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

Our plain-English summary of Retrospective cohort study of survival length in malignant pleural effusion between 2015 and 2023, by C. Mounsey, N. Kanellakis, D. Addala, et al (BMJ Open Respiratory Research, 2025).

The study

• Authors: C. Mounsey, N. Kanellakis, D. Addala, W.M. Chew, I. Mechie, B. Iqbal, A. Elsheikh, A. Sundaralingam, R. Hallifax, N. Rahman
• Journal: BMJ Open Respiratory Research
• Published: 2025;12(1)
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.

© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.

In plain English

This retrospective cohort study asked whether people with malignant pleural effusion (cancer-related fluid around the lung) lived longer if diagnosed more recently. The authors reviewed records of 742 patients discussed at the Oxford University Hospitals pleural team meeting between July 2015 and October 2023. The study did not examine asbestos exposure. Lung cancer was the most common underlying cancer (28.8%), followed by mesothelioma (20.5%) and breast cancer (16.6%). Median survival after the effusion was diagnosed was 150 days. The patients were split into three equal groups by diagnosis date. Median survival was 157, 138 and 151 days, and the differences between groups were not significant. Year of diagnosis was not significantly linked to survival in regression analyses. The same was true for patients with lung cancer, mesothelioma or breast cancer, for fitter patients, and for those given anti-cancer drug treatment, even though use of that treatment rose over time. The number diagnosed on the Oxford Pleural Database rose 53.6%, from 69 in 2016 to 106 in 2022. The authors concluded that survival had remained stagnant. They listed the single-centre design and unmeasured confounders among the study's limitations.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Single-centre retrospective cohort study of medical records
• Who was studied: 742 patients with malignant pleural effusion (MPE) reviewed at the Oxford University Hospitals pleural multidisciplinary team meeting, July 2015 to October 2023. They were drawn from 781 identified, and 39 were excluded for missing data. Median age was 72. Underlying cancers were lung (28.8%), mesothelioma (20.5%, n=152) and breast (16.6%), among others.
• Exposure: Not an asbestos exposure study. The factor compared was the date of MPE diagnosis. Patients were grouped into three equal time periods (July 2015 to October 2018, October 2018 to April 2021, and April 2021 to October 2023), and individual year of diagnosis was also analysed.
• Main results:
  • Median overall survival from MPE diagnosis for all 742 patients was 150 days (IQR 55 to 473).
  • Median survival was 157, 138 and 151 days in time-period groups 1 to 3. Log-rank tests showed no significant differences.
  • Year of MPE diagnosis was not significantly associated with survival. In the univariable analysis the HR was 1.01 (95% CI 0.97 to 1.04), p=0.71. In the multivariable analysis adjusted for age, sex and LENT score (n=676), the HR was 1.01 (0.98 to 1.05), p=0.56.
  • The lack of survival improvement was consistent in four groups: patients with MPE from lung cancer, mesothelioma or breast cancer; patients with performance status 0 to 2; and patients who received systemic anti-cancer therapy.
  • Higher LENT or PROMISE scores and male sex were associated with poorer survival. In the multivariable model, the LENT score HR was 1.70 (1.60 to 1.81), and sex had an HR of 1.34 (1.14 to 1.58) with female as the reference.
  • The proportion of patients receiving systemic anti-cancer therapy rose in later diagnosis periods (any therapy: chi-squared 12.5, p=0.002).
  • On the Oxford Pleural Database, the number diagnosed with MPE rose 53.6%, from 69 in 2016 to 106 in 2022. Heart failure-related effusion or pleural infection showed no such increase (44 in 2016 compared with 39 in 2022).
• The authors' conclusion: The authors concluded that survival after developing symptomatic MPE has remained stagnant while its incidence is increasing. They suggested MPE may be a clinically distinct entity needing treatment specific to the pleural space.
• Limitations the authors state:
  • Single-centre design may limit generalisability to other healthcare settings.
  • Not all potential confounders were included in the Cox analyses, such as mutation status of the primary cancer and pleurodesis success.
  • Not all local MPE cases may have been included, for example patients with small asymptomatic effusions or palliative patients not referred.
  • The analysis of time from primary cancer diagnosis to MPE was limited by small numbers and wide variation.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Pleural Effusion, Performance Status, Lung Cancer, Mesothelioma.

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