What is the role of radiotherapy in malignant pleural mesothelioma?

Contemporary management of mesothelioma

Pleural mesothelioma (PM) is an aggressive asbestos-associated thoracic malignancy with a median survival of 12-18 months. Due to continued asbestos use in many nations, global incidence is rising. Causes due to non-occupational, environmental exposure are also rising in many countries despite utilisation bans. For many years, platinum--pemetrexed chemotherapy was the solitary licensed therapy, but first-line combination immune checkpoint blockade has recently demonstrated improved outcomes, with both regimes tested in predominantly late-stage cohorts. In the second-line setting, single-agent nivolumab has been shown to extend survival and is now available for routine use in some regions, while second-line chemotherapy has no proven role and opportunities for clinical trials should be maximised in relapsed disease. Surgery for "technically resectable" disease has been offered for decades in many expert centres, but the recent results from the phase III MARS2 trial have challenged this approach. There remains no robustly proven standard of care for early-stage PM. The clinical trial landscape for PM is complex and increasingly diverse, making further development of specialist PM multidisciplinary teams an important priority in all countries. The observation of improving outcomes in centres that have adopted this service model emphasises the importance of high-quality diagnostics and equitable access to therapies and trials. Novel therapies targeting a range of aberrations are being evaluated; however, a better understanding of the molecular drivers and their associated vulnerabilities is required to identify and prioritise treatment targets.

Biological Pathways Associated With the Development of Pulmonary Toxicities in Mesothelioma Patients Treated With Radical Hemithoracic Radiation Therapy: A Preliminary Study

Radical hemithoracic radiotherapy (RHR), after lung-sparing surgery, has recently become a concrete therapeutic option for malignant pleural mesothelioma (MPM), an asbestos-related, highly aggressive tumor with increasing incidence and poor prognosis. Although the toxicity associated to this treatment has been reduced, it is still not negligible and must be considered when treating patients. Genetic factors appear to play a role determining radiotherapy toxicity. The aim of this study is the identification of biological pathways, retrieved through whole exome sequencing (WES), possibly associated to the development of lung adverse effects in MPM patients treated with RHR. The study included individuals with MPM, treated with lung-sparing surgery and chemotherapy, followed by RHR with curative intent, and followed up prospectively for development of pulmonary toxicity. Due to the strong impact of grade 3 pulmonary toxicities on the quality of life, compared with less serious adverse events, for genetic analyses, patients were divided into a none or tolerable pulmonary toxicity (NoSTox) group (grade ≤2) and a severe pulmonary toxicity (STox) group (grade = 3). Variant enrichment analysis allowed us to identify different pathway signatures characterizing NoSTox and Stox patients, allowing to formulate hypotheses on the protection from side effects derived from radiotherapy as well as factors predisposing to a worst response to the treatment. Our findings, being aware of the small number of patients analyzed, could be considered a starting point for the definition of a panel of pathways, possibly helpful in the management of MPM patients.

Multi-institutional survey of malignant pleural mesothelioma patients in the Hokushin region

BACKGROUND

Malignant pleural mesothelioma (MPM) is a major occupational and environmental neoplasm. The purpose of this study was to validate the clinical and epidemiological factors, diagnosis, and initial treatment among MPM patients in the Hokushin region.

METHODS

We surveyed retrospective data from 152,921 cancer patients in 22 principal hospitals.

RESULTS

A total of 166 MPM cases were newly diagnosed. These patients consisted of 136 men and 30 women, with a median age of 69 years. We estimated the incidence rate for MPM to be 0.55 cases per 100,000 person-years in this study. The ratio per 100,000 population-years was 0.39 in Fukui, 0.60 in Ishikawa, 1.02 in Toyama and 0.35 in Nagano. Forty-five patients were discovered when diagnosed incidentally in patients under observations for other diseases. Forty-six cases were diagnosed as localized disease, while 13 had accompanying regional lymph node metastasis. Furthermore, 44 cases showed infiltration into adjacent organs. A histo-cytological diagnosis was made in 164 cases (98.8%). A surgical approach, chemotherapy, and radiotherapy were performed for 33, 88, and 6 patients, respectively, while 44 patients (26.5%) received best supportive care. Multimodality therapy was conducted in just 3.0% of the MPM patients CONCLUSION: MPM has a tragically rapid progression if discovered under observations for other diseases. Workers in health-related fields should be on high alert for aggressive MPM. Better evaluation and multi-disciplinary approaches to MPM in these regions are needed to optimize multimodality therapy.

