Pleural Fluid LDH Levels Linked to Shorter Survival in Lung Cancer Patients

Patients with lung cancer whose pleural effusion contains high levels of lactate dehydrogenase tend to survive for a shorter time, according to a retrospective cohort study conducted at a single Chinese hospital and published in BMC Pulmonary Medicine.

Researchers analyzed the clinical records of lung cancer patients diagnosed with malignant pleural effusion at The First Affiliated Hospital of Guilin Medical University between December 1, 2017, and December 31, 2019.

The study included 71 patients, whose median survival time was 10 months. The researchers set out to explore whether lactate dehydrogenase, or LDH, measured in the pleural fluid itself could serve as a prognostic marker for these patients, and to build a nomogram, a graphical prediction tool, to estimate survival.

In the initial univariate analysis, several factors were associated with shorter overall survival: a neutrophil-to-lymphocyte ratio of 3.55 or higher, a pleural fluid LDH level of 292 U/L or higher, not receiving chemotherapy, and not receiving targeted therapy. All of these associations reached statistical significance at the P < 0.05 level.

When the investigators moved to multivariable Cox analysis, which adjusts for multiple factors simultaneously, two variables remained independently associated with survival. Receipt of targeted therapy was linked to a lower hazard of death, with a hazard ratio of 0.503 and a 95 percent confidence interval of 0.274 to 0.925. In contrast, a pleural fluid LDH level of 292 U/L or higher was associated with a higher hazard of death, with a hazard ratio of 2.449 and a 95 percent confidence interval of 1.238 to 4.843.

Using the independent predictors identified in the Cox model, the team constructed a nomogram intended to predict survival in this patient group. The model’s discrimination was assessed with the Concordance Index, which came out at 0.703, and its calibration and performance were evaluated with calibration plots and decision curves, which the authors describe as revealing moderate discrimination.

The authors are careful to flag important limitations. They note that the observed association with treatment may be affected by residual confounding, meaning that unmeasured differences between patient groups could influence the results. They also emphasize that the internally validated two-variable model is exploratory and requires external validation before it can be used in clinical practice.

Because the study is retrospective and based on a small cohort of 71 patients from a single center, its findings should be viewed as hypothesis-generating rather than definitive. The reported association between higher pleural fluid LDH and shorter overall survival adds to the search for bedside markers that might help clinicians discuss prognosis with patients who have malignant pleural effusion, but the nomogram built from it remains a research tool pending validation in independent populations.

Subject of Research: The association between pleural fluid lactate dehydrogenase levels and survival in lung cancer patients with malignant pleural effusion.

Article Title: Higher pleural fluid lactate dehydrogenase is associated with shorter overall survival in lung cancer patients with malignant pleural effusion: a retrospective cohort study

Article References: Du, H., Zheng, S., & Luo, M. (2026). Higher pleural fluid lactate dehydrogenase is associated with shorter overall survival in lung cancer patients with malignant pleural effusion: a retrospective cohort study. BMC Pulmonary Medicine. https://doi.org/10.1186/s12890-026-04901-z

Image Credits: AI Generated

DOI: 10.1186/s12890-026-04901-z

Keywords: lung cancer, malignant pleural effusion, lactate dehydrogenase, prognosis, nomogram, retrospective cohort study, overall survival, BMC Pulmonary Medicine, Cox regression, biomarker, Higher, pleural