Phase III randomized trial of surgery with or without intraoperative photodynamic therapy and postoperative immunochemotherapy for malignant pleural mesothelioma

Photodynamic therapy in the management of malignant pleural mesothelioma: A review

BACKGROUND

In the past decade there have been sporadic publications on malignant pleural mesothelioma (MPM). In the present trend of multi-modal treatment for MPM we aim to evaluate the current status of photodynamic therapy (PDT) in the management of MPM through a review study.

METHODS

Original publications in English were the main source of the review and their material analysed in respect of patient and disease characteristics, PDT methods, mortality and morbidity and survival. Ten articles concerned with 230 patients were analysed and 35 other publications relevant to the study were used for reference. In every case PDT was used as an adjuvant to surgery whose role appeared to be a cyto-reductive procedure of debulking, pleurectomy and decortication (DPD) with/without pulmonary resection. PDT methods used two photosensitisers; Photofrin™ [630nm laser light] (6 series=170 patients) or Foscan™ [652nm laser light] (4 series=60 patients).

RESULTS

Overall mortality and morbidity was 7.1% (4.9% for Photofrin™ and 13.3% for Foscan™ PDT) and 48% (38% for Photofrin™ and 70% for Foscan™ PDT) respectively. Better survival was achieved for DPD and early stage disease.

CONCLUSIONS

Intra-operative (IOP) PDT in MPM is a safe procedure that requires more development and work regarding photosensitisers and light distribution systems for use in intra-pleural situations. The role of surgery in IOP-PDT appears to be cyto-reduction to ≤5mm residual tumour thickness in order for PDT to be used effectively. Curative intent may depend on the stage of MPM and completeness of cyto-reduction with/without pulmonary resection.

Induction chemotherapy, extrapleural pneumonectomy, and radiotherapy in the treatment of malignant pleural mesothelioma: The Memorial Sloan-Kettering experience

Approximately 25% of patients with malignant pleural mesothelioma (MPM) prove unresectable at surgery and the median survival of stage III MPM is <12 months even after complete resection by extrapleural pneumonectomy. From 1939-2004, a series of sequential clinical trials has been performed at our institution. The surgical procedure has been modified and improved upon, and adjuvant hemithoracic radiation (RT) standardized. The evolution of our current standard of care for MPM is discussed. Improving chemotherapy for MPM led us to test induction chemotherapy followed by EPP and adjuvant RT for locally advanced MPM to assess feasibility. Patients with T3-4 or N2 MPM by CT and PET scans were enrolled on a phase II study. Induction therapy was: gemcitabine (1250 mg/m2 days 1, 8) and cisplatin (75 mg/m2 day 8)x2-4 cycles. Patients underwent EPP 3-5 weeks after induction therapy, then 54 Gy RT 4-6 weeks postop. At surgery, 8/9 had complete resection by EPP with no postoperative deaths. All received planned adjuvant RT. This combined modality approach is feasible for locally advanced MPM, and initial analysis suggests improved resectability. This experience supports additional studies of induction and multimodality therapy, especially with regimens such as cisplatin and pemetrexed which may be better tolerated and more effective.

Photodynamic therapy as an adjunct to surgery for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is increasingly observed in industrial countries. Despite concerted efforts and combined treatments including surgery, chemotherapy and irradiation patients eventually succumb from relentless local progression of the disease. Recent publications have demonstrated an improved response rate with the cytostatic agent pemetrexed which will be tested in a neoadjuvant setting followed by surgery. However, effective tumor control requires new loco-regional treatment modalities, eventually in combination with neoadjuvant chemotherapy. Intraoperative photodynamic therapy (PDT) of the chest cavity has been proposed as an attractive treatment concept for MPM since a selective treatment of the tumor bed following resection has the potential to improve local tumor control. It has been shown to afford tumor destruction in patients with mesothelioma but efficiency and selectivity is not yet sufficient for routine clinical application. Experimental work on MPM has shown that tumor selectivity of PDT depend on treatment conditions and can be improved by structural modification and improved targeting of the sensitizers. Refinements of PDT for mesothelioma will depend on a more detailed understanding of the pathways for preferential sensitizer accumulation within the tumor as well as on synergistic effects between PDT and chemotherapeutic agents.

A review of progress in clinical photodynamic therapy

Photodynamic therapy (PDT) has received increased attention since the regulatory approvals have been granted to several photosensitizing drugs and light applicators worldwide. Much progress has been seen in basic sciences and clinical photodynamics in recent years. This review will focus on new developments of clinical investigation and discuss the usefulness of various forms of PDT techniques for curative or palliative treatment of malignant and non-malignant diseases.

Malignant pleural mesothelioma

Malignant pleural mesothelioma is an uncommon tumor; only about 3000 cases are diagnosed annually in the United States. Cases were described early in the 20th century, but their relationship to asbestos exposure was not documented until 1960. Since then, the incidence has appeared to increase, and numerous epidemiologic studies have confirmed that exposure to asbestos in a variety of settings and occupations is the most significant risk factor for the development of malignant pleural mesothelioma. More recently, the oncogenic virus SV40 has also been implicated as a potential etiologic agent. Surgery, radiotherapy, and chemotherapy have each been used in the treatment of mesothelioma, but generally with little impact on survival. New directions in therapy include aggressive multimodality programs for potentially resectable patients and targeted therapies, including antifolates, antiangiogenesis agents, and drugs directed at epidermal growth factor receptor for the majority of patients presenting with unresectable disease.

Surgical management of malignant pleural mesothelioma: a systematic review and evidence summary

An evidence summary was developed for the surgical management of adult patients with diffuse or localized malignant pleural mesothelioma. This evidence summary is based on a systematic search and review of the literature published between 1985 and February 2004. Relevant studies were identified, according to pre-determined criteria by the authors and methodologists. No randomized controlled trials comparing pleurectomy (PL) with extrapleural pneumonectomy (EPP) or comparing surgery with an alternative treatment were identified. Four comparative studies, seven non-comparative prospective studies, and 16 retrospective case series were identified that looked at PL, or EPP, or PL and EPP. Trial results were not pooled due to the heterogeneity of the treatments in the trials and the fact that no trials were randomized and none were designed to directly compare different treatments. External feedback was obtained from Ontario clinicians, and the provincial Lung Cancer Disease Site Group approved the review.

CONCLUSIONS

The role of surgery in the management of malignant pleural mesothelioma cannot be precisely defined as the lack of randomized controlled clinical trials makes it impossible to determine whether the use of EPP or PL improves survival or effectively palliates the symptoms of the disease. Future studies of the role of surgery in the treatment of mesothelioma should include evaluations of quality of life.

Intraoperative photodynamic therapy of the chest cavity in malignant pleural mesothelioma bearing rats

BACKGROUND AND OBJECTIVE

Experimental assessment of anticancer effect, normal tissue damage, and toxicity of intrathoracic mTHPC-mediated photodynamic therapy (PDT) combined to surgery in malignant pleural mesothelioma (MPM) bearing rats.

