Pleural mesothelioma

Diagnostic value of biopsy sampling in predicting histology in patients with diffuse malignant pleural mesothelioma

BACKGROUND

The classification of diffuse malignant mesothelioma into epithelioid, biphasic, and sarcomatoid types is based on histologic patterns. The diagnosis is made on biopsies, and because of intratumoral heterogeneity, they may not be representative of the entire tumor. The number and volume of biopsies needed to reach diagnostic accuracy in diffuse malignant mesothelioma and their prognostic value remain unclear.

METHODS

This study examined 759 consecutive patients with pleural diffuse malignant mesothelioma treated by pleurectomy/decortication or extrapleural pneumonectomy for the presence of epithelioid and/or sarcomatoid histology and classified both the presurgery biopsies (core-needle or thoracoscopic) and surgical resection specimens. The number and volume of biopsies were correlated with pre- and postsurgery histologies and overall survival.

RESULTS

Diffuse malignant mesothelioma was classified as epithelioid (76%), biphasic (18%), sarcomatoid (5%), or indeterminate (1%) in biopsies and as epithelioid (64%), biphasic (32%), and sarcomatoid (4%) in surgical resection specimens (overall concordance, 80.6%). The positive likelihood ratios were 2.4, 13.6, and 90.1 for biopsies with epithelioid, biphasic, and sarcomatoid histologies, respectively. Concordant histologies between biopsies and resections were associated with a higher number of biopsies (median tissue blocks for concordant histologies vs discordant histologies, 3 vs 2; P < .002) but were less associated with a higher volume (median, 1.2 vs 1.1 cm3 ; P = .06). In a multivariate analysis, overall survival was independently predicted by histology in the resection specimen (P < .0001) but not in the biopsy (P = .09).

CONCLUSIONS

In contrast to epithelioid histology, sarcomatoid histology in biopsies is highly accurate. Despite intratumoral heterogeneity, the accuracy of histologic classification increases with the number of tissue blocks examined, emphasizing the diagnostic value of extensive sampling by presurgery biopsies.

Complement Protein C1q Binds to Hyaluronic Acid in the Malignant Pleural Mesothelioma Microenvironment and Promotes Tumor Growth

C1q is the first recognition subcomponent of the complement classical pathway, which acts toward the clearance of pathogens and apoptotic cells. C1q is also known to modulate a range of functions of immune and non-immune cells, and has been shown to be involved in placental development and sensorial synaptic pruning. We have recently shown that C1q can promote tumor by encouraging their adhesion, migration, and proliferation in addition to angiogenesis and metastasis. In this study, we have examined the role of human C1q in the microenvironment of malignant pleural mesothelioma (MPM), a rare form of cancer commonly associated with exposure to asbestos. We found that C1q was highly expressed in all MPM histotypes, particularly in epithelioid rather than in sarcomatoid histotype. C1q avidly bound high and low molecular weight hyaluronic acid (HA) via its globular domain. C1q bound to HA was able to induce adhesion and proliferation of mesothelioma cells (MES) via enhancement of ERK1/2, SAPK/JNK, and p38 phosphorylation; however, it did not activate the complement cascade. Consistent with the modular organization of the globular domain, we demonstrated that C1q may bind to HA through ghA module, whereas it may interact with human MES through the ghC. In conclusion, C1q highly expressed in MPM binds to HA and enhances the tumor growth promoting cell adhesion and proliferation. These data can help develop novel diagnostic markers and molecular targets for MPM.

State-of-the-art: Radiological investigation of pleural disease

Pleural disease is common. Radiological investigation of pleural effusion, thickening, masses, and pneumothorax is key in diagnosing and determining management. Conventional chest radiograph (CXR) remains as the initial investigation of choice for patients with suspected pleural disease. When abnormalities are detected, thoracic ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) can each play important roles in further investigation, but appropriate modality selection is critical. US adds significant value in the identification of pleural fluid and pleural nodularity, guiding pleural procedures and, increasingly, as "point of care" assessment for pneumothorax, but is highly operator dependent. CT scan is the modality of choice for further assessment of pleural disease: Characterising pleural thickening, some pleural effusions and demonstration of homogeneity of pleural masses and areas of fatty attenuation or calcification. MRI has specific utility for soft tissue abnormalities and may have a role for younger patients requiring follow-up serial imaging. MRI and PET/CT may provide additional information in malignant pleural disease regarding prognosis and response to therapy. This article summarises existing techniques, highlighting the benefits and applications of these different imaging modalities and provides an up to date review of the evidence.

Modern management of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a deadly disease that produces a significant worldwide health care burden. The majority of cases are associated with prior asbestos exposure, but recent studies have identified a possible genetic predisposition in a minority of patients. Historically, obtaining a pathologic diagnosis of MPM was challenging, but with current pathological techniques, a secure diagnosis is possible in the majority of patients. Curative therapy for MPM remains elusive, and the primary treatment option for fit patients is platinum-based chemotherapy. Encouraging recent reports suggest that there may be a benefit to the addition of bevacizumab to standard chemotherapy as well as with the use of immune checkpoint inhibitors in MPM. Selected patients may be considered for aggressive surgical approaches, but there is considerable controversy regarding the true benefit of surgery and multimodality therapy in this disease.

