A randomised trial of single-dose radiotherapy to prevent procedure tract metastasis by malignant mesothelioma

Updates in Management of Malignant Pleural Mesothelioma

OPINION STATEMENT

Malignant pleural mesothelioma (MPM) is an aggressive asbestos-associated thoracic malignancy that is usually incurable. As demonstrated in the landmark MARS2 trial, surgical resection does not improve survival outcomes and its role in managing MPM is limited. Whilst platinum-pemetrexed chemotherapy in combination with bevacizumab was the standard first-line approach for unresectable disease, landmark phase 3 trials have now established the role of immune checkpoint inhibitors (CPIs) in the upfront management of unresectable disease: either nivolumab-ipilimumab or carboplatin-pemetrexed-pembrolizumab. Patient selection for optimal strategy remains an ongoing question. For relapsed disease novel genomic-based therapies targeting a range of aberrations including losses of the tumour suppressor genes BAP1, CDKN2A and NF2, are being evaluated. Nonetheless, the future of MPM therapeutics holds promise. Here we overview current treatment strategies in the management of MPM.

Simultaneous Use of Endobronchial and Endoscopic Ultrasound Guidance as Primary Tools in the Diagnosis of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is related to exposure to asbestos. It is insidious in nature and is generally diagnosed at an advanced stage. MPM is aggressive and portends a poor prognosis. Definitive diagnosis is usually established by obtaining pathological samples of the pleura by medical or surgical thoracoscopy. However, these procedures are invasive and carry a risk of seeding of biopsy sites with tumors. We herein report an infrequently encountered case of simultaneous use of endobronchial ultrasound and endoscopic ultrasound-guided biopsy of malignant pleural mesothelioma in a 48-year-old female patient.

Incidence and Risk Factors of Chest Wall Metastasis at Biopsy Sites in Patients with Malignant Pleural Mesothelioma

To investigate the incidence and risk factors of chest wall metastasis (CWM) at biopsy sites in patients with malignant pleural mesothelioma (MPM). This retrospective cohort study was conducted in 262 consecutive MPM patients who underwent multimodal treatment in which including neoadjuvant chemotherapy (NAC) and curative-intent surgery, from August 2009 to March 2021. CWM was evaluated radiologically (r-CWM) and pathologically (p-CWM). We also investigated the risk factors of p-CWM and the consistency between r-CWM and p-CWM. Of 262 patients, 25 patients were excluded from analysis due to missing data or impossibility of evaluation. Of the eligible 237 patients, pleural biopsy was performed via video-assisted thoracoscopic surgery in 197 (83.1%) and medical thoracoscopy in 40 (16.9%). Pleurodesis was performed after pleural biopsy in 74 patients (31.2%). All patients received NAC followed by curative-intent surgery. Radiological examination showed r-CWM in 43 patients (18.1%), while pathological examination showed p-CWM in 135 patients (57.0%). The incidence of p-CWM was significantly higher in the patients who received pleurodesis after pleural biopsy (77.0% vs. 47.9%, <0.001). Multivariate logistic regression analysis for p-CWM revealed that pleurodesis is an independent risk factor of p-CWM (adjusted hazard ratio, 3.46; 95% confidence interval, 1.84−6.52, <0.001). CWM at the biopsy site was pathologically proven in more than half of the patients (57.0%) who received NAC followed by curative-intent surgery, which was higher than the numbers diagnosed by radiological examinations (p-CWM: 57.0% vs. r-CWM: 18.1%). Pleurodesis after pleural biopsy is an independent risk factor of p-CWM.

Evolution of semi-rigid thoracoscopy

Pleural effusions despite being so common, there is no much literature available regarding definite diagnosis for pleural effusions. Application of Light's criteria changed the approach to pleural effusion and till date remains a very useful step in the diagnosis of pleural effusions. Pleural fluid biochemistry and adenosine deaminase (ADA) enzyme levels play a significant role in the diagnosis of tubercular effusion. Studies have shown that levels of ADA are more often higher in tubercular effusion than in any other cause for it. But ADA levels can also be elevated in other types of parapneumonic effusions (PPEs), especially complicated PPEs. Hence it is difficult to distinguish a tubercular pleural effusion (TPE) from other PPEs based on pleural fluid ADA levels alone. LDH/ADA ratio as an indicator for ruling out tuberculosis was analyzed in few studies with high sensitivity and specificity. The pleural fluid cytology has a varying sensitivity, with a maximum of only 60% and it may increase with subsequent tapping. Closed pleural biopsy using a Cope or Abrams needle has a sensitivity up to 80% in cases of tuberculous effusion and 40%-73% in cases of Malignancies. Semi-rigid thoracoscopy not only allows for visualization of the pleura but also helps in procuring the biopsies under direct visualization from the abnormal looking areas. In cases of primary pleural malignancies like mesothelioma, pleurodesis can also be done in the same setting after taking the biopsy, hence reducing the number of procedures. Limitation of the semi-rigid thoracoscopy is smaller sample size and more superficial sampling of the pleura. Cryobiopsy and Electrocautery guided pleural biopsy using the IT knife are the modifications in the semi-rigid thoracoscopy to overcome the drawback of smaller sample size. While navigation band image guided pleuroscopy helps in better visualization of the vasculature of pleura during the biopsy. Management of pleural effusions has evolved over a period of time. Starting with a single criterion based on pleural fluid proteins to semi-rigid thoracoscopy. The inexhaustible research in this field suggests the desperate need for a gold standard procedure with cost effectiveness in the management of undiagnosed pleural effusions. Semi-rigid thoracoscopy has revolutionized the management of undiagnosed pleural effusions, but it has its own limitations. Various modifications have been proposed and tried to overcome the limitations to make it a cost-effective procedure.

