Multimodality treatment programs for malignant pleural mesothelioma using high-dose hemithorax irradiation

Plasma-activated medium as adjuvant therapy for lung cancer with malignant pleural effusion

This study compared effects of plasma-activated medium (PAM) with effects of conventional clinical thermal therapy on both lung cancer cells and benign cells for management of malignant pleural effusion (MPE). For MPE treatment, chemotherapy, photodynamic therapy, and thermal therapy are used but caused systemic side effects, patient photosensitivity, and edema, respectively. Recent studies show that plasma induces apoptosis in cancer cells with minor effects on normal cells and is cost-effective. However, the effects of plasma on MPE have not been investigated previously. This study applied a nonthermal atmospheric-pressure plasma jet to treat RPMI medium to produce PAM, carefully controlled the long-life reactive oxygen and nitrogen species concentration in PAM, and treated the cells. The influence of PAM treatment on the microenvironment of cells was also checked. The results indicated that PAM selectively inhibited CL1–5 and A549 cells, exerting minor effects on benign mesothelial and fibroblast cells. In contrast to selective lethal effects of PAM, thermal therapy inhibited both CL1–5 and benign mesothelial cells. This study also found that fibroblast growth factor 1 is not the factor explaining why PAM can selectively inhibit CL1–5 cells. These results indicate that PAM is potentially a less-harmful and cost-effective adjuvant therapy for MPE.

Volumetric Modulated Arc Therapy After Lung Sparing Surgery for Malignant Pleural Mesothelioma: A Single Institution Experience

INTRODUCTION

We investigated the possible role of volumetric modulated arc therapy (VMAT) in the setting of adjuvant treatment of malignant pleural mesothelioma (MPM) after lung-sparing surgery with pleurectomy and decortication.

MATERIALS AND METHODS

Patients affected by MPM who had undergone pleurectomy and decortication and adjuvant radiotherapy with VMAT were included. The endpoints of the present analysis were local control, progression-free survival, and overall survival. Assessment of the variables affecting survival was performed using univariate and multivariate Cox proportional hazard models.

RESULTS

A total of 49 patients were included in the present study. Of the 49 patients, 96% had been treated with a trimodality approach. Radiotherapy was delivered to a median dose of 44 Gy in 22 fractions (range, 22-59.4 Gy). The treatment was well tolerated, with just 2 grade 3 acute toxicities, 1 grade 5, and 2 grade 4 toxicities recorded during the follow-up period. The median follow-up period was 27.4 months. The local control rate at 12, 24, and 36 months was 75.2%, 67.4%, and 56.5%, respectively. The median progression-free survival was 14.9 months (95% confidence interval [CI], 7.5-25.2). The median overall survival was 21.5 months (95% CI, 15.3-37.1). On multivariate analysis, the administration of carboplatin- instead of cisplatin-based chemotherapy (hazard ratio, 2.97; 95% CI, 1.22-7.26; P = .017) and R2 resection (hazard ratio, 1.95; 95% CI, 1.27-2.99; P = .002) showed a negative correlation with overall survival. On univariate analysis, the percentage of the heart receiving >20 Gy and >30 was associated with the occurrence of late pneumonitis (P = .018 and P = .077).

CONCLUSION

VMAT is feasible in the setting of MPM after lung-sparing surgery. The toxicity rates were reduced with this technique compared with historical data of older techniques. Local and distant failure remain a major issue to be addressed in future trials.

The revised staging system for malignant pleural mesothelioma based on surveillance, epidemiology, and end results database

BACKGROUND

Several staging systems for MPM have been introduced. However, none of them provide perfect survival stratification among heterogeneous patients. The aim of this population-based cohort study was to propose adjustments to current staging system for malignant pleural mesothelioma (MPM).

METHODS

We retrieved MPM data from Surveillance, Epidemiology, and End Results database (1973-2014). Kaplan-Meier method was derived to examine the prognostic effects of tumor, lymph node, metastasis and histology features. Proportional hazards models guided adjustments to stage groupings. The accuracy of staging systems at predicting survival was evaluated by concordance index and bootstrap resampling.

