134P Clinical and epidemiological patterns of pleural mesothelioma in the United States: Long-term data from SEER database

Malignant pleural mesothelioma is a rare and aggressive cancer type with a rising global incidence over the past decade. In this study, we aimed to assess the clinical and epidemiological patterns of pleural mesothelioma in the United States. Moreover, we tracked the changing trend of overall survival and disease distribution of the different histological subtypes. We used Surveillance, Epidemiology, and End Results Program (SEER) database to extract data of cases diagnosed with microscopically confirmed malignant pleural mesothelioma between 2004 and 2019 [17 reg; Nov 2021 sub]. Cases with unknown/ unreported stage were excluded. We analyzed data from 9,511 malignant pleural mesothelioma patients. Most cases were males (77.6%, n = 7384), of white race (90.8%, n = 8635), ≥70 years at diagnosis (65.3%, n = 6215), and presented with distant disease (70.5%, n = 6703). The overall incidence rate of pleural mesothelioma was 7.2 per million and decreased from 7.7 per million in 2004 to 6.1 per million in 2019 with a marginal increase in the median overall survival (Table). Moreover, patients became more likely to present with localized and regional stages. Longitudinal tracking of cases with different histological subtypes showed an increase in the epithelioid mesothelioma which had a statistically significant longer median overall survival compared with fibrous mesothelioma and biphasic mesothelioma (12 months vs. 4 and 8 months, respectively; P = 0.001). The incidence of pleural mesothelioma decreased between 2004 and 2019 with a marginal improvement in the median overall survival. However, there is a substantial increase in the proportion of patients presenting with epithelioid mesothelioma and those presenting with localized stage.