Retrospective cohort study of survival length in malignant pleural effusion between 2015 and 2023

Malignant pleural effusion (MPE) is common, affecting approximately 15% of patients with cancer. Over recent years, there have been significant changes in both the diagnostic and therapeutic strategies for the condition, and recent epidemiological studies have shown improvements in survival across most major cancer types. However, it is currently unclear whether there has been an increase in survival in patients with MPE.

Medical records of patients diagnosed with MPE between 2015 and 2023 at Oxford University Hospitals were retrospectively reviewed. Patients were split into groups of equal size based on the date of MPE diagnosis and Kaplan-Meier survival analyses were performed. Subgroup analyses were conducted in patients with MPE by causative cancer type, performance status at diagnosis and treatment with systemic anti-cancer therapy. Cox regression analyses were carried out using the individual year of MPE diagnosis as an included variable.

742 patients with MPE were included. There was no improvement in survival length in patients managed in more recent years. This was consistent across effusions secondary to any primary malignancy; effusion secondary to lung cancer, mesothelioma or breast cancer; in patients with better performance status; and in patients who received systemic anti-cancer therapy.

Despite recent changes in the management of MPE and improving survival trends in cancer overall, survival time following the development of MPE appears to have remained stagnant over the 8-year time period under study. This suggests that MPE should potentially be considered as a discrete clinical entity, necessitating investigation of oncological therapies specifically targeted to the pleural space.