RESULTS

A total of 1110 MPM cases were extracted from SEER. T stage failed to demonstrate survival difference between adjacent categories with the exception of T3 versus T4 (P < 0.001). Patients in M0 had better prognosis than those in M1 (P < 0.001). Exploratory analyses suggested important survival difference for single-versus multiple-site M1 cases (P < 0.001), but not for different metastatic sites (P = 0.286). Histology subtype was a significant prognostic indicator (P < 0.001). Regrouping of TNM and histology combinations resulted in the best concordance index (0.683), compared with UICC 2010 (0.578) and IASLC 2016 (0.585) staging systems. The revised staging system also improved patients distribution (IA:33.8%, IB:17.0%, II: 20.7%, IIIA:10.6%, IIIB: 6.8%, IV:11.1%). Log-rank analyses and calibration plots both demonstrated the new stage achieved optimal survival prediction and discrimination.

CONCLUSION

The revised staging system improved patients distribution and survival stratification for MPM.

Advances in systemic therapy for malignant mesothelioma: future perspectives

Malignant mesothelioma is a rare and aggressive form of cancer affecting the mesothelium. This mainly occupational disease is becoming more common in those countries where asbestos has been used for industrial applications. Notwithstanding the progress made in the field, patients do not survive more than 12 months on average with standard treatment. With the advent of next generation sequencing, it is now possible to study the mutational landscape of each tumor with the aim of identifying the genetic aberrations driving tumorigenesis. This review encompasses the latest research in the field, with particular attention to new chemotherapy combinatorial regimens, molecular targets and immunotherapies, providing a comprehensive picture of the current and future treatment options for malignant mesothelioma patients.

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.

Treatment of malignant pleural mesothelioma with carboplatin, liposomized doxorubicin, and gemcitabine: a phase II study

BACKGROUND

Malignant pleural mesothelioma has a poor prognosis and there is limited effect of treatment. The Nordic Mesothelioma groups decided in the year 2000 to investigate a combination of liposomized doxorubicin, carboplatin, and gemcitabine for this disease in a phase II study.

METHODS

From January 2001, to December 2003, 173 evaluable patients with biopsy-verified malignant mesothelioma were included. Two patients were lost to follow-up, but all the others were followed for at least 4 years or until death.

RESULTS

Toxicity was fairly low. There were 56 responses (32.4%), of which 2 were complete; the median time to progression was 8.6 months, and the median overall survival was 13 months. Some patients had their responses 4 to 6 months after last treatment. For 116 patients with epitheloid subtype, median survival was 17 months. A subgroup of these patients with good performance status, early stage, and age 70 years or less, showed a median survival of 22 months.

CONCLUSION

The treatment yields good results with a high number of responses and long survival, and a low toxicity. The long survival of the epitheloid subgroup with good prognostic factors is as good as or even better than some studies on "radical" surgery or multimodal treatment, underlining the need of randomized studies to evaluate such treatment options.

Multidisciplinary treatment of malignant pleural mesothelioma

The incidence of malignant pleural mesothelioma (MPM) is increasing worldwide, and is predicted to peak in the next 10-20 years. Difficulties in MPM diagnosis and staging, especially of early disease, have thwarted the development of a universally accepted therapeutic approach. Single modality therapies (surgery, radiotherapy, chemotherapy) have generally failed to significantly prolong patient survival. As a result, multimodality treatment regimens have been developed. Radical surgery with extrapleural pneumonectomy and adjuvant treatments has become the preferred option in early disease, but the benefits of such an aggressive approach have been questioned because of significant treatment-related morbidity and mortality. In the past few years, there have been several major advances in the management of patients with MPM, including more accurate staging and patient selection, improvements in surgical techniques and postoperative care, novel chemotherapy regimens with definite activity such as antifolate (pemetrexed or raltitrexed)-platinum combinations, and new radiotherapy techniques such as intensity-modulated radiation therapy. Induction chemotherapy followed by surgery and adjuvant radiotherapy has shown promising results. A number of molecular alterations occurring in MPM have been reported, providing broader insights into its biology and leading to the identification of new targets for therapy. However, currently available treatments still appear to have modest results. Further studies are needed to provide evidence-based recommendations for the treatment of early and advanced stages of this disease.

