Prognostic impact of pleural effusion in patients with malignancy: A systematic review and meta-analysis

Our plain-English summary of Prognostic impact of pleural effusion in patients with malignancy: A systematic review and meta-analysis, by Y. Yang, J. Du, Y.S. Wang, et al (Clinical and Translational Science, 2022).

The study

• Authors: Y. Yang, J. Du, Y.S. Wang, H.Y. Kang, K. Zhai, H.Z. Shi
• Journal: Clinical and Translational Science
• Published: 2022;15(6):1340-1354
• Type of article: Meta-analysis, Systematic review
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The exact role of pleural effusion in the prognosis of cancer patients remains unclear. We aimed to systematically review the prognostic value of pleural effusion in patients with cancer. We performed a systematic review and meta-analysis with a systematic literature search. All cohort studies with available overall survival (OS) and progression-free survival (PFS) results for patients with cancer with or without pleural effusion were included. The Mantel-Haenszel method was used to calculate the pooled hazard ratios (HRs) and 95% confidence intervals (CIs). Heterogeneity and publication bias were examined. Subgroup analysis and sensitivity analysis were performed. A total of 47 studies with 146,117 patients were included in the analysis. For OS, pleural effusion was a prognostic factor associated with a poor prognosis for patients with cancer (HR, 1.58, 95% CI, 1.43-1.75; I2 94.8%). In the subgroup analysis, pleural effusion was a prognostic factor associated with poor survival for patients with lung cancer (HR, 1.44, 95% CI, 1.35-1.54; I2 60.8%), hematological cancer (HR, 2.79, 95% CI, 1.63-4.77; I2 29.4%) and other types of cancer (HR, 2.08, 95% CI, 1.43-3.01; I2 55.1%). For PFS, pleural effusion was a prognostic factor associated with a poor prognosis for patients with cancer (HR, 1.61, 95% CI, 1.28-2.03; I2 42.9%). We also observed that massive pleural effusion was a prognostic factor associated with a poorer prognosis compared to minimal pleural effusion. Pleural effusion had prognostic value in both OS and PFS of patients with cancer, except for patients with malignant pleural mesothelioma, regardless of whether the malignant effusion was confirmed histologically or cytologically. However, future evidence of other pleural effusion characteristics is still needed.

© 2022 The Authors. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.

In plain English

This article was a systematic review and meta-analysis, not a new study of patients. The authors searched five databases up to April 2, 2020 and pooled 47 cohort studies covering 146,117 patients with cancer. They asked whether fluid around the lungs (pleural effusion) was linked to survival. The article did not study asbestos exposure. Across 39 studies of overall survival, pleural effusion was associated with poorer survival (hazard ratio 1.58, 95% CI 1.43 to 1.75), with considerable variation between studies. The association held in lung cancer, blood cancers and other cancers. In three studies of malignant pleural mesothelioma, the pooled hazard ratio was 1.72 (95% CI 0.79 to 3.71), which was not statistically significant. The authors reported that effusion was not a prognostic factor in that group. In nine studies, effusion was associated with shorter progression-free survival (hazard ratio 1.61, 95% CI 1.28 to 2.03). Seven studies, which used different size cutoffs, linked massive effusions to poorer prognosis than minimal ones (hazard ratio 1.32, 95% CI 1.13 to 1.55). The authors noted possible publication bias. They did not examine comorbidities, medications or nutrition.

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: Systematic review and meta-analysis of published cohort studies, pooling hazard ratios with a random-effects model
• Who was studied: 47 published cohort studies covering 146,117 patients with any cancer type. The authors found them by searching five databases from their start to April 2, 2020. The included studies were published from 1990 to 2020 in many countries.
• Exposure: Not asbestos. The factor studied was pleural effusion compared with no effusion. Two further comparisons were massive versus minimal effusion and metachronous (later-appearing) versus synchronous effusion. The outcomes were overall survival and progression-free survival.
• Main results:
  • Across 39 studies of overall survival in patients with cancer, pleural effusion was associated with poorer survival: HR 1.58, 95% CI 1.43 to 1.75
  • The 39 overall-survival studies showed considerable heterogeneity (I2 = 94.8%)
  • By cancer type, the overall-survival hazard ratio was 1.44 (95% CI 1.35 to 1.54) for lung cancer and 2.79 (95% CI 1.63 to 4.77) for hematologic malignancy
  • For patients with malignant pleural mesothelioma (three studies), the pooled overall-survival HR was 1.72 (95% CI 0.79 to 3.71). The authors reported that pleural effusion was not a prognostic factor in this group.
  • The malignant pleural mesothelioma subgroup had considerable heterogeneity (I2 = 91.9%)
  • In the subgroup of studies where malignant effusion was confirmed cytologically or histologically, the overall-survival HR was 1.67 (95% CI 1.42 to 1.95)
  • Across nine studies, pleural effusion was associated with shorter progression-free survival: HR 1.61, 95% CI 1.28 to 2.03
  • Across seven studies, massive effusion was associated with poorer prognosis than minimal effusion: HR 1.32, 95% CI 1.13 to 1.55. The studies used different cutoffs (1 cm, 2 cm, or 200 ml).
  • Across three studies, metachronous effusion compared with synchronous effusion was not a prognostic indicator: HR 1.29, 95% CI 0.60 to 2.76
• The authors' conclusion: The authors concluded that pleural effusion had prognostic value and was associated with a poor prognosis for patients with cancer, except for those with malignant pleural mesothelioma. They said this held whether or not malignant effusion was confirmed histologically or cytologically.
• Limitations the authors state:
  • Possible publication bias, which the authors said may overestimate the effect of pleural effusion on prognosis
  • Because few studies were available, characteristics such as bilateral versus unilateral effusion and bloody versus non-bloody effusion were not examined
  • Comorbidities, medications and nutritional status, which can affect survival, were not addressed

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Systematic Review, Meta-Analysis, Prognosis, Overall Survival, Progression-Free Survival, Hazard Ratio, confidence interval.

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