Endostatin levels in exudative pleural effusions

Pleural biomarkers in diagnostics of malignant pleural effusion: a narrative review

Although cytology and pleural biopsy of pleural effusion (PE) are the gold standards for diagnosing malignant pleural effusion (MPE), these tools’ diagnostic accuracy is plagued by some limitations such as low sensitivity, considerable inter-observer variation and invasiveness. The assessment of PE biomarkers may hence be seen as an objective and non-invasive diagnostic alternative in MPE diagnostics. In this review, we summarize the characteristics and diagnostic accuracy of available PE biomarkers, including carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigens 125 (CA125), carbohydrate antigen 19-9 (CA19-9), carbohydrate antigen 15-3 (CA15-3), a fragment of cytokeratin 19 (CYFRA 21-1), chitinase-like proteins (CLPs), vascular endothelial growth factor (VEGF) and its soluble receptor, endostatin, calprotectin, cancer ratio, homocysteine, apolipoprotein E (Apo-E), B7 family members, matrix metalloproteinase (MMPs) and tissue-specific inhibitors of metalloproteinases (TIMPs), reactive oxygen species modulator 1 (Romo1), tumor-associated macrophages (TAMs) and monocytes, epigenetic markers (e.g., cell-free microRNA and mRNA). We summarized the evidence from systematic review and meta-analysis for traditional tumor markers’ diagnostic accuracy. According to the currently available evidence, we conclude that the traditional tumor markers have high specificity (around 0.90) but low sensitivity (around 0.50). The diagnostic accuracy of novel tumor markers needs to be validated by further studies. None of these tumor biomarkers would have sufficient diagnostic accuracy to confirm or exclude MPE when used alone. A multi-biomarker strategy, also encompassing the use of artificial intelligence algorithms, may be a valuable perspective for improving the diagnostic accuracy of MPE.

Prognostic values of VEGF and endostatin with malignant pleural effusions in patients with lung cancer

AIMS

Angiogenesis is important in malignant pleural effusion (MPE) formation and it is regulated by a number of pro- and anti-angiogenic cytokines. The purpose of this study was to evaluate the prognostic value of angiogenic factor vascular endothelial growth factor (VEGF) and angiogenesis inhibitor endostatin in lung cancer patients with MPE, and investigate the relationship between these two kinds of agent.

METHODS

Using enzyme-linked immunoadsorbent assay, the concentrations of VEGF and endostatin were measured in pleural effusions (PE) and serum from a total of 70 lung cancer patients with MPE and 20 patients with tuberculosis.

RESULTS

Compared to patients with tuberculosis, the levels of VEGF and endostatin in both PE and serum were significantly higher in patients with lung cancer. There were statistically significant correlations between VEGF levels in PE and serum (r=0.696, <0.001), endostatin levels in PE and serum (r=0.310, p=0.022), and VEGF and endostatin levels in PE (r=0.287, p=0.019). Cox multivariate analysis revealed that elevated pleural VEGF and endostatin levels and serum endostatin level were independent predictors of shorter overall survival.

CONCLUSION

Both pro- and anti-angiogenic factors are likely contributors to PE formation. Our results suggest that the levels of VEGF and endostatin in PE, together with endostatin in serum, may be potential prognostic parameters for lung cancer patients with MPE.

Diagnostic accuracy of endostatin for malignant pleural effusion: A clinical study and meta-analysis

BACKGROUND

The diagnosis of malignant pleural effusion (MPE) remains a clinical challenge. Many studies suggest that endostatin is a potential marker for MPE. This study aimed to determine the diagnostic value of endostatin with respect to MPE and to summarize the overall diagnostic performance of endostatin via a meta-analysis.

METHODS

Pleural effusion samples from patients with both malignant and nonmalignant disease were collected, and the pleural levels of endostatin and carcino-embryonic antigen (CEA) were subsequently measured. The diagnostic performances of endostatin and CEA were analyzed via standard receiver operator characteristic curve analysis methods, using the AUC as a measure of accuracy. The overall diagnostic accuracy of endostatin for MPE was summarized through a bivariate meta-analysis with standard method recommended.