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.

Dynamic Contrast-Enhanced MRI of Malignant Pleural Mesothelioma

STUDY OBJECTIVE

Dynamic contrast-enhanced MRI (DCE-MRI) followed by pharmacokinetic analysis has been successfully used in a variety of solid tumors. The aims of this study were to evaluate the feasibility of DCE-MRI in malignant pleural mesothelioma (MPM), to differentiate benign from pathologic tissue and compare pharmacokinetic with clinical parameters and survival in order to map out its microcirculation; and to compare pharmacokinetic with clinical parameter and survival in order to improve our understanding of the in vivo biology of this malignancy.

METHODS

Nineteen patients with a diagnosis of MPM who were scheduled to receive chemotherapy with gemcitabine were enrolled in the study. DCE-MRI was performed before treatment (n = 19) and after the third cycle (n = 12) and sixth cycle (n = 7) of chemotherapy. An established pharmacokinetic two-compartment model was used to analyze DCE-MRI. Tumor regions were characterized by the pharmacokinetic parameters amplitude (Amp), redistribution rate constant (kep), and elimination rate constant (kel). Kinetic parameters of tumor tissue and normal tissue were compared using the Student t test. Patients were classified as clinical responders or nonresponders according to clinical outcome, and these groups were compared with the pharmacokinetic parameters derived from DCE-MRI.

RESULTS

Normal and tumor tissue could be distinguished by the pharmacokinetic parameters Amp and kel (p </= 0.001). Clinical responders had a median kep value within the tumor of 2.6 min, while nonresponders showed a higher value (3.6 min), which coincided with longer survival (780 days vs 460 days).

CONCLUSIONS

DCE-MRI can be used in patients with MPM to assess tumor microvascular properties and to demonstrate tumor heterogeneity for therapy monitoring. High pretherapeutic values of kep within the tumor correlated with a poor overall response to therapy.

Radiotherapy for mesothelioma

Three to four thousand cases of malignant pleural mesothelioma will occur in the United States this year. Single-modality therapy with radiation plays a role for palliation. Radiation can prevent tumor recurrence at drain/instrumentation sites and provide symptomatic relief of pain and other complaints. Combinations of surgery and radiation also have been attempted with curative intent. The best local control has been found--EPP followed by radiotherapy. Locoregional tumor recurrence can be dramatically reduced with combinations of extrapleural pneumonectomy and radiation therapy. Survival in aggressively treated early-stage patients is excellent. However, the preponderance of death from distant metastases makes the development of better systemic therapy essential. Better therapy also must be developed for patients who are not candidates for extrapleural pneumonectomy.

The radiologic measurement of mesothelioma

The radiologic evaluation of disease, which now includes the quantification of disease, has become an essential part of clinical medicine. The unique circumferential and often scalloped morphology of mesothelioma, however, distinguishes it from other thoracic neoplasms. The challenges of measuring mesothelioma are many. In this article, the authors explore the demands, the current standard of clinical practice, and the opportunities associated with the radiologic measurement of mesothelioma.

Phase II trial of pleural photodynamic therapy and surgery for patients with non-small-cell lung cancer with pleural spread

PURPOSE

Non-small-cell lung cancer (NSCLC) with pleural spread is incurable, with median survival rates ranging from 6 to 9 months. Surgery alone fails to locally control this disease or extend survival beyond the accepted treatment, palliative chemotherapy.

METHODS

We conducted a phase II trial to evaluate the effects on local control and survival of combining surgery with intraoperative photodynamic therapy (PDT), a light-based cancer treatment, in patients with NSCLC with pleural spread. Patients received porfimer sodium (2 mg/kg), 24 hours before surgery, at which time all gross tumor was resected and followed by illumination of the hemithorax with 630 nm light to a measured dose of 30 J/cm(2). Photosensitizer levels in tumor and surrounding normal tissue were measured.