The minimum standard of care for managing malignant pleural mesothelioma in developing nations within the Asia-Pacific Region

Malignant pleural mesothelioma (MPM) is an incurable malignancy associated with high symptom burden and poor prognosis. The relationship between asbestos exposure and MPM incidence is well-established. The incidence rate of MPM in Australia and New Zealand is among the highest globally. Matching the experience of other nations with legal restrictions on asbestos, incidence is expected to fall. In contrast, the incidence of MPM is rising in the developing nations of the Asia-Pacific as consumption and mining (albeit to a lesser extent) of asbestos continues. The incidence of MPM in these nations is currently low or unknown, reflecting insufficient latency periods since industrial use of asbestos, deficient resources for accurate diagnosis, and lack of occupational disease or cancer registries. The landscape of treatment for MPM is rapidly changing with combination immunotherapy now demonstrating improved survival in the first-line setting. Considering vast global inequity in access to anticancer treatments, establishing minimum standard of care for MPM in developing nations is of greater significance. Here, we review the evidence that form the basis of our minimum-standard recommendations for diagnosis, systemic treatment, management of recurrent pleural effusions, and symptom management. We also briefly review evidence-based treatment that may be considered for those with access.

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.

Trimodality Treatment of Malignant Pleural Mesothelioma: An Institutional Review

OBJECTIVE

Malignant pleural mesothelioma (MPM) is a deadly disease with varying treatment options. This study retrospectively describes treatment practices at the University of Washington Medical System from 1980 to 2011, and evaluates the impact of trimodality therapy and radiation (photon and neutron) on survival.

METHODS

A retrospective study was conducted on patients treated for MPM. Univariate and multivariate methods were utilized to evaluate potential factors associated with survival. Treatments received and baseline characteristics were included. Survival analysis of trimodality therapy was performed using a propensity score method to control for baseline characteristics.

RESULTS

Among 78 eligible patients, the median age at diagnosis was 59 years and the median survival was 13.7 months. On multivariate analysis, the significant predictors of improved survival were age, smoking history, location, and receipt of radiation therapy or chemotherapy. In the 48 patients receiving radiation therapy, the difference in survival between neutron therapy and non-neutron therapy patients was not statistically significant: hazard ratio, 1.20 (95% confidence interval, 0.68-2.13), P=0.52. Patients receiving trimodality therapy were more likely to have early-stage disease (60% vs. 30%) and epithelioid histology (86% vs. 58%). In a propensity score-weighted Cox proportional hazards model, trimodality therapy patients had improved overall survival, hazard ratio 0.45, P=0.004, median 14.6 versus 8.6 months.

CONCLUSIONS

Trimodality therapy was significantly associated with prolonged survival in patients with MPM, even when adjusting for baseline patient factors. Radiation therapy was associated with improved survival, but the modality of radiation therapy used was not associated with outcome.

Intensity-modulated radiotherapy for relapsed malignant pleural mesothelioma

The use of novel radiotherapy techniques is widely increasing, allowing clinicians to treat diseases that were previously difficult to treat with radiation therapy. Malignant pleural mesothelioma is a clear example of this clinical challenge. We describe our first experience with intensity-modulated radiotherapy technique which was used to treat a 73-year-old patient with multiple relapsing malignant pleural mesothelioma. Intensity-modulated radiation therapy has allowed to respect the QUANTEC (quantitative analyses of normal tissue effects in the clinic) dose constraints, patient has experienced a 14 months progression-free time, without relevant subacute or late lung toxicity.

Management of recurrence after initial surgery for malignant pleural mesothelioma: a mini-review

Recurrence after surgery in the multimodality therapy for malignant pleural mesothelioma is a common problem. As the majority of patients experience not only local but also distant metastases, a systemic treatment strategy in addition to local control measures remains necessary. Nevertheless, none of the chemotherapy regimens have achieved clinical success. Local management modalities such as stereotaxic treatments, cryoablation and redo surgery on the other hand have promising results, but provide palliative outcomes.

