Primary mediastinal/thymic diffuse large B-cell lymphoma: a population-based study on incidence and survival

Primary mediastinal large B-cell lymphoma is a rare subtype of lymphoma. The contemporary incidence of primary mediastinal large B-cell lymphoma remains unknown, and a large population-based study has not been reported. It is essential to provide guidance for further strategies in reducing the disease burden via population-based preventive initiatives. This study aims to explore the epidemiology and effect of therapeutic advances on the survival of patients with primary mediastinal large B-cell lymphoma. This population-based study was conducted using the Surveillance, Epidemiology, and End Results Program (SEER), covering the period from 1975 to 2018. A total of 774 patients in the SEER 9 and 1654 patients in the SEER 18 were analyzed. The age-adjusted incidence rate of primary mediastinal large B-cell lymphoma increased from 0.05/1,000,000 in 1975 to 2.38/1,000,000 in 2018. A significant positive linear increase in the incidence trend was found in primary mediastinal large B-cell lymphoma, with an annual percent change of 8.47% (95% confidence interval 7.7-9.2%, P < 0.001, z test). The survival in primary mediastinal large B-cell lymphoma was significantly superior to nodal diffuse large B-cell lymphoma. The incidence of PMBCL increases over the year. The survival of patients with primary mediastinal large B-cell lymphoma has improved over time.