RESULTS

Twenty-two patients with NSCLC were enrolled; 17 underwent complete debulking and PDT, three underwent partial debulking/PDT, and two patients were unresectable. Local control of pleural disease at 6 months was achieved in 11 of 15 (73.3%; 95% CI, 44.9% to 92.2%) assessable patients. Median overall survival for all 22 patients was 21.7 months (95% CI, 17.7 to 25.8 months). Measured levels of porfimer sodium in tumor were greater than those measured in normal tissues, with ratios ranging from 1.19 to 22.42.

CONCLUSION

Our results indicate surgery and PDT can be performed safely with very good local control. The median survival of 21.7 months, calculated from the time of surgery and PDT is encouraging. Further evaluation of this therapy is warranted.

Intensity-modulated photon arc therapy for treatment of pleural mesothelioma

Radiotherapy plays a key role in the definitive or adjuvant management of patients with mesothelioma of the pleural surface. Many patients are referred for radiation with intact lung following biopsy or subtotal pleurectomy. Delivery of efficacious doses of radiation to the pleural lining while avoiding lung parenchyma toxicity has been a difficult technical challenge. Using opposed photon fields produce doses in lung that result in moderate-to-severe pulmonary toxicity in 100% of patients treated. Combined photon-electron beam treatment, at total doses of 4250 cGy to the pleural surface, results in two-thirds of the lung volume receiving over 2100 cGy. We have developed a technique using intensity-modulated photon arc therapy (IMRT) that significantly improves the dose distribution to the pleural surface with concomitant decrease in dose to lung parenchyma compared to traditional techniques. IMRT treatment of the pleural lining consists of segments of photon arcs that can be intensity modulated with varying beam weights and multileaf positions to produce a more uniform distribution to the pleural surface, while at the same time reducing the overall dose to the lung itself. Computed tomography (CT) simulation is critical for precise identification of target volumes as well as critical normal structures (lung and heart). Rotational arc trajectories and individual leaf positions and weightings are then defined for each CT plane within the patient. This paper will describe the proposed rotational IMRT technique and, using simulated isodose distributions, show the improved potential for sparing of dose to the critical structures of the lung, heart, and spinal cord.

Surgical treatment of malignant pleural mesothelioma: a review

Despite many years of clinical research, there is still no effective therapy for malignant pleural mesothelioma (MPM). Untreated, the prognosis is poor, with a median survival of < 1 year. Single-agent or combination chemotherapy as well as radiotherapy have not shown persistent improvements in response or survival. In general, MPM is a disease confined to the pleural cavity for a long time before metastasizing. Therefore, focus on local treatment seems rational. Surgical resection has been considered the mainstay of treatment by some. However, surgery alone results in high recurrence rates, and the survival benefit remains questionable. In recent years, the emphasis has been on surgery combined with adjuvant therapies. In this article, the present state of surgical management of MPM will be reviewed.