STUDY DESIGN/MATERIALS AND METHODS

Six days after implantation of syngenic malignant mesothelioma cells in the left chest cavity of Fischer rats (n = 21) and 4 days after sensitization (0.1 mg/kg mTHPC), a left-sided pneumonectomy was performed, followed by intraoperative light delivery (652 nm, fluence 20 J/cm(2)), either by spherical illumination of the chest cavity (fluence rate 15 mW/cm(2)) or by focal illumination of a tumor area (fluence rate 150 mW/cm(2)). Controls comprised tumor-bearing untreated animals, tumor-bearing animals undergoing pneumonectomy, and tumor-bearing animals undergoing pneumonectomy and light delivery without sensitization or sensitization without light delivery. No thoracocentesis was performed during follow-up.

RESULTS

An invasively growing sarcomatous type of mesothelioma was found in all animals at day 10, without tumor necrosis in control animals. PDT resulted in 0.5-1 mm deep inhomogeneous tumor necrosis after spherical, and in a 1-2 mm deep tumor necrosis after focal illumination. No injury to mediastinal organs was observed, neither after PDT with spherical nor with focal light delivery except focal interstitial lung fibrosis at the mediastinal area of the opposite lung. All animals with pneumonectomy followed by spherical PDT of the entire tumor-bearing chest cavity died within 72 hours whereas all other animals survived. All animals that died presented massive pleural effusion.

CONCLUSIONS

PDT following pneumonectomy in mesothelioma bearing rats was technically feasible and allowed to study its effect on tumor and normal tissues. PDT-related tumor necrosis was observed after spherical and focal light delivery, however, pneumonectomy followed by PDT with spherical light delivery to the tumor-bearing chest cavity resulted in fatal complications.

Innovative therapies: photodynamic therapy

Photodynamic diagnosis could be a useful tool for improving the diagnostic yield of tumor biopsy, especially for mesothelioma tumors that are sclerotic and particularly hypocellular. For PDD, the use of low doses of a sensitizing drug, such as 5-ALA, must be investigated further. The initial results of 5-ALA-mediated PDD are promising. The role, if any, for PDT in the treatment of mesothelioma has yet to be established. The number of centers exploring this technology is limited because the procedure is labor intensive and requires not only specialized equipment but also physician support. The number of patients treated in the different trials is small, and no definitive conclusions can be drawn. Further complicating the interpretation of published results is the number of variables (i.e., type of sensitizer, light dose, drug dose, drug light interval, methods of light measurement, technique of light delivery, surgical debulking techniques), which differ between studies. Most reports are phase I and II studies. The final outcome of these studies with respect to survival is of limited value. The only phase III study, which was performed with an earlier generation photosensitizer, reported no advantage to the use of PDT in combination with surgery and immunochemotherapy. To date, the most that can be said is that intraoperative PDT can be performed safely in experienced centers and that there are some encouraging results, especially in patients with stages I and II MPM, particularly with the newer generation photosensitizers. One attractive aspect of this adjuvant treatment is that PDT, as opposed to some of the other adjuvant treatments combined with surgery, may offer the option of effecting adequate tumor debulking with a pulmonary-sparing procedure.

Innovative therapies: intraoperative intracavitary chemotherapy

Both phase I studies demonstrated that high-dose cisplatin can be delivered safely with acceptable complication rates. The maximum tolerated doses of 225 mg/m2 and 250 mg/m2 cisplatin, respectively, are higher than any other published report of intrapleural cisplatin. The intrapleural cisplatin doses reported in other trials have been 80 mg/m2, 100 mg/m2, and 200 mg/m2. Despite the use of high-dose intraoperative chemotherapy, the group of 50 patients who underwent EPP experienced mortality and morbidity comparable to the contemporaneous group of 41 patients who did not participate in the protocol, except for increased rates of deep venous thrombosis and diaphragmatic patch failure. The 44 patients who underwent P/D experienced a slightly higher mortality rate and creatinine toxicity rate than the first phase I trial. Given the demographics of this patient cohort (higher age, lower FEV1, and inability to withstand pneumonectomy because of limited cardiopulmonary reserve), however, the mortality and morbidity rates seem acceptable. The pharmacologic data from both studies support our hypothesis that high regional doses of cisplatin can be delivered with less systemic absorption than can be achieved with intravenous administration (data not shown). With the maximum tolerated dose of intracavitary cisplatin and safety of intraoperative administration after surgical resection firmly established by these phase I trials, we are prepared to implement phase II and III studies of EPP and P/D with intraoperative cisplatin lavage. We aim to monitor tumor recurrence and patient survival prospectively and compare these results with historic controls. We also intend to document prospectively the morbidity and mortality of the treatment protocols. Finally, we plan to evaluate the pharmacokinetics of cisplatin by measuring tissue and perfusate levels of active and inactive cisplatin. By approaching the problem of local recurrence after resection of MPM in a careful and methodical manner, we hope to decrease or delay the rate of recurrence and potentially improve longterm survival in patients with this lethal disease.

Extrapleural pneumonectomy for diffuse malignant pleural mesothelioma: techniques and complications

Innovative therapeutic agents and strategies are being investigated to improve survival with this lethal disease. New chemotherapy agents, including gemcitabine (Eli Lilly and Company; Indianapolis, Indiana) and pemtrexed (Eli Lilly and Company) show promise against mesothelioma. Kaiser has reported using novel therapies, such as cytokines and suicide gene therapy, to target mesothelioma. Pass et al , Moskal et al , Schouwink et al , and Friedberg et al have applied photodynamic therapy to the hemithorax after surgical resection. Because recurrence of mesothelioma after surgical resections tends be locoregional rather than distant , strategies to improve local control may be beneficial. Several groups, including our Brigham and Women's Hospital Thoracic Surgery Division and Dana Farber Thoracic Oncology Program, are investigating intraoperative intracavitary lavage of hyperthermic chemotherapy immediately after EP (discussed elsewhere in this issue). Although mesothelioma remains a difficult disease to treat, the techniques of surgical resection for mesothelioma have improved dramatically. Currently, EPP can be performed with acceptable morbidity and mortality at experienced centers.

Pleurectomy and decortication for malignant mesothelioma

P/D in combination with other therapies remains an effective weapon in the thoracic surgeon's armamentarium for treating patients with MPM, particularly patients with limited lung function. A clear benefit has been demonstrated in terms of symptom relief. Further strategies aimed at eliminating residual disease in an effort to prevent locoregional recurrence and as potential curative therapies currently are being investigated.