Malignant pleural mesothelioma signs and symptoms

Malignant pleural mesothelioma (MPM) is developed from mesothelial cells and its behavior depends on the degree of pleural invasion and adjacent organs. This extension around the pleural cavity or more unlikely located on a limited area leads to clinical signs as dyspnea, shortness of breath, cough or chest pain. The relationship between asbestos exposure and MPM has been well established. The symptoms of MPM usually appear 30–40 years after exposure to asbestos. Consequently, patients are unaware that the clinical presentation is related to their clinical exposure which happened much earlier in their lives. Clinical manifestations of MPM are usually nonspecific and should not be used alone as diagnostic criteria, even in case of previous asbestos exposure as recommended by the ERS guidelines.

Pleural fluid cytological yield and visceral pleural invasion in patients with epithelioid malignant pleural mesothelioma

INTRODUCTION

Malignant pleural mesothelioma (MPM) is an aggressive malignancy arising from mesothelial cells lining the pleura. Most commonly, it presents as a unilateral pleural effusion. MPM usually develops on the parietal pleural surface and later spreads to the visceral pleura. Visceral pleural involvement entails a more advanced disease stage and is therefore an important prognostic factor. Pleural fluid (PF) cytology is often the first diagnostic test, but the sensitivity in the literature varies from 4 to 77%. However, no data are available for the diagnostic yield of cytological PF analysis with regard to the visceral pleural involvement. The aim of this study is to assess whether PF cytological yield is related to the extent and pattern of visceral pleural invasion, as assessed by thoracoscopy.

METHODS

Medical records of all patients who underwent thoracoscopy for suspicion of malignant pleural effusion from two hospitals were reviewed. Patients were selected if they initially underwent a diagnostic thoracentesis before thoracoscopy, if visceral pleural appearance during thoracoscopy was clearly documented, and MPM confirmed on pleural tissue biopsy.

RESULTS

Seventy-five patients were selected. Forty-five patients had a positive PF cytology on thoracentesis, while 30 had a negative PF cytology. Thoracoscopy showed parietal pleural invasion in all subjects. Interestingly, 82% of patients with positive PF cytology on thoracentesis had visceral pleural involvement, whereas only 30% of those with negative PF cytology had visceral pleural invasion. The pattern of visceral pleural invasion consisted of pleural masses, nodules, or pleural thickening. A multivariate regression identified visceral pleural invasion (p < 0.001) as the only independent factor predicting the positivity of cytology on pleural effusion.

CONCLUSION

In epithelioid MPM, PF cytological yield was significantly higher in patients with visceral pleural invasion assessed by thoracoscopy. Positive PF cytology is associated with a more advanced disease.

Accuracy of pleural biopsy using thoracoscopy for the diagnosis of histologic subtype in patients with malignant pleural mesothelioma

BACKGROUND

Promising results with trimodality therapy combining surgery, chemotherapy, and radiotherapy have been obtained in the management of patients with malignant pleural mesothelioma (MPM). However, the histologic subtype has to be taken into account because of its influence on prognosis. The aim of the current study was to analyze retrospectively the accuracy, sensitivity, and specificity of preoperative thoracoscopy for diagnosis of the histologic subtype of MPM.

METHODS

The histologic reports from all consecutive patients undergoing 'intent-to-treat' surgery from 3 institutions as well as the initial pathologic diagnosis obtained using thoracoscopy were reviewed and compared after institutional review board approval. All cases of MPM were confirmed by a panel of pathologists.

RESULTS

Ninety-five patients were included in the current study. Of these 95 patients, 75 underwent extrapleural pneumonectomy, 9 patients underwent pleurectomy/decortication, and 11 patients underwent pleurectomy. Of the 95 patients with a final diagnosis of MPM, 80 (84.2%) were classified as having epithelial and 15 (15.8%) as having biphasic subtype. Among the 87 patients classified as having MPM of epithelial subtype after the initial thoracoscopy, 75 cases (86.2%) were confirmed to be a true histologic diagnosis and 12 cases (13.8%) were found to be of biphasic subtype at final diagnosis. One patient with a biphasic subtype at initial thoracoscopy was found to have MPM of epithelial subtype after surgery. The sensitivity and specificity values of an epithelial subtype diagnosis after thoracoscopy were 94% and 20%, respectively, with a positive predictive value of 86% and a negative predictive value of 37%. Conversely, the sensitivity and specificity values of a biphasic subtype diagnosis after thoracoscopy were 20% and 98%, respectively, with a positive predictive value of 75% and a negative predictive value of 87%.