Malignant mesothelioma: options for management

In the past, there has been a tendency to think of diffuse malignant pleural mesothelioma as one disease in therapeutic terms, regardless of histological type and tumor stage. This does not happen with other tumors, yet it is equally illogical and inappropriate in mesothelioma. As with other tumors, early diagnosis-while the disease is still in stage I, or even at an in situ stage-must be the goal so that therapy can be maximized, particularly if immunotherapy or gene therapy is to be used. Patients with pure epithelial mesothelioma have a better prognosis and respond better to trimodality therapy. Stage I patients who meet fitness criteria should be offered the option of radical surgery in combination with chemotherapy and radiotherapy. Further research is required to determine the optimum neoadjuvant and adjuvant modalities, particularly the timing of individual drugs, use of hyperthermia, and route of administration. The place of immunotherapy and gene therapy as adjunctive treatments also remains to be defined. For example, it may be possible to reduce tumor bulk and perhaps downstage the disease with immunotherapy before radical surgery, if treatment is started early enough. Gene therapy may have a role either preoperatively or in destroying the microscopic disease that remains after radical surgery. These and other combinations of treatment need to be tested in well-designed clinical trials, probably on a multicenter basis (to enroll a sufficient number of patients). Finding the means to improve treatment for sarcomatous and mixed histology mesothelioma remains a challenge. At present, radical surgery does not seem worthwhile for these patients when combined with currently employed chemotherapy and radiotherapy; however, chemotherapy combinations used for treating other sarcomas need to be evaluated as adjunctive therapy before radical surgery is abandoned altogether as a mode of treatment. A collaborative approach involving thoracic surgeons, basic scientists and oncologists, and physicians with experience in treating mesothelioma is essential. Despite its increasing frequency, mesothelioma is still a relatively rare tumor, so treatment should be concentrated in relatively few supraregional centers to maximize expertise and allow innovative treatment combinations to be implemented with the greatest chance of success. Evaluation of new therapeutic approaches will be achieved more rapidly if these supraregional centers collaborate in multicenter trials. The nihilistic approach of simply waiting until the mesothelioma epidemic eventually begins to decline spontaneously in 20 or 30 years is untenable in view of the hundreds of thousands of deaths that will result if no effective treatment is found.

High-dose hemithorax irradiation in a patient with recurrent thymoma: a study of pulmonary and cardiac radiation tolerance

Malignancy spread throughout a hemithorax without distant metastasis poses a difficult therapeutic challenge. Irradiation is often not considered because of the risk of pulmonary and cardiac toxicity. We report on a patient with thymoma recurrent throughout the left pleural cavity. Disease progressed despite chemotherapy, and subsequently a radical course of radiotherapy (6,600 cGy) was delivered to the entire hemithorax. Tumor regressed markedly by the completion of radiotherapy. Although tumor regrowth was noted 1 year after radiotherapy, the patient remained markedly improved symptomatically until shortly before her death 2 years after radiotherapy. Pulmonary function tests at 1 year (forced expiratory volume of the first second and forced vital capacity) were similar to pretreatment values, and cardiac function at 2 years remained essentially normal. High-dose hemithorax irradiation may be a consideration in select cases.

Advances in the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is a neoplasm that is commonly fatal and for which there are no widely accepted curative approaches. Mesothelioma is unresponsive to most chemotherapy and radiotherapy regimens, and it typically recurs even after the most aggressive attempts at surgical resection. Multimodality approaches have been of some benefit in prolonging survival of very highly selected subgroups of patients, but they have had a relatively small impact on the majority of the patients diagnosed with this disease. As the incidence of pleural mesothelioma peaks in the United States and Europe over the next 10 to 20 years, new therapeutic measures will be necessary. This review will discuss the roles of chemotherapy, radiotherapy, surgery, and combined modality approaches in the treatment of pleural mesothelioma, as well as scientific advances made in the past decade that have led to the development of experimental techniques, such as photodynamic therapy, immunotherapy, and gene therapy, that are currently undergoing human clinical trials. These promising new avenues may modify the therapeutic nihilism that is rampant among clinicians dealing with mesothelioma.

Factors influencing the outcome of radiotherapy in malignant mesothelioma of the pleura--a single-institution experience with 189 patients

PURPOSE

To determine the factors influencing the response to palliative radiotherapy (RT) in malignant mesothelioma of the pleura (MM).

METHODS AND MATERIALS

A retrospective review was conducted of the records of all patients with mesothelioma who were referred to our institution between 1979 and 1996. A total of 227 RT series were administered to 189 patients with MM. Of these, 21 patients with chest wall nodules also received concomitant local hyperthermia.