RESULTS

Fifty-two patients with MPEs and 64 patients with benign pleural effusions (BPEs) were included this study. Pleural endostatin levels were significantly increased in the setting of MPE compared with BPE (104.78 ± 64.58 vs. 56.81 ± 28.84 ng/ml; p < 0.001). Using a cutoff value of 79.7 ng/ml, the sensitivity and specificity of endostatin in diagnosing MPE were shown to be 51.92% and 85.94%, respectively, and the AUC was 0.747. The combination of endostatin and CEA enhanced diagnostic performance with respect to MPE. In addition to this study, another eight studies were included in this meta-analysis. The pooled diagnostic estimates were 0.69 for sensitivity and 0.78 for specificity. The positive likelihood ratio and negative likelihood ratio for endostatin were 3.16 and 0.40, respectively. The diagnostic odds ratio was 7.89, and the AUC of the summary receiver operator characteristic curve was 0.79.

CONCLUSION

Pleural levels of endostatin are increased in the setting of MPE. However, endostatin exhibits a limited efficacy for the diagnosis of MPE and shows a relatively low sensitivity. The assessment of endostatin in combination with CEA may enhance diagnostic accuracy with respect to MPE.

Diagnostic and prognostic significance of lysophosphatidic acid in malignant pleural effusions

BACKGROUND

Lysophosphatidic acid (LPA) is an important extracellular signal transmitter and intracellular second messenger in body fluids. It can be detected in the ascitic fluid of patients with ovarian cancer. Increasing evidence shows that LPA can stimulate cancer cell proliferation and promote tumor invasion and metastasis. Our study aimed to evaluate the diagnostic value of LPA in differentiating between malignant pleural effusions (MPEs) and benign pleural effusions (BPEs) and to evaluate the association between the level of LPA in MPE and the prognosis of lung cancer patients.

PATIENTS AND METHODS

The level of LPA in the pleural effusions (PEs) of 123 patients (94 MPE, 29 BPE) with lung cancer was evaluated using an enzyme-linked immunosorbent assay. The performance of LPA was analyzed by standard Receiver operator characteristic curve (ROC) analysis methods, using the area under the curve (AUC) as a measure of accuracy. Overall survival (OS) curves and progression-free survival (PFS) curves were based on the Kaplan-Meier method, and the survival differences between subgroups were analyzed using the log-rank or Breslow test (SPSS software). A multivariate Cox proportional hazards model was used to assess whether LPA independently predicted lung cancer survival.

RESULTS

The levels of LPA differed significantly between MPE (22.08±8.72 µg/L) and BPE (14.61±5.12 µg/L) (P<0.05). Using a cutoff point of 18.93 µg/L, LPA had a sensitivity of 60% and a specificity of 83% to distinguish MPEs from BPEs with an AUC of 0.769±0.045 (SE) (P=0.000) (95% CI, 0.68-0.857). In the three pathological types of lung cancer patients with MPE, there were no significant associations between LPA levels and the length of PFS and OS (P=0.58 and 0.186, respectively). Interestingly, in the patients with MPE caused by lung adenocarcinoma there were significant associations between the LPA levels and the PFS and OS (P=0.018 and 0.026, respectively). Multivariate analysis showed that the LPA level was an independent prognostic factor for PFS in lung adenocarcinoma.

CONCLUSIONS

Our results indicate that LPA can be used as a new biomarker for the diagnosis of MPE caused by lung cancer and that higher levels of LPA are related to shorter PFS in adenocarcinoma of the lung.