Reactive oxygen species a double-edged sword for mesothelioma

It is well known that oxidative stress can lead to chronic inflammation which, in turn, could mediate most chronic diseases including cancer. Oxidants have been implicated in the activity of crocidolite and amosite, the most powerful types of asbestos associated to the occurrence of mesothelioma. Currently rates of mesothelioma are rising and estimates indicate that the incidence of mesothelioma will peak within the next 10-15 years in the western world, while in Japan the peak is predicted not to occur until 40 years from now. Although the use of asbestos has been banned in many countries around the world, production of and the potentially hazardous exposure to asbestos is still present with locally high incidences of mesothelioma. Today a new man-made material, carbon nanotubes, has arisen as a concern; carbon nanotubes may display 'asbestos-like' pathogenicity with mesothelioma induction potential. Carbon nanotubes resulted in the greatest reactive oxygen species generation. How oxidative stress activates inflammatory pathways leading to the transformation of a normal cell to a tumor cell, to tumor cell survival, proliferation, invasion, angiogenesis, chemoresistance, and radioresistance, is the aim of this review.

Is Radiotherapy Useful for Treating Pain in Mesothelioma?: A Phase II Trial

INTRODUCTION

Radiotherapy is often used to treat pain in malignant pleural mesothelioma (MPM), although there is limited evidence to support this. The aim of this trial was to assess the role of radiotherapy for the treatment of pain in MPM.

METHODS

A multicentre, single arm phase II trial was conducted. Eligible patients fulfilled the following criteria: pathological or radiological diagnosis of MPM; pain secondary to MPM; radiotherapy indicated for pain control; and more than 18 years of age. Patients had assessments of pain and other symptoms at baseline and then received 20 Gy in five daily fractions. Key follow-up points were 5 and 12 weeks posttreatment. The primary end point measure was assessment of pain at the site of radiotherapy at 5 weeks. Secondary end points included effects on quality of life, breathlessness, fatigue, mood, toxicity, and the radiological response.

RESULTS

Forty patients were recruited from three UK oncology centers. Fourteen patients had a clinically meaningful improvement in their pain 5 weeks post radiotherapy (intention to treat), with five patients having a complete improvement. On the basis of a complete case analysis of the 30 patients assessable at week 5, 47% (confidence intervals, 28.3-65.7) of patients alive at week 5 had an improvement in their pain. There was no improvement in other key symptoms or quality of life.

CONCLUSIONS

Radiotherapy for pain control in MPM is an effective treatment in a proportion of patients. Future studies examining differing radiotherapy regimens with a view to improving response rates are warranted.

Demographics, management and survival of patients with malignant pleural mesothelioma in the National Lung Cancer Audit in England and Wales

INTRODUCTION AND METHODS

Malignant pleural mesothelioma (MPM) is an uncommon cancer with poor survival. We have used data collected for the UK National Lung Cancer Audit to assess current practice and to highlight regional variation in the management of mesothelioma patients, as well as to describe survival patterns in subgroups.

RESULTS

Our data on 8740 cases seen in hospitals in England and Wales is the largest cohort of MPM in the literature and represents approximately 80% of the total incident cases. 83% are male and median age is 73 years. Performance status is recorded in 81% and of these approximately 70% are PS 0-2. Stage is poorly recorded and unreliable in this dataset. The patient pathway is similar to lung cancer with approximately one-fifth having a non-elective referral to secondary care. A histo-cytological diagnosis is made in 87% and varies across organisations. Only 67% have anti-cancer treatment, and this also varies across organisations, but there has been an annual increase in the proportion receiving chemotherapy. Overall median survival was 9.5 months, with a 1YS of 41.4% and 3YS of 12.0%, but was strongly linked to performance status and histological subtype. Median survival also varied by cancer network from 209 days to 349 days, but appeared to increase from of 9.2 months in 2008 to 10.5 months in 2012.

CONCLUSION

Our data provide a large scale, detailed assessment of MPM epidemiology, treatment choices and outcomes. Incidence is increasing in line with predictions and uptake of treatments has generally mirrored publication of key MPM treatment trials, in particular increasing use of chemotherapy but low uptake of radical surgery. However, there is significant variation in care patterns and outcomes that may reflect limited expertise in area with low incidence. Initiatives to improve outcomes should include improved recording of clinical stage.