Pleural mesothelioma (PM) - The status of systemic therapy

Pleural mesothelioma (PM) remains a malignancy with poor prognosis. Despite initial disappointing response rates to single-agent chemotherapy, upfront platinum and anti-folate-based combination chemotherapy has remained the backbone of treatment for PM for the last three decades. The role of maintenance chemotherapy remains unclear; switch-maintenance gemcitabine has shown improvements in progression-free but not overall survival. The addition of antiangiogenic agents to chemotherapy yielded modest improvements in survival, both upfront in combination with platinum-pemetrexed, and in the relapsed setting. Immunotherapy, particularly PD-(L)1 inhibitors, has shown important but variable effectiveness in relapsed PM when used as monotherapy, and is an important salvage treatment after first-line chemotherapy. Furthermore, the randomized phase 3 trial of ipilimumab-nivolumab versus platinum-pemetrexed chemotherapy demonstrated improved overall survival favouring ipilimumab-nivolumab (HR 0.74, 96.6% CI 0.60-0.91; p = 0.0020), establishing this regimen as the new standard first-line treatment for PM, particularly in those with non-epithelioid histology. Increased interest in PM genomics has led to development of novel personalized therapeutics, such as those targeting DNA repair and EZH2 pathways, however with variable outcomes in trials. Targeting the membrane glycoprotein mesothelin and arginine deprivation are other important strategies under ongoing investigation. The field of PM is changing and new treatments bring hope to a largely lethal and poor prognostic malignancy. Despite these developments, current challenges include understanding the role of combination and multimodality treatments, drivers of resistance to treatment, and establishing predictive biomarkers to improve patient selection and treatment sequencing.

ERS/ESTS/EACTS/ESTRO guidelines for the management of malignant pleural mesothelioma

The European Respiratory Society (ERS)/European Society of Thoracic Surgeons (ESTS)/European Association for Cardio-Thoracic Surgery (EACTS)/European Society for Radiotherapy and Oncology (ESTRO) task force brought together experts to update previous 2009 ERS/ESTS guidelines on management of malignant pleural mesothelioma (MPM), a rare cancer with globally poor outcome, after a systematic review of the 2009-2018 literature. The evidence was appraised using the Grading of Recommendations, Assessment, Development and Evaluation approach. The evidence syntheses were discussed and recommendations formulated by this multidisciplinary group of experts. Diagnosis: pleural biopsies remain the gold standard to confirm the diagnosis, usually obtained by thoracoscopy but occasionally via image-guided percutaneous needle biopsy in cases of pleural symphysis or poor performance status. Pathology: standard staining procedures are insufficient in ∼10% of cases, justifying the use of specific markers, including BAP-1 and CDKN2A (p16) for the separation of atypical mesothelial proliferation from MPM. Staging: in the absence of a uniform, robust and validated staging system, we advise using the most recent 2016 8th TNM (tumour, node, metastasis) classification, with an algorithm for pretherapeutic assessment. Monitoring: patient's performance status, histological subtype and tumour volume are the main prognostic factors of clinical importance in routine MPM management. Other potential parameters should be recorded at baseline and reported in clinical trials. Treatment: (chemo)therapy has limited efficacy in MPM patients and only selected patients are candidates for radical surgery. New promising targeted therapies, immunotherapies and strategies have been reviewed. Because of limited data on the best combination treatment, we emphasize that patients who are considered candidates for a multimodal approach, including radical surgery, should be treated as part of clinical trials in MPM-dedicated centres.

Controversies in the role of radiotherapy in pleural mesothelioma

Malignant pleural mesothelioma is an uncommon thoracic cancer with a relatively poor outcome, which has only seen modest improvements when compared to non-small cell lung cancer. The mainstays of treatment have been surgery and systemic therapy, with radiation reserved for palliation or as an adjunct. However, there is re-emergent interest in the use of radiotherapy in the treatment of mesothelioma, given recent technical advances in radiotherapy delivery which permit increased treatment accuracy. This overview article reviews the radiobiology of the mesothelioma and whether or not mesothelioma is an inherently radioresistant cancer and the potential impact that hypofractionation may have on different histological subtypes in mesothelioma. This overview also considers the role of radiation in palliation, as adjunct to surgical resection and as adjunct to pleural tract procedures. In particular we review the growing evidence that pleural tract or port site adjuvant radiotherapy provides no clinical benefit. This overview will also consider potential emerging therapeutic strategies such as pre-operative short course hypofractionated radiotherapy. The role of novel radiotherapy techniques such as stereotactic ablative radiotherapy, image guided radiotherapy, proton therapy and the potential role of radiotherapy as an immune stimulating agent in combination of immunotherapy, will also be discussed. Finally, given the many unanswered questions, this review discusses some of the emerging and ongoing clinical trials of radiotherapy in the treatment of mesothelioma.

Prophylactic irradiation of tracts in patients with malignant pleural mesothelioma: A systematic review and meta-analysis of randomized trials

INTRODUCTION

The role of prophylactic irradiation of tracts (PIT) to prevent tumor seeding at the site of a diagnostic or therapeutic intervention in patients with malignant pleural mesothelioma (MPM) is controversial. This study aimed to determine the efficacy of PITs in preventing procedure tract metastases (PTM) after a chest wall procedure in MPM.

MATERIALS AND METHODS

We searched various databases from inception date to April 2020 for randomized controlled trials (RCTs) comparing PIT with no PIT in patients who had a chest wall procedure for MPM. We assessed the risk of bias of individual RCT using the RoB2 tool. The primary outcome was the occurrence of PTM. Meta-analysis was performed using random-effects model. We employed the GRADE approach to assess the certainty of the evidence.

RESULTS

We identified five RCTs including 737 patients. Two RCTs had a low risk of bias. PIT was associated with a significant reduction in the odds of PTM (odd ratio, 0.55; 95 % confidence interval, 0.32 to 0.95; P-value = 0.03; I² = 13 %; GRADE: moderate certainty). One RCT reported no difference in overall survival outcome with the use of PIT. None of the RCTs performed subgroup analyses. Sensitivity analyses showed similar results when limited to RCTs with low risk of bias.

CONCLUSION

PIT significantly reduces the occurrence of PTM in patients with MPM who had a diagnostic or therapeutic chest wall procedure.