Patterns of failure following surgical resection for malignant pleural mesothelioma

The optimum therapeutic strategy for patients with localized malignant mesothelioma continues to evolve. For patients who are eligible candidates, surgical resection plays an important role. An encouraging 45% 5-year survival rate has been reported for patients with early-stage disease who undergo EPP and have the favorable features of epithelial histology and the absence of mediastinal lymph node involvement. Most patients present with more advanced disease, however, and the optimum local and systemic treatment for these patients has not been defined. No randomized trials evaluating the various surgical or adjuvant therapeutic approaches have been performed. Evaluation of treatment efficacy based on observed patterns of failure may suffer from treatment selection biases. Most studies also do not separate out the failure patterns based on the initial stage (clinical or pathologic) of the disease. Consequently, it is difficult to discern the potential impact of a given adjuvant therapy. Given these limitations, however, some consistent observations from the available data can be made. For patients who undergo P/D, local recurrence (within the surgically operated hemithorax) is the most common form of recurrence. Efforts to decrease the chance of local recurrence after P/D have included the use of intrapleural and intravenous chemotherapy, brachytherapy, and external beam radiation therapy. None of these adjuvant treatment trials was randomized, and when compared with historical controls, none of the treatments used suggested a consistent outcome benefit. After P/D, the use of radiation is limited by the potential toxicity of the underlying organs, most importantly, the intact lung. Doses required to treat mesothelioma effectively are above the doses that would lead to damage to the lung parenchyma. Cisplatin and mitomycin have been used as agents have modest activity against mesothelioma. The doses of cisplatin used may not have been optimal, although they were based on prior pharmacokinetic studies. Alternative approaches for patients who undergo P/D, such as the use of escalating doses of heated intrapleural cisplatin (given with a renal protecting agent, sodium thiosulfate, which provides the opportunity to deliver higher doses of chemotherapy), are being pursued by Sugarbaker et al. The availability of more active systemic chemotherapy agents or other intrapleural agents also may offer better therapeutic options for patients who undergo P/D. Recently, Vogelzang et al presented the findings of a large randomized study that compared cisplatin/premetrexed to cisplatin and demonstrated an improvement in response rate (41% for cisplatin/pemetrexed versus 19% for cisplatin) and median survival (12.1 versus 9.3 months, respectively; P = 0.020). Other chemotherapy regimens with encouraging activity in mesothelioma include the combination of cisplatin and gemcitabine, with response rates ranging from 16% to 48%. From a review of available data, patients with mesothelioma who have undergone P/D (with or without intrapleural chemotherapy) who are evaluated at the Dana Farber Cancer Institute and Brigham and Women's Hospital are offered therapy with systemic chemotherapy alone. After P/D, radiation is used only for palliative treatment. Patients who have undergone P/D are also appropriate candidates to receive chemotherapy or other novel therapeutic strategies being evaluated in clinical trials. For patients who have undergone EPP, the pattern of recurrence is predominantly a combination of local and distant failure (Table 1). The local recurrence rates, however, seem to be lower than rates seen after P/D. This observation may represent a shift of the natural history of the disease. Metastatic mesothelioma is often seen late in the course of the disease, but it may become the dominant source of disease after aggressive local surgical management. Many studies define abdominal recurrence as a site of distant recurrence, although this may represent transdiaphragmatic extension of the pleural mesothelioma. Advances in local therapy also may decrease the rate of abdominal recurrences. True distant recurrences (bone, central nervous system, contralateral hemithorax) remain less common. The lowest rate of local recurrence (13%), with a 4% local-only recurrence rate, was seen in the study by Rusch et al, who used 54 Gy hemithorax radiation as adjuvant therapy. This is the lowest rate of local recurrence after an EPP that has been reported. Baldini et al reported a 50% local recurrence rate, with a 13% local-only rate, after trimodality therapy. One possibility for the differences between these two reports is the lower dose of radiation (30.6 Gy) used in the latter study. In the study by Rusch et al, distant failures predominate, and the patients are appropriate candidates for systemic chemotherapy, which could be administered either as neoadjuvant or adjuvant therapy. Kestenholz et al currently are performing a phase II clinical trial of neoadjuvant cisplatin and gemcitabine administered for three cycles followed by EPP and adjuvant radiation therapy. A similar approach also is being pursued in an ongoing clinical trial using neoadjuvant cisplatin/pemetrexed for four cycles before EPP followed by 54 Gy of adjuvant hemithorax radiation. Alternatively, patients who have undergone EPP could be treated with adjuvant chemotherapy in addition to adjuvant radiation therapy. Currently, patients evaluated at the Dana Farber Cancer Institute and Brigham and Women's Hospital who have undergone EPP are offered adjuvant chemotherapy followed by hemithorax radiation to 54 Gy in an effort to maximize local and distant control rates. Further clinical studies are needed for all patients with mesothelioma to define the optimum surgery and duration and types of adjuvant therapy. The appropriate multimodality approaches most likely will differ based on disease stage, histology, and patient performance status. intrapleural chemotheraphy treatments. These two For Patients who have undergone EPP, the pattern

Malignant Pleural Mesothelioma

The diagnosis and management of malignant pleural mesothelioma are major challenges that often frustrate both patient and clinician alike. Occupational asbestos exposure to crocidolite or amosite forms of the fiber is the most important known risk factor in North America and Western Europe. Other mineral fibers such as erionite, a naturally occurring fibrous zeolite crystal, are associated with mesothelioma in volcanic tuffs of the Cappadocia region of central Anatolia in Turkey. In addition, other possible factors such as the presence of simian virus 40 and genetic susceptibility have been associated recently with the development of mesothelioma in animal models. These latter findings are increasing our understanding of this disease. In addition, the discovery of elevated levels of various markers such as folic acid receptor alpha, cyclooxygenase 2, and multidrug resistance proteins 1 and 2 in mesothelioma tissue have opened up new areas of potential diagnostic and therapeutic importance. However, traditional treatment modalities--surgery, radiotherapy, and chemotherapy--have evolved slowly, and few gains in therapeutic efficacy have occurred. Recently, however, continuing research efforts have led to novel treatment strategies that are changing the way clinicians view a disease that has traditionally been managed with almost universal therapeutic nihilism. This review explores our current knowledge of this disease and presents current and novel therapeutic strategies.

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.

Malignant pleural mesothelioma--an update

Exposure to asbestos is the most frequent, but not exclusive, cause of malignant mesothelioma. Clinical features include dyspnea, cough, nonspecific chest pain, weight loss and night sweats. Diagnosis may be complicated by histologic difficulties. Thoracoscopic techniques are proving beneficial, but no one method of imaging has proven superior, and disease staging is inconsistent. Conventional treatments such as chemotherapy, surgery, and radiotherapy have had variable impacts, although chemotherapy is useful in palliation and can improve both survival and quality of life. There is hope for new antimetabolite agents. The role of radical surgery is yet to be evaluated in a large trial. New radiotherapeutic techniques to improve local control are promising. Multimodality treatments appear to be the most successful for management of potentially resectable disease. It is likely that biological markers will improve accuracy in staging and prognosis. With new treatments based on better understanding of the biology of the disease, there is cautious optimism for the future for patients with malignant pleural mesothelioma.

