Relationship of pleural fluid pH and glucose: a multi-centre study of 2,971 cases.

BACKGROUND: Pleural fluid pH and glucose levels are both recommended in the workup of pleural effusions. Whether their levels correlate and predict each other or contribute independent knowledge is unclear. We aimed to investigate the pH/glucose relationship, assess their concordance and ascertain whether performing both tests provides additional information to performing either test alone. METHODS: The pH and glucose measurements from 2,971 pleural fluid samples, from three centers in Spain, UK and Australia, were categorized into Cancer (n=1,045), Infection (n=544), Tuberculosis (n=249) and Others (n=1,133) groups. The relationship between pH and glucose values and their concordance at clinically relevant cutoffs (pH 7.2 and glucose 3.3 mmol/L) were assessed. RESULTS: The mean pH of the cohort was 7.38 (SD 0.22) and median glucose 5.99 (range, 0.00-29.36) mmol/L. A regression model of the relationship between glucose (log-transformed) and pH with a restricted cubic spline showed linear (P<0.01) and nonlinear effects (P<0.01). The relationship was strong with a narrow confidence interval but the prediction interval was wide. Most (91.9%) samples were concordant using pH and glucose levels at cutoffs of 7.20 and 3.30 mmol/L respectively. Using pH alone, without glucose, captured 95.0% of the infection-related effusions with either pH or glucose below cutoff and glucose alone identified 91.7%. CONCLUSIONS: Pleural fluid pH and glucose have a strong non-linear relationship but, in most situations, the level of one cannot accurately predict the other. Concordance rates were high and either test is sufficient in the majority of cases.

Malignant pleural fluid from mesothelioma has potent biological activities.

BACKGROUND AND OBJECTIVE: Malignant pleural effusion (MPE) affects >90% of mesothelioma patients. Research on MPE has focused on its physical impact on breathlessness; MPE is rich in growth mediators but its contribution to tumour biology has not been investigated. We aimed to examine the potential effects of MPE in promoting growth, migration and chemo-resistance of mesothelioma. METHODS: Pleural fluid samples from 151 patients (56 mesothelioma, 60 metastatic pleural cancer and 35 benign) were used. Seven validated human mesothelioma cell lines and three primary cultured mesothelioma lines were employed. RESULTS: Pleural fluid from mesothelioma patients (diluted to 30%) consistently stimulated cell proliferation (trypan-blue cell viability assay) in five mesothelioma cell lines tested by (median) 2.23-fold over controls (all P < 0.0001). The fluid also induced cell migration by (median) 2.13-fold in six mesothelioma cell lines using scratch-wound assay. In a murine flank model of mesothelioma, tumour infused with daily instillations of pleural fluid grew significantly faster over saline controls (median 52.5 cm2 vs 28.0 cm2 at day 13, P = 0.028). Addition of MPE (diluted to 30%) to culture media significantly protected mesothelioma from cisplatin/pemetrexed-induced cell death in all three cell lines tested (median fold reduction of 1.29, 1.98 and 3.90, all P < 0.001 vs control). The growth effects of matched pleural fluid and cultured mesothelioma cells from the same patients did not differ significantly from unmatched pairs. CONCLUSION: This 'proof-of-concept' study reveals potent biological capabilities of malignant pleural fluid in mesothelioma pathobiology.

Asbestos in Asia.

Asbestos is a global killer. Despite lessons learned in the developed world on the use of asbestos and its hazardous pulmonary consequences, its use continues to increase in Asia. Although some countries such as Japan, Korea and Singapore have curtailed the use of this mineral, there are numerous countries in Asia that continue to mine, import and use this fibre, particularly China, which is one of the largest consumers in the world. Numerous factors ranging from political and economic to the lack of understanding of asbestos and the management of asbestos-related lung disease are keys to this observed trend. Awareness of these factors combined with early intervention may prevent the predicted Asian 'tsunami' of asbestos diseases.

Comparison of fibulin-3 and mesothelin as markers in malignant mesothelioma.

BACKGROUND: Pleural malignant mesothelioma (MM) is a deadly tumour predominantly associated with asbestos exposure. A reliable diagnostic and prognostic marker for MM will significantly enhance clinical care and is an area of intense research. Soluble mesothelin is the most studied and an FDA-approved biomarker for MM. A recent report showed promising results using fibulin-3 as a new diagnostic marker. The aim of this study was to compare the utility of fibulin-3 versus mesothelin, singly or in combination. METHODS: Fibulin-3 and soluble mesothelin were determined by ELISA in the plasma and pleural fluid of 153 patients presenting with a pleural effusion including 82 with MM, 36 with non-MM malignant effusions and 35 with benign effusions. Biomarker concentrations were determined in the plasma of an additional 49 cases with benign asbestos-related disease. RESULTS: Mesothelin provides better diagnostic accuracy than fibulin-3 for MM whether measured in plasma or pleural effusion: area under the curve (AUC) for plasma was 0.822 (95% CI 0.76 to 0.87) compared with 0.671 (0.61 to 0.73), respectively, and for pleural fluid AUC was 0.815 (0.74 to 0.87) compared with 0.588 (0.51 to 0.67), respectively. Effusion fibulin-3 was an independent significant prognostic factor for survival in MM patients; HR 2.08 (1.14 to 3.82), p=0.017. MM patients with effusion fibulin-3 levels below the median survived significantly longer than those with levels above the median (14.1 vs 7.9 months, p=0.012). Mesothelin and neutrophil to lymphocyte ratio were not significant prognostic markers. CONCLUSIONS: Soluble mesothelin is a superior diagnostic biomarker for MM compared with fibulin-3, whereas fibulin-3 provides superior prognostic information compared with mesothelin.