CONCLUSIONS

Pleural biopsy performed using thoracoscopy is considered to be the cornerstone of the diagnosis and pleural staging of MPM. However, this procedure appears to be less efficient in diagnosing the histologic subtype as either epithelial or biphasic.

Management of Malignant Pleural Mesothelioma

Malignant mesothelioma is increasing in incidence globally and has no known cure. Its unique clinical feature of local infiltration along tissue planes makes it a difficult neoplasm to manage. There have been few randomized controlled trials regarding treatment options, although these have increased in recent years, and results are eagerly awaited. This article summarizes important advances in the management of mesothelioma, especially diagnostic and therapeutic aspects.

Quantitative evaluation of the apoptosis regulating genes Survivin, Bcl-2 and Bax in inflammatory and malignant pleural lesions

AIM

We aimed to identify defects in the programmed cell death pathway that can be related to pleural malignant mesothelioma (MM) unresponsiveness to chemotherapy.

MATERIALS AND METHODS

We quantified mRNA levels of the apoptosis regulating genes Survivin, member of the IAP family, Bcl-2 and Bax, members of the Bcl-2 family. We studied 22 non-neoplastic pleural samples, comprising normal and inflammatory tissue specimens, and 42 pleural MMs using real-time RT-PCR.

RESULTS

Very low mRNA levels of each apoptotic gene were detected in all normal pleural samples. All three genes displayed increased mRNA levels in inflammatory and tumor specimens. Survivin levels in pleuritis and MMs were significantly increased (333% and 908%, respectively) compared to normal counterparts (p=0.0147 and 0.00349, respectively). Bcl-2 and Bax levels were increased in inflammatory pleural samples (394%, p=0.001 and 188%, p=ns, respectively) and in MMs (94%, p=ns and 88%, p=0.0163, respectively). The Bcl-2/Bax ratio was higher in pleuritis than in MMs, compared to normal pleurae (441%, p=ns and 22%, p=ns, respectively); the difference between Bcl-2/Bax ratio in inflammatory and neoplastic pleural samples was significant (p=0.00375).

CONCLUSIONS

These results suggest that apoptotic defects in pleural MMs are linked to increased levels of Survivin, whereas variations in Bcl-2 and Bax expression appear less significant, although further studies are needed to highlight Bcl-2 family members interactions in apoptosis control. Survivin progressive accumulation from normal pleura to MM suggests this gene may be important in mesothelial cancerogenesis. Survivin overexpression may also be involved in pleural MM resistance to oncological therapies. Therefore, Survivin may represent a promising novel target for selective therapies.

Vascular endothelial growth factor is an autocrine growth factor in human malignant mesothelioma

Vascular endothelial growth factor (VEGF), a potent mitogen for vascular endothelium, is expressed in malignant pleural mesothelioma (MM). The present report examines the effect of VEGF on MM growth. Four MM cell lines produced significantly higher VEGF levels than normal mesothelial cells (1946+/-14 pg/ml vs. 180+/-17 pg/ml; p<0.001). In addition, MM cells expressed the tyrosine kinase-related VEGF receptors Flt-1 and KDR. Recombinant human VEGF phosphorylated both Flt-1 and KDR and increased proliferation of all four MM cell lines in a dose-dependent fashion. Neutralizing antibodies against either VEGF, Flt-1 or KDR significantly reduced MM cellular proliferation. In addition, expression of VEGF, Flt-1, and KDR was observed in MM biopsies. Moreover, higher VEGF levels were found in the pleural effusions of MM patients than in the effusions of patients with non-malignant pleural disease (1885.7+/-894.9 pg/ml vs. 266.9+/-180.5 pg/ml; p<0.001). Linear regression analysis showed a significant inverse correlation between serum VEGF levels and MM patient survival (r=0.72; p<0.01). No correlation was found between tumour vessel density and either serum (r=0.26; p=0.42) or pleural effusion (r=0.35; p=0.26) VEGF levels. These results indicate that VEGF, via activation of its tyrosine kinase receptors, may be a key regulator of MM growth. In addition, VEGF production could have an impact on patient survival, not only by promoting tumour angiogenesis but also by directly stimulating tumour growth.

Management of malignant pleural mesothelioma: a critical review

Malignant mesothelioma remains a uniformly fatal disease and best supportive care continues to be the standard treatment. Neither chemotherapy nor surgery has been shown to prolong survival. Radiotherapy is not curative but is useful for prophylaxis against needle-track metastases and for symptom palliation. Combinations of therapies have been tried but most studies were uncontrolled and selection bias makes the results impossible to interpret. The combination of extrapleural pneumonectomy, chemotherapy, and radiotherapy attracted much interest, but the subsequent results were disappointing in a highly selected group of patients. Randomized controlled trials are desperately needed to provide definitive information on experimental treatments. It is also important to develop better measures of disease response and to assess quality of life issues in clinical trials. If patients are to receive therapies other than palliation, they should only do so in the setting of randomized controlled trials under approved protocols.