Intraoperative radiation therapy in the multimodality approach to upper aerodigestive tract cancer

The cure rate of operable lung cancer and locally advanced head and neck cancer remains suboptimal, with a limited rate of local control despite improvements in the surgical removal of primary tumors and in methods for mediastinal lymph node dissection, in particular. The efficacy of adjuvant therapy, such as EBRT, has improved, and the immediate efficacy of new chemotherapeutic drugs is increasingly significant, although local recurrences remain frequent. Locoregional failure is not uncommon in upper aerodigestive tract cancers. Factors limiting radiocurability for locally advanced (stage III) lung cancer include mediastinal intolerance of irradiation (high risk of mediastinal fibrosis, which increases exponentially when levels of much more than 50 Gy are administered to the whole mediastinum) and the very high radiosensitivity of the healthy lung, which can develop fibrosis with relatively small or moderate doses starting at 18 to 20 Gy, and even more frequently when larger volumes are irradiated. Head and neck neoplasms are less difficult sites in which to administer doses of up to 70 Gy of external beam radiotherapy initially, but, like locoregionally recurrent lung cancers, they are not easily reirradiated with tumoricidal doses of EBRT. For these reasons, IORT seems to be a good option for increasing local control, because areas of [figure: see text] residual microscopic disease may be irradiated using IOERT approaches without affecting critical organs to the same extent. In addition, careful patient selection is paramount. Combined modality treatment regimens incorporating IORT may benefit patients with locally advanced disease. The ability of IORT to sterilize microscopic residual disease can enhance the "completeness" of resection and thus, theoretically, improve local control. Although distant disease dissemination remains by far the overriding issue, as newer effective agents emerge, local failure will continue to be a problem. Preliminary studies have demonstrated that IORT can be administered to patients who have locally advanced NSCLC and head and neck cancer, in the context of aggressive combined modality therapy, and is generally well tolerated. Long-term efficacy and benefit can only be determined in the setting of carefully designed clinical trials. (See the article by Thomas and Merrick elsewhere in this issue for further discussion of this topic.) Several relatively small, single-institution pilot studies exploring the utility and benefit of IORT for locally advanced upper aerodigestive tract cancers have been conducted. Clear conclusions have been difficult to determine because of the mixing of disease stages, varying degrees and completeness of surgical resection, varying radiation doses, different schemas, and other factors. Yet, given the major morbidity and mortality associated with locally recurrent lung cancer, methods of improving local control need to be pursued and refined. Encouraging preliminary data suggest that IOERT can be safely administered and may benefit local control. Based on several centers' expertise in the combined modality treatment of locally advanced lung cancer and familiarity with IORT, the UCSF Thoracic Oncology Program has proposed a multicenter phase 2 study incorporating IORT in a combined multimodality treatment schema for patients who have completely resected locally advanced stage IIIA and IIIB NSCLC (nonpleural effusion, non-N3) (Fig. 1). It is hoped that this study will commence in the upcoming year.

Integration of Multimodality Approaches in the Management of Malignant Pleural Mesothelioma

More than half a century after the first descriptions of mesothelioma as a pathologic entity, satisfactory treatment is still elusive. Although relatively uncommon, the incidence of mesothelioma will most likely increase over the next 10-20 years. Advances have been made in understanding the pathogenesis, diagnosis, and staging, but they have not translated into markedly improved survival. Some use palliative treatment as the primary means of therapy even now. On the other hand, a cadre of individuals have studied how surgery, chemotherapy, and radiation therapy affect the disease. Although each individual modality has had limited success by itself, a multimodality approach has been documented to improve survival and quality of life. In addition, intriguing discoveries in immunology and gene profiling and therapy promise hope for further improvement. In this article, we will illustrate the current views on integrating these different approaches and delineate areas of active research.

Malignant pleural mesothelioma: surgical roles and novel therapies

Malignant pleural mesothelioma (MPM) is a uniformly fatal disease that has been recalcitrant to curative therapies. Median survivals of 8-18 months have, for the most part, led to a sense of frustration and nihilism in the medical and surgical community with regard to management of the disease, and the relatively small numbers of patients with mesothelioma have made it an orphan among other cancers with regard to research efforts and funding. This review will comment on the clinical presentation of the disease and therapeutic options that are available at this time. The role, timing, degree, and availability of cytoreductive surgery in the context of a multimodality approach for MPM will be highlighted, and various strategies that incorporate adjunctive therapies before, during, or after the operation will be discussed. Newer cytotoxic chemotherapies, either alone or in combination, are reviewed, with an emphasis on the increasing number of options with increased response rates that are becoming available for MPM patients. The results of protocols at selected centers that offer gene therapy, photodynamic therapy, hyperthermic chemotherapeutic perfusion, and intrapleural chemokines will be discussed, as well as newer preclinical approaches that base targeted therapies on novel molecular findings. In considering the newest approaches to the disease, one is encouraged to seek specialty consultation at centers that concentrate programmatic efforts on mesothelioma in order to design translational-based approaches on preclinical findings. By using such an approach, the patient and physician will find that there are considerably more options in the new century for mesothelioma.

Elevated serum cytokine levels in mesothelioma patients who have undergone pleurectomy or extrapleural pneumonectomy and adjuvant intraoperative photodynamic therapy

Patients treated on a Phase-I clinical trial of photodynamic therapy (PDT) developed a systemic capillary leak syndrome that constituted the dose-limiting toxicity. We examined serum samples from patients treated at the maximally tolerated dose level for evidence of a systemic, cytokine-mediated inflammatory response. Patients underwent pleurectomy or extrapleural pneumonectomy (EPP) followed by intraoperative PDT of the thorax using Foscan at a dose of 0.1 mg/kg 6 days before surgery and 652 nm red light at a dose of 10 J/cm2. Levels of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, IL-8, IL-10 and IL-12 were assayed before Foscan administration; after anesthetic induction, surgical resection and light delivery; in postoperative recovery and the day after the surgery. Of the analyzed patients, eight underwent a pleurectomy and one an EPP followed by PDT. IFN-gamma, TNF-alpha and IL-12 showed no elevation, but IL-1beta, IL-6, IL-8 and IL-10 levels were elevated after surgery and PDT. IL-1beta showed a statistically significant variation from baseline after surgery and IL-6, after PDT. The results suggest a systemically mediated inflammatory response resulting from thoracic surgery followed by PDT. Further investigation of specific mechanisms is warranted.

The value of chest computer tomography and cervical mediastinoscopy in the preoperative assessment of patients with malignant pleural mesothelioma

BACKGROUND

Patients with localized malignant pleural mesothelioma (MPM) can be considered for surgical resection with or without additional treatment. For this approach it is imperative to select patients without mediastinal lymph node involvement. In this study cervical mediastinoscopy (CM) is compared with computer tomography (CT) scanning for its diagnostic accuracy in assessing mediastinal lymph nodes during preoperative workup.