A Review of Pharmacologic Management in the Treatment of Mesothelioma

OPINION STATEMENT

Mesothelioma is a rare and severe form of cancer that is associated with asbestos exposure. Approximately 2500 Americans die annually from this condition with a median survival of 1 year. The latency period of this disease ranges anywhere from 20 to 70 years, with shorter latency periods associated with a higher exposure intensity to asbestos. Therefore, cases of mesothelioma are expected in the coming decades. This highlights the need for clinicians to understand the pharmacologic regimens available for treating this rare, yet serious malignancy. With multiple treatment regimens available in the treatment of this condition, clinicians should take an evidence-based approach and consider the totality of evidence and safety information while considering the best patient-centered approach for treatment. This article provides a review of current pharmacologic treatment options available for mesothelioma and goes into detail about the recommended medication regimens and dosages and the available evidence of efficacy, effectiveness, and/or safety and estimates the annual cost of treatment for these medications on the U.S. healthcare system per patient. A brief introduction is provided for several promising agents currently under investigation for mesothelioma as well.

Simultaneous tongue metastasis from malignant pleural mesothelioma: Case report and literature review

Malignant pleural mesothelioma (MPM) is a rare neoplasm of the serosal membranes. MPM usually manifests as local invasion, rarely with distant haematogenous metastases in different organs. Few cases of tongue metastasis have been documented. Here, we report the case of a 68-year-old man diagnosed with malignant pleural epithelioid mesothelioma together with a simultaneous tongue lesion, which was found to be metastatic malignant mesothelioma. Tongue metastasis from MPM is rare and the oral symptoms it causes could be an early sign of clinical manifestation. For patients with oral symptoms and a newly discovered tongue lesion, clinicians should be aware of the possibility of tongue metastasis and search for a primary malignancy.

ERS/ESTS/EACTS/ESTRO guidelines for the management of malignant pleural mesothelioma

The European Respiratory Society (ERS)/European Society of Thoracic Surgeons (ESTS)/European Association for Cardio-Thoracic Surgery (EACTS)/European Society for Radiotherapy and Oncology (ESTRO) task force brought together experts to update previous 2009 ERS/ESTS guidelines on management of malignant pleural mesothelioma (MPM), a rare cancer with globally poor outcome, after a systematic review of the 2009-2018 literature. The evidence was appraised using the Grading of Recommendations, Assessment, Development and Evaluation approach. The evidence syntheses were discussed and recommendations formulated by this multidisciplinary group of experts. Diagnosis: pleural biopsies remain the gold standard to confirm the diagnosis, usually obtained by thoracoscopy but occasionally via image-guided percutaneous needle biopsy in cases of pleural symphysis or poor performance status. Pathology: standard staining procedures are insufficient in ∼10% of cases, justifying the use of specific markers, including BAP-1 and CDKN2A (p16) for the separation of atypical mesothelial proliferation from MPM. Staging: in the absence of a uniform, robust and validated staging system, we advise using the most recent 2016 8th TNM (tumour, node, metastasis) classification, with an algorithm for pre-therapeutic assessment. Monitoring: patient's performance status, histological subtype and tumour volume are the main prognostic factors of clinical importance in routine MPM management. Other potential parameters should be recorded at baseline and reported in clinical trials. Treatment: (chemo)therapy has limited efficacy in MPM patients and only selected patients are candidates for radical surgery. New promising targeted therapies, immunotherapies and strategies have been reviewed. Because of limited data on the best combination treatment, we emphasise that patients who are considered candidates for a multimodal approach, including radical surgery, should be treated as part of clinical trials in MPM-dedicated centres.

Scientific Advances and New Frontiers in Mesothelioma Therapeutics

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer that arises from the mesothelial surface of the pleural and peritoneal cavities, the pericardium, and rarely, the tunica vaginalis. The incidence of MPM is expected to increase worldwide in the next two decades. However, even with the use of multimodality treatment, MPM remains challenging to treat, with a 5-year survival rate of less than 5%. The International Association for the Study of Lung Cancer has gathered experts in different areas of mesothelioma research and management to summarize the most significant scientific advances and new frontiers related to mesothelioma therapeutics.

The use of indwelling pleural catheters for the treatment of malignant pleural effusions

Introduction: The presence of a malignant pleural effusion (MPE) is a marker of advanced disease and associated with a poor prognosis. Patients are in a palliative stage of their disease and often suffer distressing symptoms including breathlessness and pain. Indwelling pleural catheters (IPCs) are effective in managing pleural effusions and allow ambulatory drainage of the pleural space, reducing symptoms associated with effusions and lowering overall hospital stay. The role of IPCs as a first line option in managing MPEs is expanding with a multitude of recent studies into the optimal application of IPCs, necessitating a review of the current literature. Areas covered: This article will provide an overview of IPCs in MPE; how they're inserted, their indications, continuing management, complications and possible future applications. Expert opinion: IPCs should be considered first-line management of MPEs, alongside standard talc pleurodesis. Recognition of the advantages and disadvantages of each approach allows a more informed patient choice. It is recognized that the use of IPCs can provoke pleurodesis, leading to removal of the catheter. For patients in whom prompt removal of the catheter is a priority, then a more aggressive drainage regime or instillation of talc via the IPC is a reasonable option.

Pain management in patients with malignant mesothelioma: challenges and solutions

Malignant pleural mesothelioma (MPM) is an aggressive cancer with a considerable symptom burden and poor prognosis. Focus on maintaining patients’ quality of life and pain control is therefore paramount. Pain management in MPM is complex due to its multifactorial etiology resulting from direct tumor infiltration of the surrounding soft tissue, bone, and encasement of the intercostal nerves. A variety of treatment modalities, including pharmacological and non-pharmacological options, are often required to achieve adequate pain control in this challenging disease. This review article examines the current challenges and solutions available for pain management in MPM.

Prophylactic Irradiation of Tracts in Patients With Malignant Pleural Mesothelioma: An Open-Label, Multicenter, Phase III Randomized Trial

PURPOSE

Prophylactic irradiation to the chest wall after diagnostic or therapeutic procedures in patients with malignant pleural mesothelioma (MPM) has been a widespread practice across Europe, although the efficacy of this treatment is uncertain. In this study, we aimed to determine the efficacy of prophylactic radiotherapy in reducing the incidence of chest wall metastases (CWM) after a procedure in MPM.

