic inequities, improve access to care, and ensure that all patients receive high-quality cancer care to optimize long-term outcomes.