METHODS

Computer tomography scans of the chest and CM were performed in 43 patients with proven unilateral MPM. The CT scans were reviewed by one radiologist and two chest physicians. At CM the lymph node samples were taken from stations Naruke 2, 3, 4, and 7. Computer tomography and CM results were compared with final histopathologic findings obtained at thoracotomy or, if this was not performed, at CM.

RESULTS

Computer tomography scanning revealed pathologic enlarged lymph nodes with a shortest diameter of at least 10 mm in 17 of 43 patients (39%). There was histopathologic evidence of lymph node metastases at CM in 11 of these patients (26%). This resulted in a sensitivity of 60% and 80%, a specificity of 71% and 100%, and a diagnostic accuracy of 67% and 93% for CT and CM, respectively.

CONCLUSIONS

Cervical mediastinoscopy is a valuable diagnostic procedure for patients with MPM who are considered candidates for surgical-based therapy. Results of CM are more reliable than those obtained by CT scanning. Our data confirm results of previous studies reporting that mediastinal lymph node involvement is a frequent event in MPM.

Experimental photodynamic therapy for malignant pleural mesothelioma with pegylated mTHPC

BACKGROUND AND OBJECTIVES

Experimental assessment of photodynamic therapy (PDT) for malignant pleural mesothelioma using a polyethylene glycol conjugate of meta-tetrahydroxyphenylchlorin (PEG-mTHPC).

STUDY DESIGN/MATERIALS AND METHODS

(a) PDT was tested on H-meso-1 xenografts (652 nm laser light; fluence 10 J/cm(2); 0.93, 9.3, or 27.8 mg/kg of PEG-mTHPC; drug-light intervals 3-8 days). (b) Intraoperative PDT with similar treatment conditions was performed in the chest cavity of minipigs (n = 18) following extrapleural pneumonectomy (EPP) using an optical integrating balloon device combined with in situ light dosimetry.

RESULTS

(a) PDT using PEG-mTHPC resulted in larger extent of tumor necrosis than in untreated tumors (P < or = 0.01) without causing damage to normal tissue. (b) Intraoperative PDT following EPP was well tolerated in 17 of 18 animals. Mean fluence and fluence rates measured at four sites of the chest cavity ranged from 10.2 +/- 0.2 to 13.2 +/- 2.3 J/cm(2) and 5.5 +/- 1.2 to 7.9 +/- 1.7 mW/cm(2) (mean +/- SD). Histology 3 months after light delivery revealed no PDT related tissue injury in all but one animal.

CONCLUSIONS

PEG-mTHPC mediated PDT showed selective destruction of mesothelioma xenografts without causing damage to intrathoracic organs in pigs at similar treatment conditions. The light delivery system afforded regular light distribution to different parts of the chest cavity.

A phase I study of Foscan-mediated photodynamic therapy and surgery in patients with mesothelioma

BACKGROUND

Photodynamic therapy (PDT) is a light-based cancer treatment that, in the correct setting, can be delivered intraoperatively as an adjuvant therapy. A phase I clinical trial combining surgical debulking with Foscan-mediated PDT was performed in patients with malignant pleural mesothelioma. The purpose of the study was to define the toxicities and to determine the maximally tolerated dose (MTD) of Foscan-mediated PDT.

METHODS

A total of 26 patients completed treatment. Tumor debulking was accomplished with either an extrapleural pneumonectomy (7 patients) or a lung-sparing pleurectomy-decortication (19 patients). Patients were injected with Foscan before surgery, and 652 nm light was delivered intraoperatively after completion of surgical debulking. Four light sensors were placed in the chest, allowing delivery of light to a uniform measured dose throughout the hemithorax.

RESULTS

Four dose levels were explored. The MTD was 0.1 mg/kg of Foscan injected 6 days before surgery in combination with 10 J x cm(-2) 652 nm light. Dose limiting toxicity at the next higher dose was a systemic capillary leak syndrome leading to death in 2 of 3 patients treated at that dose. Other PDT-related toxicities included wound burns and skin photosensitivity. In all, 14 patients were treated at the MTD without significant complications.

CONCLUSIONS

Foscan-mediated PDT can be safely combined with surgery at the established MTD. Unlike most other surgery-based multimodal treatments for mesothelioma, Foscan-mediated PDT affords the option, in selected patients, of accomplishing tumor debulking with a lung-sparing procedure rather than an extrapleural pneumonectomy. A phase II study is warranted.

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.

Radical pleurectomy/decortication and intraoperative radiotherapy followed by conformal radiation with or without chemotherapy for malignant pleural mesothelioma

OBJECTIVES

We performed a retrospective review of the efficacy and morbidity of radical pleurectomy/decortication and intraoperative radiotherapy followed by external beam radiation therapy with or without chemotherapy for diffuse malignant pleural mesothelioma.

METHODS

A total of 32 patients with diffuse malignant pleural mesothelioma were initially evaluated between January 1995 and September 2000. Three patients were excluded from analysis because of unresectable disease. Two patients died postoperatively, and one patient had recurrent disease previously treated at an outside institution. Of the remaining 26 patients included in the analysis, 24 received intraoperative radiotherapy. External beam radiation therapy was generally started 1 to 2 months after resection and delivered by means of 3-dimensional conformal radiation therapy or with inverse treatment planning intensity-modulated radiation therapy. When given, chemotherapy consisted of 2 to 3 cycles of cyclophosphamide, doxorubicin (Adriamycin), and cisplatin initiated 1 to 2 months after completion of radiation.

RESULTS

At the time of data analysis, 5 of 26 patients were alive. The median follow-up was 9.7 months (range, 2-67.6 months). The median overall survival and progression-free interval from the time of the operation were 18.1 and 12.2 months, respectively. The Kaplan-Meier estimates of overall survival and freedom from progression at 1 year were 64% and 50%, respectively. The site of failure was mostly locoregional. However, there were 4 abdominal failures and 1 contralateral lung failure.

CONCLUSIONS

Radical pleurectomy/decortication with aggressive radiotherapy with or without chemotherapy might offer an alternative treatment option to those who cannot tolerate extrapleural pneumonectomy.

Current therapy for malignant mesothelioma

This review briefly summarizes the results of previous systemic (chemotherapy) and local (surgery and radiotherapy) treatment attempted to date for malignant mesothelioma. The prospects for newer modalities, ie molecular and biologic therapies, are also highlighted, including results of both preclinical and early clinical research.

