Introduction Primary mediastinal B cell lymphoma (PMBCL) is a rare subtype of large Bcell lymphoma. It accounts for approximately 5-10% cases of large B cell lymphoma.It is thought to arise from B cells in the thymus, usually involves the anterior-superiormediastinum and also tends to infiltrate the adjacent thoracic structures. First line treatment regimens include DA-EPOCH-R or R-CHOP (anti CD-20/Rituximab based). The purpose of thisstudy is to analyse survival trends and determine prevalence disparities inPMBCL.

Method We extracted cases of primary mediastinal B cell lymphoma, using the ICD Code 9679/3, from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2024 Sub (2000-2022). The data was stratified based on age, gender, race, year of diagnosis, median household income inflation adjusted to 2023, and the treatment modalities used. Survival curves were compared using Log-Rank test (GraphPad Prism).

Results Total 1460 cases of primary mediastinal B cell lymphoma were found from 2000 to 2022 in the SEER database. Of these cases, 61.6% were females and 38.4% were males. Median age at diagnosis was 35 years. Racial distribution in descending order was noted as: White patients (60%) followed by Hispanics (16.8%), Asians/Pacific Islanders (12.2%), and Black (9.1%), unknown race (1.4%), and Alaskans or Native Americans were less than 1%.

The 1-year OS of 94.5% (CI 95%, 93.2-95.6), 3-year OS of 88.2% (CI 95%, 86.2-89.8), and 5-year OS of 86.9% (CI 95%, 84.8-88.6).

Mortality-to-Incidence Ratio (MIR) trend revealed a progressive decline in mortality, notable for 2000-2005 (25.7%), 2006-2011 (21.7%), 2012-2016 (12.9%), and 2017-2022 (7.1%) (p <0.0001, Logrank test for trend).

Survival analysis was significant for higher MoS for age group 0-50 years compared to 50+ years of age (p <0.0001). Comparison of curves based on race showed highest MoS in Hispanics, followed by White, Asian/Pacific Islanders, Black, and lowest MoS in American Indians/Alaskan natives (p 0.0138). Similarly, chemotherapy-based treatment was associated with higher survival vs no chemotherapy (p <0.0001). Survival analyses based on gender, income and radiation-based management were statistically insignificant.

Conclusions Primary mediastinal B cell lymphoma is a rare malignancy with only 1460 cases reported in the past two decades in the SEER database. This neoplasm had a strong predilection for female gender and Caucasians race. Overall, better survival outcomes were associated with younger age, Hispanic origin, and management involving chemotherapy. Prognosis was independent of gender, income and treatment with radiotherapy. Our analysis also highlighted a down trending 6-yearly MIR from 2000 to 2022, likely attributed to newer treatment with targeted therapies leading to improved survival. Further research is warranted to determine the impact of next generation sequencing based immunotherapy on the survival outcomes.

This content is only available as a PDF.
2025
Sign in via your Institution