METHODS

After undergoing a chest wall procedure, patients with MPM were randomly assigned to receive prophylactic radiotherapy (within 42 days of the procedure) or no radiotherapy. Open thoracotomies, needle biopsies, and indwelling pleural catheters were excluded. Prophylactic radiotherapy was delivered at a dose of 21 Gy in three fractions over three consecutive working days, using a single electron field adapted to maximize coverage of the tract from skin surface to pleura. The primary outcome was the incidence of CWM within 6 months from random assignment, assessed in the intention-to-treat population. Stratification factors included epithelioid histology and intention to give chemotherapy.

RESULTS

Between July 30, 2012, and December 12, 2015, 375 patients were recruited from 54 centers and randomly assigned to receive prophylactic radiotherapy (n = 186) or no prophylactic radiotherapy (n = 189). Participants were well matched at baseline. No significant difference was seen in the incidence of CWM at 6 months between the prophylactic radiotherapy and no radiotherapy groups (no. [%]: 6 [3.2] v 10 [5.3], respectively; odds ratio, 0.60; 95% CI, 0.17 to 1.86; P = .44). Skin toxicity was the most common radiotherapy-related adverse event in the prophylactic radiotherapy group, with 96 patients (51.6%) receiving grade 1; 19 (10.2%), grade 2; and 1 (0.5%) grade 3 radiation dermatitis (Common Terminology Criteria for Adverse Events, version 4.0).

CONCLUSION

There is no role for the routine use of prophylactic irradiation to chest wall procedure sites in patients with MPM.

Current treatment strategies in malignant pleural mesothelioma with a treatment algorithm

Malignant pleural mesothelioma (MPM) is arare disease with apoor prognosis. The main therapeutic options for MPM include surgery, chemotherapy, and radiation therapy (RT). Although multimodality therapy has been reported to improve survival, not every medically operable patient is able to undergo all recommended therapy. With improvements in surgical techniques and systemic therapies, as well as advancements in RT, there has been apotential new paradigm in the management of this disease. In this review, we discuss the current literature on MPM management and propose afunctional treatment algorithm.

A Novel Prospective Study Assessing the Combination of Photodynamic Therapy and Proton Radiation Therapy: Safety and Outcomes When Treating Malignant Pleural Mesothelioma

Malignant pleural mesothelioma remains difficult to treat, with high failure rates despite optimal therapy. We present a novel prospective trial combining proton therapy (PT) and photodynamic therapy (PDT) and the largest-ever mesothelioma PT experience (n = 10). PDT photosensitizers included porfimer sodium (2 mg·kg-1 ; 24 h drug-light interval) or 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) (4 mg·m-2 ;48 h) with wavelengths of 630 nm to 60J·cm-2 and 665 nm to 15-45J·cm-2 , respectively. With a median age of 69 years, patients were predominantly male (90%) with epithelioid histology (100%) and stage III-IV disease (100%). PT was delivered to a median of 55.0 CGE/1.8-2.0 CGE (range 50-75 CGE) adjuvantly (n = 8) or as salvage therapy (n = 2) following extended pleurectomy/decortication (ePD)/PDT. Two-year local control was 90%, with distant and regional failure rates of 50% and 30%, respectively. All patients received chemotherapy, and four received immunotherapy. Surgical complications included atrial fibrillation (n = 3), pneumonia (n = 2), and deep vein thrombosis (n = 2). Median survival from PT completion was 19.5 months (30.3 months from diagnosis), and 1- and 2-year survival rates were 58% and 29%. No patient experienced CTCAEv4 grade ≥2 acute or late toxicity. Our prolonged survival in very advanced-stage patients compares favorably to survival for PT without PDT and photon therapy with PDT, suggesting possible spatial or systemic cooperativity and immune effect.

Is there a role for prophylactic radiotherapy to intervention tract sites in patients with malignant pleural mesothelioma?

Malignant pleural mesothelioma has a high morbidity and poor prognosis. Most patients undergo invasive pleural interventions to either facilitate diagnosis and/or alleviate symptoms from malignant pleural effusion. Procedure tract metastasis (PTM) are a well-known complication of pleural procedures in mesothelioma and there has been longstanding debate regarding the role of prophylactic irradiation of tracts in preventing them. This review summarises the existing evidence surrounding this controversial topic. Despite initial discrepancies amongst the results of 3 small, historical trials regarding the efficacy of prophylactic radiotherapy in mesothelioma, two large randomised-control trials have recently provided more clarity. The SMART trial, which randomised over 200 patients, found no benefit of prophylactic radiotherapy in reducing PTM incidence in their primary analysis, with a number needed to treat (NNT) of 25.1 to prevent a single painful PTM. Additionally, there was no benefit in terms of symptomology, health-related quality of life parameters or cost-effectiveness. This is supported by the preliminary results of the Prophylactic Irradiation of Tracts in Patients with Pleural Mesothelioma (PIT) trial, which randomised 375 patients and also found no evidence that prophylactic radiotherapy reduced PTM incidence, although the full results are still awaited. Combined analysis of these trials is planned, which will help clarify whether specific subpopulations may derive benefit from prophylactic radiotherapy, such as patients not receiving chemotherapy. Based on the currently available evidence there is no role for routine delivery of prophylactic radiotherapy to prevent PTM in mesothelioma. Instead holistic and vigilant follow-up of patients is recommended, aiming for adequate palliation of symptoms and support for patients. Should painful nodules develop these can be effectively treated with subsequent palliative radiotherapy. After years of uncertainty and debate, recent international guidelines have consistently advised against the use of prophylactic irradiation of tracts based on contemporary high-quality evidence.

Prophylactic procedure tract radiotherapy for malignant pleural mesothelioma: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Malignant pleural mesothelioma (MPM) is an aggressive cancer with a propensity for seeding procedure tracts, leading to symptomatic metastases. There is conflicting evidence on the value of prophylactic procedure tract radiotherapy in reducing tract metastases. We performed a systematic review and meta-analysis to estimate the benefit of radiotherapy in this setting.

MATERIALS AND METHODS

Electronic databases were searched to January 1, 2018 for prospective randomized control trials with prophylactic procedure tract radiotherapy as the intervention arm. Pooled odds ratios and 95% confidence intervals were calculated using a random effects model. Study heterogeneity was assessed using the I2 statistic, and publication bias was evaluated by funnel plot and Egger's regression model.

