Abstract 5521: Racial and ethnic disparities for intravascular large B-cell lymphoma: A Surveillance, Epidemiology, and End Results (SEER) database analysis with emphasis on Hispanics
Authors: Portillo Daniela Urueta , Rosas Daniel , Michalek Joel E. , Liu Qianqian , Diaz Duque Adolfo E. 
Published: June 2023

Background: Intravascular large b-cell lymphoma (IVLBCL) is a rare but highly aggressive subtype of non-Hodgkin lymphoma (NHL). IVLBCL is a clonal proliferation with selective growth within the blood vessel. It has been primarily described in Asian and European populations, and a median age presentation is in the sixth to seventh decades without a sex predilection. The US incidence is 0.95 in 1 million, but is thought to be higher, as the diagnosis is mainly done postmortem. Meanwhile, the incidence rate of IVBCL in Hispanics (HI) remained unknown. This study looks at demographics, treatment patterns, and outcomes of patients with IVLBCL in the US, examining disparities by HI vs Non-Hispanic (NH).

Methods: Data were analyzed on IVLBCL patients reported to the SEER 18 database between 2000 and 2018. SEER 18 contains the most comprehensive population-based cancer information in the US, covering approximately 27% of the US population and 36% of HI alone. The racial groups analyzed were NH whites, HI whites, blacks, and Asians/PIs (Pacific Islanders). Patient characteristics, age-adjusted incidence rate, and survival rate were compared across ethnic groups. Kaplan-Meier and Cox regression analyses compared overall survival (OS) between HI and NH. Multivariate analysis and propensity score matching were performed, with adjustment for age, stage and B-symptoms.

Results: We identified 164 patients with IVLBCL, of which 10% were HI. 41% of HI were male vs 44% of NH. HI were diagnosed at an older age, 72. vs 69 y.o., compared to NHI (p=0.907). Most of NH and HI were diagnosed between 60-80 y.o. (p=0.322), 53.1% and 47.1%, respectively. Regarding race, HI and NH were mainly identified as whites (88% vs 78%), followed by Asians (6% vs 17%) (p=0.013). For HI, 53% presented B symptoms compared to 16% of NH (p=&lt;0.001). On survival analysis, the survival probability at 2, 5 and 10 years of HI vs NH was (0.540 vs 0.505), (0.432 vs 0.425), and (0.443 vs 0.237), respectively. The median survival time was 0.8 years for HI and 1.9 years for NH. The 10 year OS probability was not significantly different for HI vs NH (p=0.66).On multivariate analysis, when adjusted for age, those patients who were 60 to 80 y.o. had worse OS compared to those younger than 60 y.o., with HR 1.4 (95% CI: 0.7 - 2.1).

Conclusion: In our study, despite a lower percentage of patients identified as Asian in our HI population, there is a significant difference in the presence of B-symptoms between HI and NH, going against the traditional description of an Asian variant with increased systemic symptoms. Despite this finding, it demonstrated similar outcomes in the 10 years survival analysis for HI and NH. Standardized treatment may explain why no variation was reported in OS. Our analysis shows that ethnic variations do not seem to affect oncological outcomes in IVLBCL for HI in the US.

Citation Format: Daniela Urueta Portillo, Daniel Rosas, Joel E. Michalek, Qianqian Liu, Adolfo E. Diaz Duque. Racial and ethnic disparities for intravascular large B-cell lymphoma: A Surveillance, Epidemiology, and End Results (SEER) database analysis with emphasis on Hispanics. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5521.