Diagnosis and treatment of malignant pleural mesothelioma

There are three major challenges in the diagnosis of malignant pleural mesothelioma: mesothelioma must be distinguished from benign mesothelial hyperplasia; malignant mesothelioma (and its subtypes) must be distinguished from metastatic carcinoma; and invasion of structures adjacent to the pleura must be demonstrated. The basis for clarifying the first two aspects is determination of a panel of monoclonal antibodies with appropriate immunohistochemical evaluation performed by highly qualified experts. Clarification of the third aspect requires sufficiently abundant, deep biopsy material, for which thoracoscopy is the technique of choice. Video-assisted needle biopsy with real-time imaging can be of great assistance when there is diffuse nodal thickening and scant or absent effusion. Given the difficulties of reaching an early diagnosis, cure is not generally achieved with radical surgery (pleuropneumonectomy), so liberation of the tumor mass with pleurectomy/decortication combined with chemo- or radiation therapy (multimodal treatment) has been gaining followers in recent years. In cases in which surgery is not feasible, chemotherapy (a combination of pemetrexed and platinum-derived compounds, in most cases) with pleurodesis or a tunneled pleural drainage catheter, if control of pleural effusion is required, can be considered. Radiation therapy is reserved for treatment of pain associated with infiltration of the chest wall or any other neighboring structure. In any case, comprehensive support treatment for pain control in specialist units is essential: this acquires particular significance in this type of malignancy.

Surgical management of malignant pleural mesothelioma: impact of surgery on survival and quality of life-relation to chemotherapy, radiotherapy, and alternative therapies

Introduction. Malignant pleural mesothelioma (MPM) is an aggressive cancer arising from pleural mesothelium. Surgery aims to either cure the disease or control the symptoms. Two surgical procedures exist: extrapleural pneumonectomy (EPP) and pleurectomy/decortication (P/D). In this systematic review we assess current evidence on safety and efficacy of surgery. Methods. Five electronic databases were reviewed from January 1990 to January 2013. Studies were selected according to a predefined protocol. Primary endpoint was overall survival. Secondary endpoints included quality of life, disease-free survival, disease recurrence, morbidity, and length of hospital stay. Results. Sixteen studies were included. Median survival ranged from 8.1 to 32 months for P/D and from 6.9 to 46.9 months for EPP. Perioperative mortality was 0%–9.8% and 3.2%–12.5%, respectively. Perioperative morbidity was 5.9%–55% for P/D and 10%–82.6% for EPP. Average length of stay was 7 days for P/D and 9 days for EPP. Conclusion. Current evidence cannot definitively answer which procedure (EPP or P/D) is more beneficial in terms of survival and operative risks. This systematic review suggests that surgery in the context of trimodality therapy offers acceptable perioperative outcomes and long-term survival. Centres specialising in MPM management have better results.

Radiotherapy for the treatment of pain in malignant pleural mesothelioma: a systematic review

Radiotherapy is commonly used to treat pain in malignant pleural mesothelioma (MPM). The purpose of this systematic review is to examine the evidence for this practice. Medline (1946-2013), Embase (1974-2013) and Central (The Cochrane Library Issue 9, 2012) databases were searched. Eligible studies met the following criteria: MPM (histological or radiological diagnosis), radiotherapy given with the intent of improving pain, response rates to radiotherapy reported, dose and fractionation reported and the relationship between radiotherapy and pain response explored. All studies had independent review and were graded according to evidence level. Eight studies met the eligibility criteria. Two studies were prospective single arm phase II studies while the remainder were retrospective case series. All were graded as either Level 2 or Level 3 evidence. Due to marked heterogeneity among studies, quantitative synthesis of results was not possible. No high quality evidence currently exists to support radiotherapy in treating pain in MPM. Studies focusing on clear pain endpoints and improving target delineation are needed. Such studies should also use modern radiotherapy techniques and concentrate on dose escalation.

Advances in the management of pleural disease

Pleural disease affects over 3000 people per million population annually. Consequently, it represents a significant proportion of the respiratory physician's workload and can present to clinicians of all backgrounds in primary and secondary care. Pleural effusions have been reported in association with over 50 different conditions; some related to specific pulmonary pathologies, but many being manifestations of multisystem disease. The burden that conditions such as pleural infection; malignant pleural disease; and pneumothorax impose on patients and health care systems is enormous and growing. As such, a clear understanding of these key conditions is crucial to any physician regardless of the specialty. This article addresses a number of areas relating to pleural disease, providing an overview of the diagnostic and therapeutic advances that have been made in our understanding of pleural pathology in recent years. The directions that future research in this important area of respiratory medicine might take will also be discussed.

Clinical indications and results after chest wall resection for recurrent mesothelioma

OBJECTIVE

The ipsilateral hemithorax is the most common site of recurrence after surgical resection for malignant pleural mesothelioma. Salvage treatment has generally been ineffective. We reviewed the outcomes after resection of isolated ipsilateral chest recurrence after cytoreductive surgery in patients with malignant pleural mesothelioma.