RESULTS

Five studies were included for meta-analysis. Prophylactic radiotherapy did not have a statistically significant reduction on the risk of procedure site recurrence, with a pooled relative risk of 0.69 (95% CI 0.33-1.43). There was moderate heterogeneity between trials. All trials were assessed as moderate or high risk of bias overall.

CONCLUSION

This systematic review has confirmed that there is no role for prophylactic procedure tract radiotherapy in MPM. In the absence of effective prophylactic procedures, patients need to be monitored closely, and palliative interventions delivered in a timely manner to reduce morbidity associated with procedure tract metastases.

Adjuvant, neoadjuvant, and definitive radiation therapy for malignant pleural mesothelioma

While ionizing radiotherapy (RT) can provide durable local control, the relative radiosensitivity of surrounding organs such as the lungs and heart and the distributed nature of the pleura limit the ability to safely deliver RT for patients with malignant pleural mesothelioma (MPM). Recent advances in the technological sophistication of RT planning and delivery devices have resulted in increased spatial control of irradiation dose that has extended the palliative and definitive applications of RT for patients with MPM. This review will outline the logistical, mechanistic and clinical basics of RT and the clinical trials supporting the use of RT in the multidisciplinary care of patients with MPM.

Proton beam therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare disease with a poor prognosis. Surgical techniques have made incremental improvements over the last few decades while new systemic therapies, including immunotherapies, show promise as potentially effective novel therapies. Radiation therapy has historically been used only in the palliative setting or as adjuvant therapy after extrapleural pneumonectomy, but recent advances in treatment planning and delivery techniques utilizing intensity-modulated radiation therapy and more recently pencil-beam scanning (PBS) proton therapy, have enabled the delivery of radiation therapy as neoadjuvant or adjuvant therapy after an extended pleurectomy and decortication or as definitive therapy for patients with recurrent or unresectable disease. In particular, PBS proton therapy has the potential to deliver high doses of irradiation to the entire effected pleura while significantly reducing doses to nearby organs at risk. This article describes the evolution of radiation therapy for MPM and details how whole-pleural PBS proton therapy is delivered to patients at the Maryland Proton Treatment Center.

Prophylactic radiotherapy for procedure tract metastases in mesothelioma: a review

PURPOSE OF REVIEW

Malignant pleural mesothelioma is an aggressive malignancy with a very poor prognosis. The majority of patients require pleural procedures for diagnostic or fluid management purposes. Damage to the pleura during these procedures can lead to procedure tract metastases (PTMs), with increasing risk from larger interventions. Prophylactic radiotherapy to these sites is a controversial topic with conflicting results from trial data. In this review, we summarize the recent evidence.

RECENT FINDINGS

Four RCTs have been published on this topic, with another in follow-up. The earliest, from a cohort of 40 patients, strongly advocated the use of prophylactic radiotherapy. More recent trials, most notably the Surgical and large bore procedures in Malignant pleural mesothelioma And Radiotherapy Trial (SMART) (which randomized over 200 patients) did not demonstrate any benefit, especially when patient report symptoms and cost-effectiveness are considered. Certain subgroups demand further investigation, such as those not receiving systematic chemotherapy or with surgical intervention sites. The soon to be published Prophylactic Irradiation of Tracts (PIT) trial may help to further clarify best practice.

SUMMARY

Recent studies have shown that prophylactic radiotherapy should not be routinely used to prevent PTMs in mesothelioma. Instead patients should undergo careful clinical follow-up to ensure PTMs are identified and treated promptly to minimize symptoms.

Evaluating quality of life and cost implications of prophylactic radiotherapy in mesothelioma: Health economic analysis of the SMART trial

BACKGROUND

The SMART trial is a UK-based, multicentre RCT comparing prophylactic radiotherapy and symptom-based (deferred) radiotherapy in 203 patients with Malignant Pleural Mesothelioma who had undergone large bore pleural interventions. Using costs and quality of life data collected alongside the clinical trial, we will estimate the cost-effectiveness of prophylactic radiotherapy compared to deferred radiotherapy over a 1-year period.

METHODS

Healthcare utilization and costs were captured during the trial. Utility weights produced by the EQ-5D questionnaire were used to determine quality-adjusted life-years (QALY) gained. The incremental cost-effectiveness ratio was calculated over the one-year trial period.

RESULTS

Costs were similar in the immediate and deferred radiotherapy groups: £5480.40 (SD = £7040; n = 102) and £5461.40 (SD = £7770; n = 101) respectively. There was also no difference in QALY: 0.498 (95% CI: [0.45, 0.547]) in the prophylactic radiotherapy group versus 0.525 (95% CI: [0.471, 0.580]) in the deferred group. At a willingness to pay threshold of £30,000/QALY there was only a 24% chance that prophylactic radiotherapy was cost-effective compared to deferred radiotherapy.

CONCLUSIONS

There was no significant effect of prophylactic radiotherapy on quality of life in the intervention group, nor was there any discernable decrease in healthcare costs. There is little evidence to suggest that prophylactic radiotherapy is a cost-effective intervention in this population.

TRIAL REGISTRATION

ISRCTN72767336 with ISRCTN.

Treatment of Malignant Pleural Mesothelioma: American Society of Clinical Oncology Clinical Practice Guideline

Purpose To provide evidence-based recommendations to practicing physicians and others on the management of malignant pleural mesothelioma. Methods ASCO convened an Expert Panel of medical oncology, thoracic surgery, radiation oncology, pulmonary, pathology, imaging, and advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 1990 through 2017. Outcomes of interest included survival, disease-free or recurrence-free survival, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. Results The literature search identified 222 relevant studies to inform the evidence base for this guideline. Recommendations Evidence-based recommendations were developed for diagnosis, staging, chemotherapy, surgical cytoreduction, radiation therapy, and multimodality therapy in patients with malignant pleural mesothelioma. Additional information is available at www.asco.org/thoracic-cancer-guidelines and www.asco.org/guidelineswiki .