Current surgical management of malignant pleural mesothelioma

Malignant pleural mesothelioma is a rare and very aggressive malignancy with an increasing incidence. Single-modality therapy has failed to improve median survival. Current surgical therapies include palliative and cytoreductive procedures. The rarity of the disease, the lack of randomized surgical studies, and the lack of a universally accepted and validated staging system make it difficult to reach consensus and establish stage-specific protocols. However, with strict criteria, subsets of patients can be identified who can benefit from aggressive cytoreductive surgical approaches, such as extrapleural pneumonectomy, and adjuvant chemoradiation protocols. Our experience with this type of protocol in carefully selected patients has resulted in increased median survival. The lack of cure in any of the published protocols demonstrates the need for new therapies and approaches for this disease.

Multimodality treatment of diffuse malignant pleural mesothelioma

Diffuse malignant pleural mesothelioma (DMPM) is a challenging disease in all of its aspects, from presentation and diagnosis to staging and treatment. Single-modality therapy was the initial approach to this disease. It generally has not been effective in changing the natural history of DMPM. As a result, multimodality regimens involving surgery with radiation, chemotherapy, or immunotherapy delivered regionally or systemically have been evaluated. Randomized controlled studies comparing various strategies are lacking and, thus, the debate continues regarding the effectiveness of different treatment approaches.

Survival after conservative (palliative) management of pleural malignant mesothelioma

BACKGROUND AND OBJECTIVES

Malignant mesothelioma is a lethal disease. Aggressive multimodality treatment protocols are reportedly associated with improved survival, but the apparent survival benefits may simply reflect patient selection and the variable natural history of this malignancy. Before embarking on our own protocol of experimental treatment for mesothelioma, we sought to identify important prognostic factors and document the survival of patients treated conservatively (with palliative intent only) in our region.

METHODS

We performed a retrospective review of all patients with a diagnosis of malignant mesothelioma seen at our center between 1987 and 1999. Since curative intent treatment had not been given, we assumed that measured survival would largely reflect the natural history of the malignancy.

RESULTS

There were 101 patients (80 males and 21 females). Mean age was 65 +/- 9.2 years. Symptoms of disease were present for a median time of 5 months before the diagnosis was established. The most common presenting symptoms were dyspnea (46 patients), chest pain (30 patients), and weight loss (22 patients). Sixty-eight patients (68%) had a history of asbestos exposure. Mesothelioma subtypes included epithelial (43 patients), sarcomatous (26 patients), mixed (19 patients), desmoplastic (4 patients), and unspecified (9 patients). All 101 patients were treated with palliative intent. Talc pleurodesis was performed in 70 patients. At the time of analysis, 90 patients had died and 11 remained alive. Median survival was 213 (95% CI 137-289) days. Survival for the three major histological subtypes was significantly different (log rank, P = 0.0016). Histological subtype (epithelial favorable) was the only significant independent prognostic factor (Cox proportional hazard regression, P = 0.0009).

CONCLUSIONS

Patients with epithelial mesothelioma survive longer than those with other histological subtypes. Conservatively managed patients with pleural malignant mesothelioma have a median survival of approximately 7 months. These data from conservatively treated patients can serve as baseline information for future studies of experimental treatments.

A phase II trial of surgical resection and adjuvant high-dose hemithoracic radiation for malignant pleural mesothelioma

BACKGROUND

Surgical resection of malignant pleural mesothelioma is reported to have up to an 80% rate of local recurrence. We performed a phase II trial of high-dose hemithoracic radiation after complete resection to determine feasibility and to estimate rates of local recurrence and survival.

METHODS

Patients were eligible if they had a resectable tumor, as determined by computed tomographic scanning, and adequate cardiopulmonary function for extrapleural pneumonectomy or pleurectomy/decortication. After complete resection, patients received hemithoracic radiation (54 Gy) and then were followed up with serial computed tomographic scanning.

RESULTS

From 1995 to 1998, 88 patients (73 men and 15 women; median age, 62.5 years) were entered into the study. The operations performed included 62 extrapleural pneumonectomies (70%) and 5 pleurectomies/decortications; procedures for exploration only were performed in 21 patients. Seven (7.9%) patients died postoperatively. Adjuvant radiation administered to 57 patients (54 undergoing extrapleural pneumonectomy and 3 undergoing pleurectomy/decortication) at a median dose of 54 Gy was well tolerated (grade 0-2 fatigue, esophagitis), except for one late esophageal fistula. The median survival was 33.8 months for stage I and II tumors but only 10 months for stage III and IV tumors (P =.04). For the patients undergoing extrapleural pneumonectomy, the sites of recurrence were locoregional in 2, locoregional and distant in 5, and distant only in 30.

CONCLUSION

Hemithoracic radiation after complete surgical resection at a dose not previously reported is feasible. This approach dramatically reduces local recurrence and is associated with prolonged survival for early-stage tumors. Stage III disease has a high risk of early distant relapse and should be considered for trials of systemic therapy added to this regimen of resection and radiation.

Intraoperative photodynamic therapy after pleuropneumonectomy in patients with malignant pleural mesothelioma: dose finding and toxicity results

OBJECTIVE

To determine the optimal administered dose of meta-tetrahydroxyphenylchlorin (mTHPC) for intraoperative photodynamic therapy (IPDT) in resected malignant pleural mesothelioma (MPM). The primary objective of this combination treatment was to improve local tumor control.

DESIGN

Phase I/II dose escalation study.

SETTING

Two Dutch cancer centers.

PATIENTS

The study included 28 patients (2 women, 26 men), with pathologically confirmed MPM. The mean age was 57 years (age range, 37 to 68 years), and the World Health Organization performance score was 0 to 1. Epithelial mesotheliomas were found in 17 patients, a sarcomatous mesothelioma was found in 1 patient, and mixed epithelial sarcomatous mesotheliomas were found in 10 patients.

METHODS

Patients were injected with 0.075 mg/kg (4 patients), 0.10 mg/kg (19 patients), or 0.15 mg/kg (5 patients) mTHPC 4 or 6 days before undergoing surgery and IPDT. Complete surgical resection (i.e., pleuropneumonectomy) was followed by integral illumination with monochromatic light of 652 nm (10 J/cm(2)). The real-time fluence rate measurements were performed using four isotropic detectors in the chest cavity to calculate the total light dose.

RESULTS

Dose-limiting toxicity was reached at the level of 0.15 mg/kg mTHPC. Three patients died in the perioperative period, and one death was directly related to photodynamic therapy. Real-time dosimetry identified 12 patients in whom additional illumination had to be given to the diaphragmatic sinuses, which were unavoidably shielded during integral illumination. In two patients, illumination was cancelled due to the insufficient resectability of the tumor. The median survival time for all 28 patients was 10 months. Local tumor control, 9 months after treatment, was achieved in 13 of the 26 patients treated with IPDT.

CONCLUSION

IPDT using mTHPC, combined with a pleuropneumonectomy, resulted in local control of disease in 50% of the treated cases. The considerable toxicity associated with the procedure, however, precludes its recommendation for widespread use. Stricter patient selection and improvements of the IPDT technique may reduce the toxicity.

