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

Malignant pleural mesothelioma: current concepts in treatment

Malignant pleural mesothelioma (MPM) is a primary and locally aggressive tumor of the pleura. A well defined causal relationship with asbestos exposure, and an overwhelming media interest in the use of asbestos in industrialized countries after World War II, has produced a high level of awareness of this disease. With a peak incidence of MPM expected in Europe, Australia, and the US within the next 15 years, and the failure of current treatment approaches to offer long-term survival and improve quality of life, new therapeutic regimens are warranted. The effects of surgery in terms of survival and symptomatic relief have yet to be defined because of a lack of randomized trials. The role of radiotherapy in the treatment of MPM remains controversial, as the radiosensitivity of malignant mesothelial cells is modest. MPM response to chemotherapy is comparatively poor. The combination of pemetrexed and cisplatin chemotherapy has achieved the best objective responses. Presently, a multimodal approach is considered to be the cornerstone of treatment of MPM. Important ongoing international and national trials are addressing the roles of chemotherapy (e.g. the EAP and MS01 trial), radical surgery (e.g. the MARS trial) and radiotherapy (e.g. the SAKK group phase III study).

Multicenter trial of neo-adjuvant chemotherapy followed by extrapleural pneumonectomy in malignant pleural mesothelioma

BACKGROUND

The aim of this multicenter trial was to prospectively evaluate neo-adjuvant chemotherapy followed by extrapleural pneumonectomy (EPP) and radiotherapy, including quality of life as outcome.

PATIENTS AND METHODS

Eligible patients had malignant pleural mesothelioma of all histological types, World Health Organization performance status of zero to two and clinical stage T1-T3, N0-2, M0 disease considered completely resectable. Neo-adjuvant chemotherapy consisted of three cycles of cisplatin and gemcitabine followed by EPP. Postoperative radiotherapy was considered for all patients.

RESULTS

In all, 58 of 61 patients completed three cycles of neo-adjuvant chemotherapy. Forty-five patients (74%) underwent EPP and in 37 patients (61%) the resection was complete. Postoperative radiotherapy was initiated in 36 patients. The median survival of all patients was 19.8 months [95% confidence interval (CI) 14.6-24.5]. For the 45 patients undergoing EPP, the median survival was 23 months (95% CI 16.6-32.9). Psychological distress showed minor variations over time with distress above the cut-off score indicating no morbidity with 82% (N = 36) at baseline and 76% (N = 26) at 3 months after surgery (P = 0.5).

CONCLUSIONS

The observed rate of operability is promising. A median survival of 23 months for patients undergoing EPP compares favourably with the survival reported from single center studies of upfront surgery. This approach was not associated with an increase in psychological distress.

The role of radiotherapy in the treatment of malignant pleural mesothelioma

Radiation therapy for the treatment of malignant pleural mesothelioma has historically been limited by its efficacy. However, the increasing incidence of this tumour and the emergence of new technologies present a number of opportunities and challenges for this treatment modality. Radiotherapy is used to palliate mesothelioma patients with chest wall pain. Responses of over 60% have been seen, although the duration of response is often disappointing. The optimum dose has not been shown and many of the previous studies were small retrospective studies. An improved response has been seen in several studies where hyperthermia was added to radiotherapy. However, further investigation of this technique, which is not widely available, is required. There has not been any comparison of radiotherapy with chemotherapy in the palliation of patients with malignant pleural mesothelioma. Prophylactic chest wall radiotherapy to intervention sites successfully reduces the incidence of malignant seeding along the intervention tracts. However, the optimum dose and timing of treatment are not clear. There is no role for radical radiotherapy alone, but the role of radiotherapy as part of multimodality therapy is discussed. There have been studies of intensity-modulated radiotherapy as part of multimodality therapy and this technique needs to be evaluated further.