[Prophylactic radiotherapy in a single fraction of 10Gy at intervention pleural site in patient with malignant pleural mesothelioma: A retrospective monocentric cohort study]

PURPOSE

Prophylactic radiotherapy to prevent procedure-tracts metastases from malignant pleural mesothelioma remains controversial and clinical practice varies. The purpose was to assess the efficacy of local radiotherapy in a single fraction of 10Gy in preventing malignant seeding at intervention pleural site in patients with malignant pleural mesothelioma.

MATERIAL AND METHODS

This is a retrospective cohort study, including patients with histological confirmed malignant pleural mesothelioma treated by prophylactic irradiation to prevent interventional site metastases with a unique fraction of 10Gy with 6 to 18MeV, from January 1990 to December 2013 in the institut de cancérologie de Lorraine (Nancy, France).

RESULTS

Ninety-one patients were treated by irradiation in intervention site, involving 120 intervention pleural sites, 91 thoracoscopies, 17 thoracotomies with chest drain and 12 CT or ultrasound guided needle biopsies. The median follow-up was 7 months (interquartile between 3 and 15 months). The overall survival was 43.5% at 12 months. The local progression free survival was 43.7% at 12 month. The incidence of local recurrence was 8% at 12 months. The median interval from radiotherapy to local recurrence was 4 months (2; 32). No grade II or higher toxicity was observed.

CONCLUSION

Irradiation of pleural intervention sites with a single fraction of 10Gy is effective, well tolerated, simple, fast and cost effective.

Radiotherapy for the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive disease that continues to be associated with poor outcomes. Although, traditionally this disease is considered to be resistant to radiotherapy, more recent evidence suggests that radiotherapy can produce positive outcomes. Over the past 15 years, the development of new, highly conformal radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), has enabled investigators to optimise the delivery of high-dose radiotherapy to the whole of the hemithorax. Prospective single-arm trials have shown that the median survival of patients who have completed high-dose hemithoracic radiotherapy after extrapleural pneumonectomy could reach 23·9-39·4 months independent of the chemotherapeutic response, suggesting that IMRT could potentially have an intrinsic benefit to this subset of patients. These observations have led to a change in practice, with the introduction of adjuvant pleural IMRT after pleurectomy-decortication and the development of induction-accelerated hemithoracic IMRT followed by extrapleural pneumonectomy. This Review focuses on recent observations on the role of radiotherapy in the treatment of malignant pleural mesothelioma, with particular emphasis on the results of clinical trials that evaluate the role of high-dose hemithoracic radiotherapy.

The role of radical radiotherapy in the management of malignant pleural mesothelioma: A systematic review

Malignant pleural mesothelioma (MPM) is a devastating disease with limited treatment options and a dismal prognosis. Attempts to employ radical radiotherapy in this disease have been limited by the complex shape of the pleura and the dose restrictions necessitated by the close proximity of radiosensitive structures. Recent shifts towards a 'lung sparing' surgical approach in MPM have further heightened these challenges. The aim of this systematic review is to assess recent advances in radiotherapy planning and delivery, to ascertain how these developments have impacted on the feasibility of delivering photon-based, high-dose radiotherapy with radical intent in MPM. Three electronic databases were searched and a total of 249 articles reviewed. The challenge of generating high quality, practice-defining data for diseases such as MPM was highlighted by the identification of just two randomised studies. Much of the literature consisted of low quality, retrospective data with small cohorts and inconsistent reporting on radiotherapy techniques and dosimetry. Nevertheless, a number of prospective phase II studies were identified to suggest that radical doses of radiotherapy can be delivered safely after a lung sparing procedure in MPM, reporting encouraging survival data and acceptable levels of toxicity.

Malignant pleural mesothelioma: an update on investigation, diagnosis and treatment

Malignant pleural mesothelioma is an aggressive malignancy of the pleural surface, predominantly caused by prior asbestos exposure. There is a global epidemic of malignant pleural mesothelioma underway, and incidence rates are predicted to peak in the next few years.

This article summarises the epidemiology and pathogenesis of malignant pleural mesothelioma, before describing some key factors in the patient experience and outlining common symptoms. Diagnostic approaches are reviewed, including imaging techniques and the role of various biomarkers. Treatment options are summarised, including the importance of palliative care and methods of controlling pleural effusions. The evidence for chemotherapy, radiotherapy and surgery is reviewed, both in the palliative setting and in the context of trimodality treatment. An algorithm for managing malignant pleural effusion in malignant pleural mesothelioma patients is presented. Finally new treatment developments and novel therapeutic approaches are summarised.

This article on mesothelioma describes pathogenesis, symptoms, diagnostic approaches and treatment optionshttp://ow.ly/cjkb305aQGz

A Single-Institution Experience in Percutaneous Image-Guided Biopsy of Malignant Pleural Mesothelioma

PURPOSE

Mesothelioma has been considered a difficult pathologic diagnosis to achieve via image-guided core needle biopsy. The purpose of this study was to assess the diagnostic sensitivity of percutaneous image-guided biopsy for diagnosis of pleural mesothelioma.

MATERIALS AND METHODS

Retrospective review was performed to identify patients with a confirmed diagnosis of pleural mesothelioma and who underwent image-guided needle biopsy between January 1, 2002, and January 1, 2016. Thirty-two patients with pleural mesothelioma were identified and included for analysis in 33 image-guided biopsy procedures. Patient, procedural, and pathologic characteristics were recorded. Complications were characterized via standardized nomenclature [Common Terminology for Clinically Adverse Events (CTCAE)].

RESULTS

Percutaneous image-guided biopsy was associated with an overall sensitivity of 81%. No CTCAE clinically significant complications were observed. No image-guided procedures were complicated by pneumothorax or necessitated chest tube placement. No patients had tumor seeding of the biopsy tract.

CONCLUSION

Percutaneous image-guided biopsy can achieve high sensitivity for pathologic diagnosis of pleural mesothelioma with a low procedural complication rate, potentially obviating need for surgical biopsy.

