Background: Plasmablastic lymphoma (PBL) is a rare, aggressive subtype of large B-cell lymphoma with poor outcomes and limited population-level data available. Social determinants of health (SDOH)—such as race, income, and geography—are known to impact outcomes in several hematologic malignancies and may be relevant in PBL which has been prevalent in underrepresented patients (i.e. HIV +), the influence of these socioeconomic factors in the outcomes of this lymphoma are poorly characterized. We used a large national cancer registry to evaluate the influence of SDOH on the survival of PBL patients.

Methods: We conducted a retrospective cohort study using the SEER-17 database, identifying patients diagnosed with PBL (ICD-O-3 code 9735/3) from 2000 to 2022. Patients diagnosed at autopsy or by death certificate and those with missing survival data were excluded. Variables analyzed included sex, race/ethnicity, median household income, and metropolitan status. Outcomes assessed were overall survival (OS) and cancer-specific survival (CSS), analyzed using Kaplan–Meier curves and Cox proportional hazards models. Adjusted hazard ratios (HR) with 95% confidence intervals (CI) were generated for all comparisons. Analyses were performed using SPSS, with p < 0.05 considered statistically significant.

Results: A total of 891 patients met inclusion criteria; 77.7% were male, and 93.4% lived in metropolitan areas. Racial distribution was 76.4% White, 14.3% Black, and 8.1% other races. Median OS for the overall cohort was 18 months (95% CI, 12–24), and median CSS was 40 months (95% CI, 13.2–66.8).

In unadjusted analysis, race significantly impacted survival with median OS for White, Black and other patient's races of 21, 15 and 11 months, respectively (p = 0.029). On multivariable analysis, Black race remained independently associated with inferior OS (HR 1.38, 95% CI 1.07–1.77, p = 0.013); the association for other races trended toward significance (HR 1.36, 95% CI 0.99–1.88, p = 0.061). Black patients had a median CSS of 31 months compared to 50 months in White patients. Patients of other racial backgrounds had a median CSS of 22 months. However, these differences were not statistically significant (p = 0.252). On multivariable analysis, CSS was comparable across all racial backgrounds.

Income and geography were associated with survival in univariate analysis but not after adjustment. Patients with income <$60,000 had lower median OS (11 months) compared to those earning $60,000–90,000 or >$90,000 (both 21 months; p = 0.097). CSS was longest in the patients earning more than $90,000 (68 months), followed by those earning $60,000–90,000 (51 months) and those earning less than $60,000 (16 months). However, these differences were not statistically significant (p = 0.15). In adjusted analysis, income did not significantly predict OS or CSS. Patients residing in non-metropolitan areas had significantly worse OS (9 vs. 21 months, p = 0.042), though this association did not persist in multivariable models. Metropolitan residence was not linked to longer CSS (p = 0.052). Metropolitan residence did not significantly predict OS or CSS in the adjusted analysis.

Conclusion: In this large, population-based cohort, Black patients with PBL had significantly worse OS compared to White patients, even after adjustment for demographic and geographic factors. While trends toward inferior outcomes were observed in lower-income and rural populations, these did not reach statistical significance in adjusted models. These findings suggest racial disparities in PBL outcomes and underscore the need to further understand the cause of these differences and develop interventions to address existing potential inequities in rare aggressive lymphomas. Further research through larger registries and prospective cohorts will help to understand the role of SDOH as possible in PBL and rare NHL.

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2025
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