RESULTS

The median survival was 5 months from the start of RT and only 17% of patients were alive at 1 year after treatment. Chest pain and painful chest wall metastases were the main indications for RT. A higher local response rate was seen for patients treated with a 4-Gy per fraction scheme, vs. those receiving fractions of less than 4 Gy (50% vs. 39%). Pain recurrence occurred predominantly within the previous RT field, and pain recurred after a median of 69 days (range 32-363) in the group treated using 4-Gy fractions. When compared with a matched group, patients treated with combined RT and hyperthermia had higher response rates and fewer in-field recurrences.

CONCLUSIONS

RT provides local palliation in at least 50% of patients with MM who were treated using a 4-Gy/fraction scheme to a median dose of 36 Gy. The low response rates with RT alone suggest that combined RT and local hyperthermia should be further evaluated in MM.

[Problems in diagnosis and therapy of malignant pleural mesothelioma]

The incidence of malignant pleural mesothelioma increased continuously during recent years. This is related to widespread use and processing of asbestos in the last decades. Characteristical symptoms like dyspnea, cough and thoracic pain are common in almost all pulmonal diseases. Therefore the possible occurrence of a pleural tumor is often neglected. This leads to a delay between onset of symptoms and the establishment of diagnosis. With X-ray and computed tomography 80% of the pleural tumors can be proved. Only in few cases the histopathological analysis of the pleural fluid leads to diagnosis. However, thoracoscopy or thoracotomy remain the most reliable means of obtaining a definitive tissue diagnosis. At the time of operation advanced stages are found in many cases, therefore palliative surgery is indicated. Due to high morbidity and mortality pleuropneumonectomy should be done only in selected patients. Pleurectomy or pleurodesis is often sufficient to release patients' symptoms. Chemotherapy and radiation have not proven effective in controlling malignant mesothelioma. In conclusion pleural mesothelioma remains a tumor with a very poor prognosis. Long term survival is occasional even in case of multimodal treatment.

Altered fractionation of hemithorax irradiation for pleural mesothelioma and failure patterns after treatment

Malignant pleural mesothelioma is a rare malignancy with a bleak prognosis. The role of radiotherapy has not yet been clarified. Our aim was to study the effect of altered fractionation on mesothelioma. We have treated 57 patients, 41 males and 16 females, with hemithorax irradiation with six different fractionation schedules. All the patients have been included in a combined modality program consisting of surgery followed by chemotherapy and finally by hemithorax irradiation. The radiotherapy schedules used were: I. Conventional fractionation of 20 Gy in 10 fractions over 12 days. II. Split-course radiotherapy 55 Gy in 25 fractions of 2.2 Gy over 7 weeks (a two weeks rest halfways) followed by a boost dose of 15 Gy over 8 days to the major tumour area. III. Hyperfractionation of 70 Gy over 7 weeks, 1.25 Gy BID with a 6-h interval and a 10-day rest halfways. IV. Combined hyperfractionation and hypofractionation, 35 Gy hyperfractionation in 28 fractions (1.25 Gy BID with a 6-h interval) over three weeks followed by 36 Gy hypofractionation 9 fractions of 4 Gy given every other day over 3 weeks to the major tumour areas only. V. Hypofractionation of 38.5 Gy over 15 days (9 x 3.5 Gy). VI. Combined conventional radiotherapy and hypofractionation with 20 Gy given conventionally in 10 fractions followed by 10 fractions of 3 Gy over two weeks, overall time 4 weeks. The 2-year survival rate of all patients was 21% and the 5-year survival rate 9%. Two patients are still alive more than 6 and 9 years after radiotherapy. Progression occurred after surgery in four patients, during and after chemotherapy in 22 patients and after completed radiotherapy in 29 patients. The pattern of progression was similar in each treatment group.

Aspects of histopathologic subtype as a prognostic factor in 85 pleural mesotheliomas

BACKGROUND

The prognosis of patients with pleural mesothelioma is more dependent on "pretreatment factors" than on the effect of therapeutic interventions. Histopathologic subtype is one of several important prognostic factors in pleural mesothelioma, and several studies indicate that the epithelial subtype of pleural mesotheliomas has a more favorable prognosis than the sarcomatoid. In this study, we retrospectively evaluated qualitative and quantitative aspects of the tissue specimens used for histopathologic diagnosis in 85 patients with pleural mesothelioma.