Photodynamic therapy for mesothelioma

Multiple trials of traditional cancer therapies for malignant pleural mesothelioma (including surgery, radiation therapy, and chemotherapy) have not convincingly demonstrated that any one treatment is superior to supportive care alone. Although there have been reports of long-term survivors who were treated with aggressive surgery combined with radiation and aggressive multi-agent chemotherapeutic regimens, these patient populations are highly selected and results cannot be generalized to a larger population. Despite attempts to use aggressive multimodality therapies, disease recurs in most patients. Local failure in particular is a large part of the natural history of mesothelioma, especially after surgery alone. Therefore, one of the major considerations in the development of new treatments is the inclusion of aggressive local therapies. Photodynamic therapy (PDT), a local treatment modality, is being evaluated as an adjuvant therapy to surgical resection. Clinical use of PDT requires the use of a photosensitizing agent and light of a wavelength specific to the absorption characteristics of the sensitizer in the presence of oxygen. The treatment effect of PDT is superficial, mostly because of the limited depth of light absorption in tissues. Therefore, it is theoretically an ideal treatment for tissue surfaces and body cavities after surgical debulking procedures. One theoretical advantage of PDT is that it can be used to treat the lung surface after a pleurectomy; therefore, patients may be treated with a pleurectomy rather than with an extrapleural pneumonectomy. Several studies have evaluated the efficacy of PDT in the treatment of mesothelioma. Clinical studies have not proven convincingly that the use of PDT is superior to the use of other adjuvant therapies or to surgery alone. The advent of newer photosensitizers and improved laser technology has led to a renewed interest in evaluating PDT. Additional studies are necessary to determine the role of PDT in the treatment of mesothelioma.

Malignant pleural mesothelioma

Malignant pleural mesothelioma remains a difficult tumor to treat, much less cure. Currently, the best chance for long-term survival lies with early diagnosis and aggressive surgical extirpation, but given the typically long delay between the onset of symptoms and diagnosis, this is only possible with a high index of suspicion and an aggressive diagnosis workup. Early referral to a tertiary center experienced in the treatment of MPM may be important for several reasons: (1) decreased risk of tumor spread along multiple thoracenesis/biopsy tracts, (2) the availability of specialized pathologic assays for definitive diagnosis, (3) the availability of critical staging modalities (aggressive mediastinoscopy +/- thoracoscopy, MRI scans performed according to specific mesothelioma protocols, and perhaps PET scans), (4) surgical experience with pleurectomy/decortication and/or extrapleural pneumonectomy, that may decrease morbidity and mortality, and (5) the availability of novel adjuvant protocols. Single-modality therapy is unlikely to result in long-term survival. Aggressive surgery is required for optimal debulking, and extrapleural pneumonectomy may offer better local control compared with pleurectomy/ecortication. Delivery of optimal radiation schedules, which may involve large fractions as well as large total doses, is limited by the presence of nearby dose-limiting structures. Current chemotherapy is severely lacking in producing objective responses and improved survival although gemcitabine and IL-2 may be active agents to be combined with radiation and/or other agents. Hyperthermia, photodynamic therapy, intracavitary therapy, and gene therapy are all relatively new techniques under active investigation that should be supported by enrollment in on-going protocols. Predictably, many of these techniques provide greater benefit when used in the setting of adjuvant protocols or minimal residual disease, emphasizing the importance of multimodality therapy.

Malignant pleural mesothelioma

Despite innumerable trials of surgery, radiotherapy, and countless chemotherapeutic drugs, it is unclear whether any intervention has had a significant impact on more than a few highly selected patients with malignant pleural mesothelioma. Because most patients die of respiratory failure from extensive disease progression in the thorax, treatment usually includes attempts at local control. Unfortunately, radiotherapy is associated with significant complications in pleural mesothelioma, and surgery is feasible in only a small percentage of patients. Although there have been several single-institution reports of combined-modality therapy with extrapleural pneumonectomy, postoperative radiation, and chemotherapy in which prolonged survival has been observed, most patients with malignant pleural mesothelioma have locally advanced disease, advanced age, or comorbid medical illnesses that preclude aggressive surgery. Therefore, the use of a systemic anticancer agent is the only treatment option for most patients with malignant pleural mesothelioma. Evaluation of effective chemotherapy regimens for this disease has been hampered by many factors. Because mesothelioma is an uncommon malignancy, most studies have enrolled small numbers of patients, and few trials have been randomized. The disease is heterogeneous, yet until recently there was no single staging system that could reliably predict survival, nor is there a universally accepted set of prognostic criteria for selecting a uniform group of patients. Response assessment has been limited by the inherent difficulties of reproducibly measuring pleural-based disease. The real impact of systemic chemotherapy on the natural history of malignant mesothelioma is still uncertain because phase III trials comparing chemotherapy with best supportive care have not yet been completed. Although nearly every class of cytotoxic agent has been evaluated in mesothelioma, response rates of greater than 20% have not been consistently demonstrated for any drug. The most active drug classes are the antifolates, the anthracyclines, and the platinums. Doxorubicin has historically been considered the gold-standard chemotherapy, although its true response rate is likely only 15%. The most active commercially available drug for mesothelioma so far appears to be gemcitabine. Although gemcitabine has a limited role as a single agent, it is quite active in combination with a platinating agent. The impressive 48% response rate reported for the combination of gemcitabine with cisplatin in a single phase II study has made this regimen the new standard of care for off-protocol treatment of this disease, although this trial still requires validation. With the recent introduction of several new agents with definite activity in this disease, the therapeutic nihilism previously associated with malignant pleural mesothelioma is gradually being replaced by a cautious optimism. Early trials of angiogenesis inhibitors, gene therapy, and vaccines offer additional avenues for treatment. As we begin to incorporate these active new drugs with each other and in adjuvant and neoadjuvant treatment regimens, there is reason to believe that superior results for patients with malignant pleural mesothelioma can be achieved in the near future.

Management of malignant pleural mesothelioma: a critical review

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

Mesothelioma: new concepts in diagnosis and management

Malignant pleural mesothelioma is an uncommon, but no longer rare, cancer that is frequently difficult to diagnose and poorly responsive to therapy. Because of the difficulties distinguishing mesothelioma from metastatic adenocarcinoma and reactive pleural inflammation, thoracoscopy or open lung biopsy are usually required to obtain adequate samples for pathologic evaluation. Staging of mesothelioma remains a controversial area. Because none of the six staging systems used in the past was found to be predictive, a TNM-based staging system was recently proposed and is awaiting universal acceptance. Generally perceived as a death sentence, this cancer is associated with a median survival of 9 months from the time of diagnosis in most series, but newer therapeutic strategies show promise for improved and even long-term survival in select cases. Randomized trials are awaited to determine if the improvements in survival reported are not simply due to patient selection.