METHODS

Patients with malignant pleural mesothelioma who underwent initial surgical resection at our institution from 1988 to 2011 and were subsequently treated for localized recurrence with an additional chest resection were identified and their data retrospectively reviewed.

RESULTS

A total of 1142 patients underwent either extrapleural pneumonectomy (n = 794) or pleurectomy/decortication (n = 348). Of the patients who returned for follow-up, 47 (4.1%) had chest wall recurrence amenable to resection. The location of recurrence was predominantly incisional (49%) and/or costophrenic (38%). The median time to recurrence after either extrapleural pneumonectomy or pleurectomy/decortication was 16.1 months (range, 2.7-58.2). No 30-day mortality was found for chest wall resection, and the median length of stay in the hospital was 3 days (range, 0-12). The median overall survival duration after chest wall resection correlated positively with the time to recurrence (epithelial: median, 8.9, 17.2, and 35.8 months for a time to recurrence of <12, 12 to <24, and ≥24 months, respectively; biphasic: median, 2.7 and 15.9 months for a time to recurrence of <10 and ≥10 months, respectively).

CONCLUSIONS

Chest wall resection is a safe and effective therapeutic option in the management of localized chest wall recurrence of malignant pleural mesothelioma. The time to recurrence appears to be predictive of the expected survival benefit in both epithelial and biphasic malignant pleural mesothelioma.

Role of new radiation techniques in the treatment of pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm arising from the surface serosal cells of the pleural cavity. Surgery remains the main therapeutic standard in the treatment of MPM with the goal of complete gross cytoreduction of the tumor. Because MPM is a diffuse disease affecting the entire mesothelial lining of the hemithorax, surgery alone can rarely achieve adequate tumor-free resection margins. The surgical choices are pleurectomy/decortication (P/D) or extrapleural pneumonectomy (EPP). Radiotherapy (RT) is usually applied postoperatively with the aim to improve local control. However, the efficacy of RT is limited by the large volume of the target to be irradiated (tumor and pleural cavity) and the radiosensitivity of the nearby organs (heart, liver, lung, spinal cord, and esophagus). These factors have historically limited the effective radiation doses that can be given to the patient. There is no role for radical RT alone, but the role of RT as part of multimodality therapy is discussed. After EPP adjuvant RT to the entire hemithorax can reduce the recurrence rate and is well tolerated if strict limits to the dose to contralateral lung are applied: the V20 and V5 (the percent volume of the lung receiving more than 20Gy and 5Gy of radiation) correlate with increased lung toxicity. The use of modern sophisticated techniques allows good target coverage, more conformal high dose delivery, and clinically relevant normal tissue sparing.

Multimodal therapy of malignant pleural mesothelioma: is the replacement of radical surgery imminent?

OBJECTIVES

Malignant pleural mesothelioma (MPM) remains an aggressive thoracic malignancy associated with poor prognosis. There is no standard treatment regimen, and particularly, the impact of radical surgery remains controversial. The main goal of our retrospective single-centre study was to evaluate the surgical and non-surgical treatment modalities applied at our division regarding their effect on the patient's survival.

METHODS

During the last decade, 82 patients with histologically confirmed MPM were treated at our division. The complete clinical records of 61 patients were eligible for statistical evaluation.

RESULTS

There were 14 women (23%) and 47 men (77%) with a mean age of 63.7 years. Epitheloid subtype was found in 48 patients (78.7%), sarcomatoid in 3 (4.9%) and biphasic in 10 (16%). Surgery as the first treatment modality was performed in 44 patients (72.1%). Pleurectomy/decortication was done in 28 cases (45.9%), extended pleurectomy/decortication was performed in 13 (21.3%) and extrapleural pneumonectomy in 3 (4.9%). Additional intraoperative photodynamic therapy was administered in 20 patients, 34 underwent chemotherapy (55.7%) and 12 had radiotherapy (19.7%). Mean survival time for the collective was 18.3 months. Five-year survival was 17% in the epitheloid histology group, where patients treated with chemotherapy alone yielded a significant increase in survival (P = 0.049), and those with other subtypes survived for a maximum of 20.6 months.

CONCLUSIONS

Chemotherapy and pleurectomy/decortication can extend the survival time of patients with MPM remarkably. The adequate treatment options have to be tailored to the specific particular needs of each patient considering histological subtype, tumour stage and patient's individual functional assessment as well as comorbidity.