MATERIALS AND METHODS

The prognostic roles of two different histopathologic classification systems were evaluated in 85 consecutive cases of pleural mesotheliomas. Efficiency of different diagnostic procedures, influence of the size of the biopsy specimens on the histopathologic diagnosis, and immunohistochemical profiles for histopathologic subtypes of mesotheliomas were also evaluated.

RESULTS

Patients with pure epithelial mesotheliomas (n = 35), and especially those with the tubulopapillary subtype (n = 18) of epithelial mesotheliomas, survived significantly longer than those with a sarcomatoid component (n = 50). With larger biopsy specimens (surgical biopsy, autopsy), more tumors were classified as biphasic (36/78 vs 9/44, p < 0.005). The sarcomatoid mesotheliomas comprised about 20% of the tumors regardless of type of biopsy. Staining intensity for cytokeratin CAM 5.2 was equal in all types of mesotheliomas, while intensity with cytokeratin AE1/AE3 decreased from the epithelial to the sarcomatoid mesotheliomas. Staining with vimentin was most intense among the sarcomatoid mesotheliomas, while with epithelial membrane antigen it was most intense among the epithelial mesotheliomas.

CONCLUSIONS

The quality of the biopsy specimens has considerable impact on the possibility to arrive at a correct histopathologic diagnosis. Based on our results, we suggest tubulopapillary mesotheliomas be regarded as "low-grade mesotheliomas" and other types, including the epithelioid type of epithelial mesotheliomas, as "high-grade mesotheliomas." This should be taken into account when designing clinical trials.

Prevention of malignant seeding after invasive diagnostic procedures in patients with pleural mesothelioma. A randomized trial of local radiotherapy

The purpose of this randomized prospective study was to assess the efficacy of local radiotherapy in preventing malignant seeding along invasive diagnostic procedures (cytology, needle biopsy, thoracoscopy, or chest tube placement) in patients with malignant pleural mesothelioma. Forty consecutive patients with histologically proven malignant mesothelioma were enrolled. Twenty patients received three daily sessions of radiotherapy at a dosage of 7 Gy 10 to 15 days after thoracoscopy. The other 20 patients did not receive radiotherapy. None of the 20 patients treated developed entry tract metastasis. In contrast, 8 of the 20 (40%) patients who were not treated developed metastases. These findings confirm the efficacy and safety of early local radiotherapy in preventing malignant seeding after invasive diagnostic procedures in patients with malignant pleural mesothelioma.

Evaluation of the clinical TNM staging system for malignant pleural mesothelioma: an assessment in 88 patients

There is no universally-recognised method for staging malignant mesothelioma, although the use of computed tomograph (CT) scanning has improved the staging of non-invasive disease. The International Union against Cancer has recently proposed using the Tumour Node Metastases (TNM) staging system for mesothelioma, but in clinical practice it is difficult to assess tumour and nodal involvement due to the unique plate-like growth pattern of this tumour. In order to evaluate TNM staging we analysed pre-operative CT scans from 88 patients with histologically-confirmed malignant pleural mesothelioma, all from the same institution. The median age of the patients was 56 years (range 38-79). There were 70 men and 18 women, and 33 had tumours with epithelial histology. The median survival time was 10 months (range 0.2-110), from the date of histological confirmation of mesothelioma. The same radiologist analysed all the CT scans according to the TNM staging system. Actuarial survival curves were constructed by the Kaplan-Meier method. Survival curves for the different TNM categories were compared using the log-rank test. Node evaluation could not be completed in eight cases because the tumour had encompassed the hilum and mediastinum. In multivariate analysis, significant differences in prognosis correlated with the different T categories (P < 0.01), and the different TNM stages (P < 0.05), but not the N categories or the M categories. Larger studies are needed to assess the importance of TNM staging in the selection of treatment and as a prognostic factor for malignant mesothelioma.