Emerging translational therapies for mesothelioma

Malignant pleural mesothelioma remains a therapeutic and diagnostic problem. Translational mechanisms for treatment of the disease are emerging from newly learned characteristics of the tumor on a molecular, cellular, and extracellular basis. Although slow to reach the clinical arena, these potential strategies do show proof of principle in the in vitro and in vivo settings, and some, including adenoviral molecular chemotherapy, have completed phase I testing. This review describes the rationale and status of these newer treatment ideas.

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.

Pleural mesothelioma

The increasing incidence of malignant pleural mesothelioma (MPM), better knowledge of its pathogenesis with a strong implication of asbestos fibers, and some promising therapeutic results have led to a new interest in the management of patients with this disease. The diagnosis of MPM is easier because of new immunohistochemical markers that recognize the mesothelial cells with good specificity and sensitivity on pleural biopsy samples ideally obtained by thoracoscopy. Moreover, this endoscopic procedure allows the physician to make the diagnosis of MPM at an early stage, which is the key of the therapeutic management of this disease. If radiotherapy is necessary in preventing the malignant seeding after pleural procedures in patients, the lack of comparative studies did not show the superiority of a given treatment against another. A new international staging of the disease, however, allows physicians to discriminate several groups of patients for such comparative studies--in particular, for testing the efficacy of intrapleural therapy, e.g., cytokines--for early-stage MPM and multimodal management, i.e., extrapleural pneumonectomy, radiotherapy, and chemotherapy for more advanced diseases, has led to prolonged survival in carefully selected patients. To reach this target, all patients must be enrolled in protocols. The usual pessimism for the management of patients with malignant pleural mesothelioma is over.

Resection margins, extrapleural nodal status, and cell type determine postoperative long-term survival in trimodality therapy of malignant pleural mesothelioma: results in 183 patients

OBJECTIVES

Our aim was to identify prognostic variables for long-term postoperative survival in trimodality management of malignant pleural mesothelioma.

METHODS

From 1980 to 1997, 183 patients underwent extrapleural pneumonectomy followed by adjuvant chemotherapy and radiotherapy.

RESULTS

Forty-three women and 140 men (age range 31-76 years) had a median follow-up of 13 months. The perioperative mortality rate was 3.8% (7 deaths) and the morbidity, 50%. Survival in the 176 remaining patients was 38% at 2 years and 15% at 5 years (median 19 months). Univariate analysis identified 3 prognostic variables associated with improved survival: epithelial cell type (52% 2-year survival, 21% 5-year survival, 26-month median survival; P =.0001), negative resection margins (44% at 2 years, 25% at 5 years, median 23 months; P =.02), and extrapleural nodes without metastases (42% at 2 years, 17% at 5 years, median 21 months; P =.004). Using the Cox proportional hazards, the relative risk of death was calculated for nonepithelial cell type (OR 3.0, CI 2.0-4.5; P <.0001), positive resection margins (OR 1.7, CI 1.2-2.6; P =.0082), and metastatic extrapleural nodes (OR 2.0, CI 1.3-3.2; P =.0026). Thirty-one patients with 3 positive variables had the best survival (68% 2-year survival, 46% 5-year survival, median 51 months; P =.013). A previously published staging system using these variables stratified survival (P <.05).

CONCLUSIONS

(1) Multimodality therapy including extrapleural pneumonectomy is feasible in selected patients with malignant pleural mesotheliomas, (2) pre-resectional evaluation of extrapleural nodes may select patients for radical therapy, (3) microscopic resection margins affect long-term survival, highlighting the need for further investigation of locoregional control, and (4) patients with epithelial, margin-negative, extrapleural node-negative resection had extended survival.

Operation and photodynamic therapy for pleural mesothelioma: 6-year follow-up

BACKGROUND

Conventional therapy for pleural mesothelioma has met with disappointing results.

METHODS

From 1991 to 1996, 40 patients with malignant pleural mesothelioma were treated with surgical resection followed by immediate intracavitary photodynamic therapy.

RESULTS

The series included 9 women and 31 men with a mean age of 60 years. Morbidity and treatment-related mortality rates for the entire series, pleurectomy, and extrapleural pneumonectomy were 45% and 7.5%, 39% and 3.6%, and 71% and 28.6%, respectively. Median survival and the estimated 2-year survival rate for the entire series, stages I and II patients (n = 13), and stages III and IV patients (n = 24) were 15 months and 23%, 36 months and 61%, and 10 months and 0%, respectively. Multivariate analysis identified stage, length of hospital stay, photodynamic therapy dose, and nodal status as independent prognostic indicators for survival.

CONCLUSIONS

Surgical intervention and photodynamic therapy offer good survival results in patients with stage I or II pleural mesothelioma. For patients in stage III or IV, better treatment modalities need to be developed. Improvements in early detection and preoperative staging are necessary for proper patient selection for treatment.

Preoperative tumor volume is associated with outcome in malignant pleural mesothelioma

OBJECTIVES

Our objective was to analyze the impact of preoperative and postresection solid tumor volumes on outcomes in 47 of 48 consecutive patients undergoing resection for malignant pleural mesothelioma who were treated prospectively and randomized to photodynamic therapy or no photodynamic therapy.

METHODS

From July 1993 to June 1996, 48 patients with malignant pleural mesothelioma had cytoreductive debulking to 5 mm or less residual tumor by extrapleural pneumonectomy (n = 25) or pleurectomy/decortication (n = 23). Three-dimensional computed tomographic reconstructions of preresection and postresection solid tumor were prospectively performed and the disease was staged postoperatively according to the new International Mesothelioma Interest Group staging.

RESULTS

Median survival for all patients is 14.4 months (extrapleural pneumonectomy, 11 months; pleurectomy/decortication, 22 months; p2 = 0.07). Median survival for preoperative volume less than 100 was 22 months versus 11 months if more than 100 cc, p2 = 0.03. Median survival for postoperative volume less than 9 cc was 25 months versus 9 months if more than 9 cc, p2 = 0.0002. Thirty-two of forty-seven (68%) had positive N1 or N2 nodes. Tumor volumes associated with negative nodes were significantly smaller (median 51 cc) than those with positive nodes (median 166 cc, p2 = 0.01). Progressively higher stage was associated with higher median preoperative volume: stage I, 4 cc; stage II, 94 cc; stage III, 143 cc; stage IV, 505 cc; p2 = 0.007 for stage I versus II versus III versus IV. Patients with preoperative tumor volumes greater than 52 cc had shorter progression-free intervals (8 months) than those 51 cc or less (11 months; p2 = 0.02).

CONCLUSIONS

Preresection tumor volume is representative of T status in malignant pleural mesothelioma and can predict overall and progression-free survival, as well as postoperative stage. Large volumes are associated with nodal spread, and postresection residual tumor burden may predict outcome.