Diagnostic molecular biomarkers for malignant pleural effusions

Malignant pleural effusions (MPEs) are a common and important cause of cancer-related mortality and morbidity. Prompt diagnosis using minimally invasive tests is important because the median survival after diagnosis is only 4–9 months. Pleural fluid cytology is pivotal to current MPE diagnostic algorithms but has limited sensitivity (30–60%). Consequently, many patients need to undergo invasive diagnostic tests such as thoracoscopic pleural biopsy. Recent genomic, transcriptomic, methylation and proteomic studies on cells within pleural effusions have identified novel molecular diagnostic biomarkers that demonstrate potential in complementing cytology in the diagnosis of MPEs. Several challenges will need to be addressed prior to the incorporation of these molecular tests into routine clinical diagnosis, including validation of molecular diagnostic markers in well-designed prospective, comparative and cost–effectiveness studies. Ultimately, minimally invasive diagnostic tests that can be performed quickly will enable clinicians to provide the most effective therapies for patients with MPEs in a timely fashion.

Transcription expression and clinical significance of vascular endothelial growth factor mRNA and endostatin mRNA in pleural effusions of patients with lung cancer

The aim of this study was to evaluate the individual and combined diagnostic utility of vascular endothelial growth factor (VEGF) mRNA and endostatin mRNA in pleural effusions of patients with lung cancer. Transcription levels of VEGF and endostatin were detected by reverse transcription polymerase chain reaction (RT-PCR) in pleural effusions of patients with lung cancer (92 cases) and with lung benign disease (36 cases). Both VEGF mRNA and endostatin mRNA was significantly higher in malignant, AC, and SCC effusions than in benign effusions (P < 0.01). In the subgrouping, VEGF mRNA was obviously higher than endostatin mRNA in malignant and AC effusions (P < 0.01), whereas VEGF mRNA and endostatin mRNA did not differ between AC group and SCC group (P > 0.05). In single, VEGF mRNA had the highest sensitivity (82.6%) and accuracy (84.3%), whereas endostatin mRNA had the highest specificity (100%). When combinations of VEGF mRNA and endostatin mRNA were evaluated together, they gave a high-diagnostic performance: sensitivity of 95.7% and accuracy of 93.8%, respectively. The detection of VEGF mRNA and endostatin mRNA appears to be suitable for distinguishing carcinoma cells from reactive mesothelial cells in pleural effusions, they could be useful to diagnose the pleural micrometastasis.

Advances in the investigation and treatment of pleural effusions

Pleural effusions present a challenge for both diagnosis and treatment. They are a commonly presenting problem of a wide range of local and systemic potentially life threatening diseases and cause significant breathlessness. Significant advances have been made in the last 5 years in the diagnostic pathway and management options. This article reviews recent developments in the investigation of pleural effusions, particularly in pleural fluid analysis, biomarkers, imaging and pleural biopsy, and in the treatment of pleural infection and both malignant and benign effusions, including the use of indwelling pleural catheters. Although significant recent advances have been made in the management of pleural effusions, there the need still remains for further research if we are to reduce the morbidity and mortality caused by pleural effusions.

Angiogenic factors and angiogenesis inhibitors in exudative pleural effusions

The angiogenesis system has been implicated in inflammatory and neoplastic processes; nevertheless, it has been little studied in relation to the pleural space. Our aim is to analyze pleural and plasma levels of the activators--vascular endothelial growth factor, basic fibroblastic growth factor, and inhibitors--endostatin and thrombospondin-1 and to estimate the association between these factors and related biochemical markers. We analyzed pleural fluid from 105 patients with one of the following types of pleural effusion: empyema or complicated parapneumonic, non-complicated parapneumonic, tuberculous, neoplastic and transudative. Angiogenesis activators were higher in exudates than in transudates (p < 0.001) and in empyema than in non-complicated parapneumonic patients (p < 0.001). Endostatin showed no significant differences. Trombospondin-1 showed higher levels in exudates than in transudates and in empyema than in non-complicated parapneumonic effusions (p < 0.001). In pleural exudates there was a positive correlation of angiogenesis activators and trombospondin-1 with low glucose and pH and high LDH. There was no correlation between pleural and plasma levels of the angiogenesis factors. We conclude that exudative pleural effusions showed higher vascular endothelial growth factor, basic-fibroblastic growth factor and trombospondin-1 values than transudative effusions that associated to low glucose and pH, and high LDH. There was no correlation between pleural and plasma concentrations, suggesting a compartmentalized response.