A National Cancer Database Analysis of Demographics, Treatment Patterns and Survival Trends of Patients with Plasmablastic Lymphoma in US: Does Ethnicity Predict Enhanced Outcomes?

Background: Plasmablastic lymphoma (PbL) is an exceedingly rare, aggressive non-Hodgkin lymphoma with overlapping features of myeloma and lymphoma diagnosed most commonly in immunocompromised individuals, especially in the setting of human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV) infection ( Int J Lab Hematol PMID 36074710). Pathologically, it is characterized by lacking CD20 and PAX5 expression with the presence of CD38, CD138, MUM1/IRF4, Blimp1, and XBP1 expression ( Blood Lymphat Cancer PMID 31360094). There is no established standard of care ( Blood PMID 25636338). Due to the disease's rarity, limited information is available on PbL, especially when focusing on underrepresented minorities. This study aims to describe the demographics, treatment patterns, and survival outcome differences in Hispanic (HI) versus non-Hispanic (NH) patients in the United States with PbL.

Methods: Data was analyzed on patients with PbL in the US reported to the NCDB between 2010 and 2019. Sociodemographic and treatment characteristics were compared between ethnic groups. Kaplan-Meier and Cox regression analyses were used to compare overall survival (OS) between HI and NH populations. Multivariate analysis and propensity score matching were performed with adjustment for age, stage, co-morbidity score, insurance status, type of facility and great circle distance.

Results: Between 2010 and 2019, 1624 patients were diagnosed with PbL with 16% identified as HI. HI were diagnosed at a younger median age of 48 years as compared to NH at 58 years. Diagnosis was made predominately in males (78%) with no statistical difference between HI and NH. Most HI and NH were white (92% and 74% in HI and NH, respectively) with increased racial diversity among NH. 17% of all patients identified as black with 1% HI and 21% NH. Regarding income, 32% HI had an income less than $38,000 versus 23% NH; whereas, 31% NH had an income greater than $63,000 versus 20% HI [p=0.017]. 38% HI had a Charlson-Deyo Comorbidity Index score ≥ 2 as compared to 27% NH [p<0.001]. Table 1 provides additional information on demographics. 45% of all patients had stage IV disease at the time of diagnosis. 86% of all patients received treatment with no statistical difference among HI and NH [p=0.246]. 67% of HI were treated at academic/research programs compared to 50% of NH [p=0.004]. The median distance between the patient's residence and treatment facility was 6.9 miles for HI versus 9.8 miles for NH [p=0.001].

The survival probability at 2, 5, and 10 years for HI was 59%, 52%, and 42%, respectively as compared to NH was 47%, 37%, and 31%, respectively. The median survival time (MS) was 9.4 years in HI versus 1.4 years in NH [p <0.001]. Figure 1 shows the Kaplan Meier curve comparing overall survival (OS) between HI versus NH.When adjusted on multivariate analysis, there were no independent variables associated with better or worse OS; moreover, propensity matched analysis showed no MS difference between HI vs NH (1.79 years versus 1.17 years).

Conclusion: This hospital-based analysis noted that HI presented with PbL at a younger age than NH; however, HI more frequently had a higher Charlson-Deyo Comorbidity Index score than NH. There was no statistical difference in the stage at diagnosis between HI and NH. Additionally, HI had a lower income and no medical insurance as compared to NH suggesting HI possibly had inferior access to medical resources. Paradoxically, HI had significantly higher OS rates. Further insight into the disease's intrinsic characteristics, as well as biological factors, is needed to gain a better understanding of these poor outcomes.