Radiotherapy for malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma is a relatively uncommon disease, but the incidence is increasing and is expected to peak in many developed countries in the next two decades. The management of patients with malignant mesothelioma is controversial. Very few patients are suitable for any potentially curative treatment and the effectiveness of radical therapy with surgery, radiotherapy and/or chemotherapy in curing patients or prolonging survival is uncertain. The role of radiotherapy is controversial although it has been used as part of multimodal therapy. The present review will try to clarify these uncertainties.

OBJECTIVES

To assess the effectiveness and safety of radiotherapy on patients with malignant pleural mesothelioma in any stage of the disease.

SEARCH STRATEGY

Both electronic and handsearches were conducted. All randomised controlled clinical trials were searched in electronic databases such as: Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE. Handsearching was aimed at the identification of evidence by reviewing journals not indexed in databases, proceedings of conferences and/or scientific meetings.

SELECTION CRITERIA

All randomised controlled clinical trials using radiotherapy for malignant pleural mesothelioma in any stage, alone or combined with other therapies in patients of either sex and any age, were included. Studies without a control group were excluded.

DATA COLLECTION AND ANALYSIS

There were no studies that fulfilled the inclusion criteria.

MAIN RESULTS

To date we have not found any reports of randomised comparisons of radiotherapy alone or combined for patients with malignant pleural mesothelioma.

AUTHORS' CONCLUSIONS

As radiotherapy has never been compared to chemotherapy or surgery or to best supportive care (as part of combination therapy) in a prospective, randomised trial, no data exist supporting one or the other treatment as a better option for patients with malignant pleural mesothelioma. There is a need for multicentre controlled randomised trials assessing the role of radiotherapy in the radical treatment of malignant pleural mesothelioma. The studies should be limited to patients with malignant pleural mesothelioma, classified by stage, cytology and type of radiotherapy. The type of radiotherapy should be defined in advance and variables of radiotherapy dose definition and delivery should be carefully controlled.

The role of radiation therapy in malignant pleural mesothelioma: a systematic review

INTRODUCTION

Radiation therapy may offer patients presenting with malignant pleural mesothelioma (MPM) symptom palliation and improvements in quality of life. This systematic review will address the role of radiation therapy in the management of MPM.

METHODS

A thorough systematic search of the literature was conducted for published articles and conference proceedings for applicable abstracts. Relevant trials were selected and assessed.

RESULTS

Three small randomized controlled trials compared prophylactic external beam radiation therapy to no radiation therapy for patients with thoracic tracts caused by drainage tubes or diagnostic procedures. None of those trials reported any serious adverse effects. A pooled analysis found no significant reduction in the frequency of procedure tract metastases. Four non-comparative studies have shown that hemithoracic irradiation alone resulted in significant toxicity, including radiation-induced pulmonary fibrosis, radiation pneumonitis, and bronchopleural fistula, without any survival benefit. Few of the identified studies reported on symptom control, and no studies included formal measures of quality of life.

CONCLUSION

There is limited evidence for the role of radiotherapy in the management of patients with MPM. Future studies including radiotherapy for the treatment of such patients should include formal measures of quality of life and symptom control.

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.

The Role of Radiation Therapy in Thoracic Tumors

Radiation plays an important role in the treatment of thoracic tumors. During the last 10 years there have been several major advances in thoracic RT including the incorporation of concurrent chemotherapy and the application of con-formal radiation-delivery techniques (eg, stereotactic RT, three-dimensional conformal RT, and intensity-modulated RT) that allow radiation dose escalation. Radiation as a local measure remains the definitive treatment of medically inoperable or surgically unresectable disease in NSCLC and part of a multimodality regimen for locally advanced NSCLC, limited stage SCLC, esophageal cancer, thymoma, and mesothelioma.

Management of malignant pleural effusions

PURPOSE OF REVIEW

Although malignant pleural effusions are a common medical problem, research into their optimal management remains sparse. The aim of this review is to summarise recent developments in this area.