Pleural procedures in the management of malignant effusions

Malignant pleural effusion (MPE) is common in clinical practice, and despite the existence of studies to guide clinical decisions, it often poses diagnostic and therapeutic dilemmas. Once it is diagnosed, median survival does not usually exceed 6 months. The management of these patients focuses on symptom relief since no treatments have been shown to increase survival to date. Conversely, poor management can shorten survival. The approach must be multidisciplinary and allow for individualized care. Initial diagnostic procedures should be minimally invasive and, according to the results and other factors, procedures of increasing complexity will be selecting. Likewise, the treatment of MPEs should be individualized according to factors such as type of tumor, patient functional status, means available, benefits of each procedure, or life expectancy. Currently, treatment seems to tend toward less interventional approaches, in which patients can be managed on an outpatient basis, thus minimizing both the discomfort that more aggressive approaches involve and the costs of care associated with this disease. This article reviews the pleural procedures employed in the management of MPEs with special emphasis on the indication for each one, its usefulness, benefits, and complications.

Prophylactic radiotherapy for the prevention of procedure-tract metastases after surgical and large-bore pleural procedures in malignant pleural mesothelioma (SMART): a multicentre, open-label, phase 3, randomised controlled trial

BACKGROUND

The use of prophylactic radiotherapy to prevent procedure-tract metastases (PTMs) in malignant pleural mesothelioma remains controversial, and clinical practice varies worldwide. We aimed to compare prophylactic radiotherapy with deferred radiotherapy (given only when a PTM developed) in a suitably powered trial.

METHODS

We did a multicentre, open-label, phase 3, randomised controlled trial in 22 UK hospitals of patients with histocytologically proven mesothelioma who had undergone large-bore pleural interventions in the 35 days prior to recruitment. Eligible patients were randomised (1:1), using a computer-generated sequence, to receive immediate radiotherapy (21 Gy in three fractions within 42 days of the pleural intervention) or deferred radiotherapy (same dose given within 35 days of PTM diagnosis). Randomisation was minimised by histological subtype, surgical versus non-surgical procedure, and pleural procedure (indwelling pleural catheter vs other). The primary outcome was the incidence of PTM within 7 cm of the site of pleural intervention within 12 months from randomisation, assessed in the intention-to-treat population. This trial is registered with ISRCTN, number ISRCTN72767336.

FINDINGS

Between Dec 23, 2011, and Aug 4, 2014, we randomised 203 patients to receive immediate radiotherapy (n=102) or deferred radiotherapy (n=101). The patients were well matched at baseline. No significant difference was seen in PTM incidence in the immediate and deferred radiotherapy groups (nine [9%] vs 16 [16%]; odds ratio 0·51 [95% CI 0·19-1·32]; p=0·14). The only serious adverse event related to a PTM or radiotherapy was development of a painful PTM within the radiotherapy field that required hospital admission for symptom control in one patient who received immediate radiotherapy. Common adverse events of immediate radiotherapy were skin toxicity (grade 1 in 50 [54%] and grade 2 in four [4%] of 92 patients vs grade 1 in three [60%] and grade 2 in two [40%] of five patients in the deferred radiotherapy group who received radiotherapy for a PTM) and tiredness or lethargy (36 [39%] in the immediate radiotherapy group vs two [40%] in the deferred radiotherapy group) within 3 months of receiving radiotherapy.

INTERPRETATION

Routine use of prophylactic radiotherapy in all patients with mesothelioma after large-bore thoracic interventions is not justified.

FUNDING

Research for Patient Benefit Programme from the UK National Institute for Health Research.

The Third Italian Consensus Conference for Malignant Pleural Mesothelioma: State of the art and recommendations

Malignant Pleural Mesothelioma (MPM) remains a relevant public health issue, and asbestos exposure is the most relevant risk factor. The incidence has considerably and constantly increased over the past two decades in the industrialized countries and is expected to peak in 2020-2025. In Italy, a standardized-rate incidence in 2011 among men was 3.5 and 1.25 per 100,000 in men and women, respectively, and wide differences are noted among different geographic areas. The disease remains challenging in terms of diagnosis, staging and treatment and an optimal strategy has not yet been clearly defined. The Third Italian Multidisciplinary Consensus Conference on Malignant Pleural Mesothelioma was held in Bari (Italy) in January 30-31, 2015. This Consensus has provided updated recommendations on the MPM management for health institutions, clinicians and patients.

Protocol for PIT: a phase III trial of prophylactic irradiation of tracts in patients with malignant pleural mesothelioma following invasive chest wall intervention

INTRODUCTION

Histological diagnosis of malignant mesothelioma requires an invasive procedure such as CT-guided needle biopsy, thoracoscopy, video-assisted thorascopic surgery (VATs) or thoracotomy. These invasive procedures encourage tumour cell seeding at the intervention site and patients can develop tumour nodules within the chest wall. In an effort to prevent nodules developing, it has been widespread practice across Europe to irradiate intervention sites postprocedure--a practice known as prophylactic irradiation of tracts (PIT). To date there has not been a suitably powered randomised trial to determine whether PIT is effective at reducing the risk of chest wall nodule development.

METHODS AND ANALYSIS

In this multicentre phase III randomised controlled superiority trial, 374 patients who can receive radiotherapy within 42 days of a chest wall intervention will be randomised to receive PIT or no PIT. Patients will be randomised on a 1:1 basis. Radiotherapy in the PIT arm will be 21 Gy in three fractions. Subsequent chemotherapy is given at the clinicians' discretion. A reduction in the incidence of chest wall nodules from 15% to 5% in favour of radiotherapy 6 months after randomisation would be clinically significant. All patients will be followed up for up to 2 years with monthly telephone contact and at least four outpatient visits in the first year.

ETHICS AND DISSEMINATION

PIT was approved by NRES Committee North West-Greater Manchester West (REC reference 12/NW/0249) and recruitment is currently on-going, the last patient is expected to be randomised by the end of 2015. The analysis of the primary end point, incidence of chest wall nodules 6 months after randomisation, is expected to be published in 2016 in a peer reviewed journal and results will also be presented at scientific meetings and summary results published online. A follow-up analysis is expected to be published in 2018.

TRIAL REGISTRATION NUMBER

ISRCTN04240319; NCT01604005; Pre-results.