RECENT FINDINGS

Talc remains the most efficacious pleurodesis agent. However, concerns remain about its side effect profile, with a number of cases of acute respiratory distress syndrome documented in the literature. A recent trial showed that using calibrated talc particles reduced the risk of morbidity from this procedure. Work on novel pleurodesis agents, such as transforming growth factor-beta, appears to induce pleurodesis in animal models without any unwanted side effects. This is a promising development and human trials are awaited. With regard to mesothelioma, recent chemotherapy trials with pemetrexed/cisplatin and raltitrexed/cisplatin are encouraging and appear, for the first time, to offer a small but real survival advantage.

SUMMARY

In the authors' opinion, the major developments in the management of malignant effusions during the past year are the development of safer pleurodesis agents and the promise of better combination chemotherapy agents for the treatment of mesothelioma.

Advances in the diagnosis, evaluation, and management of malignant pleural mesothelioma

Malignant mesothelioma is an insidious neoplasm arising from the mesothelial surfaces of the pleural and peritoneal cavities, the pericardium, or the tunica vaginalis. A total of 80% of all cases are pleural in origin. The predominant cause of malignant mesothelioma is inhalational exposure to asbestos, although evidence is increasing to support the hypothesis that simian virus-40 virus plays a role in cocarcinogenesis. Immunohistochemical markers such as calretinin, WT-1, and cytokeratin 5/6 are becoming established diagnostic markers. Preliminary data suggests that a soluble form of mesothelin could serve as a serum marker for established and early cases of mesothelioma. Positron emission tomography with 18-fluorodeoxyglucose in conjunction with computed tomograhy scanning has improved preoperative imaging and staging. Prognostic factors have been identified and verified. Negative indicators include thrombocytosis, high leukocyte counts, poor performance status, and nonepithelial histology. For the first time, there is now evidence that some treatments are increasing the quality and quantity of life for patients with mesothelioma. Chemotherapy, with the new multi-targeted antifolate drug Pemetrexed, combined with cisplatin, has shown superior survival rates in a large phase III trial when compared to cisplatin alone. High-dose intensity-modulated radiotherapy when administered after extrapleural pneumonectomy has resulted in excellent local control. Multimodality treatment programs that combine surgical cytoreduction with novel forms of radiation therapy and more effective chemotherapy combinations may offer significant increases in survival for certain subgroups of mesothelioma patients. Innovative palliative approaches have proved successful in alleviation of the significant symptoms experienced by many mesothelioma patients. Experimental treatments such as immunotherapy and gene therapy present a window of hope for all mesothelioma patients, and in the future, may be combined with 'standard therapy' in multimodality protocols. Patients with adequate performance status should be enrolled into clinical trials where possible. Over the past decade, significant advances have been made on several fronts that have improved the ability to diagnose a stage, define prognosis, and treat malignant pleural mesothelioma.

Pleural mesothelioma: little evidence, still time to do trials

CONTEXT

The incidence of malignant pleural mesothelioma is increasing throughout most of the world. This cancer is uniformly fatal, and characterised by progressive breathlessness and unremitting pain in the chest wall. From the onset of symptoms, survival is from a few weeks to a few years. Desperation by patients and doctors has driven a search for effective treatments. Clinical benefits are marginal and evidence of a good quality is lamentably lacking.

STARTING POINT

David Sugarbaker is the world's leading proponent of extrapleural pneumonectomy (EPP), an operation in which all the pleura is removed with the lung, pericardium, and diaphragm. He has recently reported the complications of this radical surgery in a series of 496 operations (J Thorac Cardiovasc Surg 2004; 128: 138-46). Although EPP as part of trimodality therapy (preoperative chemotherapy and postoperative radiation) is thought to be the best that can be offered and is regarded as the standard of care for selected patients given the morbidity associated with it, evidence for benefit is needed to justify its wider use. WHERE NEXT? With the increase in the number of cases there is increasing awareness of the disease, leading to earlier diagnosis, and an expectation that something must be done. Survival is short and the treatments on offer are onerous. The only responsible approach from a scientific, compassionate, or economic view (and why not combine all three?) is to find evidence of effectiveness to avoid futile and distressing treatment when possible.