Pseudo-tumor mimicking indwelling pleural catheter tract metastasis in mesothelioma

Patients with malignant mesothelioma are known to be at risk of developing needle tract metastasis from seeding of malignant cells at the pleural intervention site. Histologic confirmation of needle tract metastases is seldom sought. The diagnosis and management (often radiotherapy) are almost always based on clinical judgment of new subcutaneous lesions at prior pleural puncture sites in mesothelioma patients. We report 2 patients with mesothelioma who developed new subcutaneous nodules at their indwelling pleural catheter insertion site, mimicking tract metastases. Biopsies of both lesions revealed benign etiologies and both resolved without requiring irradiation. These cases remind clinicians that new subcutaneous lesions can be benign even when arising at pleural puncture sites of malignant pleural mesothelioma patients. Percutaneous biopsy can clarify the diagnosis in suitable cases.

Radiation therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive tumor where the ability to control the primary tumor (local control) presents a significant challenge. External beam radiation has the potential to improve local control when following established safe and effective protocols. Radiation is primarily used as adjuvant treatment after extrapleural pneumonectomy or pleurectomy/decortication and as palliative treatment in some cases. The target volume for radiotherapy of malignant pleural mesothelioma can be quite extensive and thus toxicity is its chief limitation.

Pleural controversies: image guided biopsy vs. thoracoscopy for undiagnosed pleural effusions?

Undiagnosed pleural effusions present an increasing diagnostic burden upon healthcare providers internationally. The investigation of pleural effusions often requires the acquisition of tissue for histological analysis and diagnosis. Historically there were two options for tissue biopsy: a 'gold standard' surgical biopsy or a "blind" closed pleural biopsy. Over the last decade however, image-guided Tru-cut biopsies and local anaesthetic thoracoscopic (local anaesthetic thoracoscopy) biopsies have become more widespread. Image-guided techniques acquire samples under ultrasound (US) or computed tomography (CT) guidance whereas LAT involves the direct visualisation and biopsy of the pleura with pleuroscopy. Both techniques have been shown to be superior to 'blind' closed pleural biopsy for the diagnosis of pleural or metastatic malignancy. However, closed biopsy remains a viable method of investigation in areas of high incidence of tuberculosis (TB). Beyond this, each investigative technique has its own advantages and disadvantages. Image-guided biopsy is less invasive, usually carried out as an outpatient procedure, and enables tissue biopsy in frail patients and those with pleural thickening but no pleural fluid. Local anaesthetic thoracoscopy (LAT) provides diagnostic and therapeutic capabilities in one procedure. Large volume thoracentesis, multiple pleural biopsies and talc poudrage can be carried out in a single procedure. The overall diagnostic yield is similar for both techniques, although there are no large-scale direct comparisons. Both techniques share low complication rates.

Intratumoral macrophage phenotype and CD8+ T lymphocytes as potential tools to predict local tumor outgrowth at the intervention site in malignant pleural mesothelioma

OBJECTIVES

In patients with malignant pleural mesothelioma (MPM), local tumor outgrowth (LTO) after invasive procedures is a well-known complication. Currently, no biomarker is available to predict the occurrence of LTO. This study aims to investigate whether the tumor macrophage infiltration and phenotype of and/or the infiltration of CD8+ T-cells predicts LTO.

MATERIALS AND METHODS

Ten mesothelioma patients who developed LTO were clinically and pathologically matched with 10 non-LTO mesothelioma patients. Immunohistochemistry was performed on diagnostic biopsies to determine the total TAM (CD68), the M2 TAM (CD163) and CD8+ T-cell count (CD8).

RESULTS

The mean M2/total TAM ratio differed between the two groups: 0.90±0.09 in the LTO group versus 0.63±0.09 in patients without LTO (p<0.001). In addition, the mean CD8+ T-cell count was significantly different between the two groups: 30 per 0.025 cm2 (range 2-60) in the LTO group and 140 per 0.025 cm2 (range 23-314) in the patients without LTO (p<0.01).

CONCLUSION

This study shows that patients who develop LTO after a local intervention have a higher M2/total TAM ratio and lower CD8+ cell count at diagnosis compared to patients who did not develop this outgrowth. We propose that the M2/total TAM ratio and the CD8+ T-cell amount are potential tools to predict which MPM patients are prone to develop LTO.

Protocol for the surgical and large bore procedures in malignant pleural mesothelioma and radiotherapy trial (SMART Trial): an RCT evaluating whether prophylactic radiotherapy reduces the incidence of procedure tract metastases

INTRODUCTION

Patients with malignant pleural mesothelioma (MPM) may develop painful 'procedure tract metastasis' (PTM) at the site of previous pleural interventions. Prophylactic radiotherapy has been used to minimise this complication; however, three small randomised trials have shown conflicting results regarding its effectiveness. The surgical and large bore procedures in malignant pleural mesothelioma and radiotherapy trial (SMART Trial) is a suitably powered, multicentre, randomised controlled trial, designed to evaluate the efficacy of prophylactic radiotherapy within 42 days of pleural instrumentation in preventing the development of PTM in MPM.

METHODS AND ANALYSIS

203 patients with a histocytologically proven diagnosis of MPM, who have undergone a large bore pleural intervention (thoracic surgery, large bore chest drain, indwelling pleural catheter or local anaesthetic thoracoscopy) in the previous 35 days, will be recruited from UK hospitals. Patients will be randomised (1:1) to receive immediate radiotherapy (21 Gy in 3 fractions over 3 working days within 42 days of the pleural intervention) or deferred radiotherapy (21 Gy in 3 fractions over 3 working days given if a PTM develops). Patients will be followed up for 12 months. The primary outcome measure is the rate of PTM until death or 12 months (whichever is sooner), as defined by the presence of a clinically palpable nodule of at least 1 cm diameter felt within 7 cm of the margins of the procedure site as confirmed by two assessors. Secondary outcome measures include chest pain, quality of life, analgaesic requirements, healthcare utilisation and safety (including radiotherapy toxicity).

ETHICS AND DISSEMINATION

The trial has received ethical approval from the Southampton B Research Ethics Committee (11/SC/0408). There is a Trial Steering Committee, including independent members and a patient and public representative. The trial results will be published in a peer-reviewed journal and presented at international conferences.

TRIAL REGISTRATION NUMBER

ISRCTN72767336.