Ionizing radiation: a risk factor for mesothelioma

Diffuse Pleural Mesotheliomas with Genomic Near-Haploidization: A Newly Recognized Subset with Distinct Clinical, Histologic, and Molecular Features

PURPOSE

Diffuse pleural mesotheliomas (DPM) with genomic near-haploidization (GNH) represent a novel subtype first recognized by The Cancer Genome Atlas project; however, its clinicopathologic and molecular features remain poorly defined.

EXPERIMENTAL DESIGN

We analyzed clinical genomic profiling data from 290 patients with DPM using the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) assay. Allele-specific copy number analysis was performed using the Fraction and Allele-Specific Copy Number Estimates from Tumor Sequencing (FACETS) algorithm.

RESULTS

A total of 210 patients were evaluable for loss of heterozygosity (LOH) analysis using FACETS from MSK-IMPACT tumor:normal sequencing data. In this cohort, GNH, defined as LOH across >80% of the genome, was detected in 10 cases (4.8%). Compared with non-GNH tumors, GNH DPMs were associated with younger age and less frequent self-reported history of occupational asbestos exposure. Histologically, GNH DPMs were enriched in biphasic subtype (80% vs. 14.5%) and showed abundant tumor-infiltrating lymphocytes (TILs). Genomic analysis revealed a higher frequency of TP53 alterations, whereas SETDB1 mutations were present in nearly all and only in this subset. The clinicopathologic and molecular findings were further validated in a separate cohort. Despite the younger age, patients with GNH DPMs had a shorter overall survival (10.9 vs. 25.4 months, P = 0.004); the poor prognostic impact of GNH remained significant after controlling for biphasic histology. Of three patients with GNH DPMs who received immune checkpoint blockade, two achieved a clinician-assessed partial response.

CONCLUSIONS

GNH defines an aggressive subtype of mainly biphasic DPMs in younger patients with recurrent alterations in SETDB1 and TP53. The enrichment in biphasic histology and TILs, together with our preliminary immune checkpoint blockade response data and anecdotal clinical trial data, suggests that further evaluation of immunotherapy may be warranted in this subset.

Health Effects of Occupational and Environmental Exposures to Nuclear Power Plants: A Meta-Analysis and Meta-Regression

PURPOSE OF REVIEW

Numerous epidemiological studies have shown increased health risks among workers and residents living near nuclear power plants exposed to radiation levels meeting regulatory dose limits. This study aimed to evaluate the association between radiation exposure and disease risks among these populations exposed to radiation levels meeting the current regulatory dose limits.

RECENT FINDINGS

We searched four databases (Cochrane Library, PubMed, ScienceDirect, and Web of Science) for studies published before August 2023, screened eligible studies (inclusion and exclusion criteria based on population, exposure, comparator, and outcome framework), and collected data on exposure indicators and disease risks. We applied random-effects models of meta-analysis to estimate the pooled effects and meta-regression to assess the dose-response relationship (radiation dose rate for workers and distance for residents). We identified 47 studies, 13 with worker and 34 with resident samples, covering 175 nuclear power plants from 17 countries, encompassing samples of 480,623 workers and 7,530,886 residents. Workers had a significantly lower risk for all-cancer and a significantly higher risk for mesothelioma. Residents had significantly higher risks for all-cancer, thyroid cancer, and leukemia. Notably, children under 5 years old showed the highest risk for all-cancer. Our meta-regression showed a significantly positive dose-response relationship between cumulative dose of radiation exposure and risk for circulatory disease among workers. Our findings demonstrated higher risks for mesothelioma for workers and all-cancer, thyroid cancer, and leukemia for residents exposed to low-dose radiation from nuclear power plants. Some included studies did not adjust for cancer risk confounders, which could overestimate the association between radiation exposure and cancer risk and increase the risk of bias.

Occupational exposure to asbestos in the steel industry (1972-2006)

BACKGROUND

Historically, the use of asbestos in steelmaking has been limited to a few applications. Due to its physical and chemical properties, asbestos was not necessary or suitable for most purposes in a steel mill. The few applications where asbestos were used (i.e., certain gaskets, brakes, protective cloth, refractory materials, insulation materials, and hot top products) were replaced by alternative materials as they became available.

OBJECTIVE

We discuss historical uses of asbestos in steel manufacturing and the associated airborne asbestos concentrations collected at sixteen U. S. Steel facilities between 1972 and 2006.

METHODS

A total of 495 personal airborne asbestos samples from the U. S. Steel industrial hygiene records were analyzed across four time periods corresponding to changes in the OSHA permissible exposure limit (PEL) for asbestos. 68% of the samples (n = 337) were considered representative of an employee's workday. The remaining samples (n = 158) represented task samples. Samples were grouped by facility, department, and job category within the four time periods.

RESULTS

The average fiber concentrations measured for each facility and department over time were below the contemporaneous OSHA PEL. The mean representative workday asbestos air concentration from 1972 and 1975 was 1.09 f/cc. The mean representative workday concentration decreased to 0.13 f/cc between 1976 and 1985, then decreased again to 0.02 f/cc between 1986 and 1993 and 0.03 f/cc between 1994 and 2006. For task samples, the mean air concentration from 1972 to 1975 was 3.29 f/cc. The mean task sample concentration decreased to 0.48 f/cc between 1976 and 1985, then decreased again to 0.01 f/cc between 1986 and 1993 and 0.03 f/cc between 1994 and 2006. Only eleven out of the 495 samples (2.2%), for both task and representative workday samples, were in exceedance of the contemporaneous PEL(as an 8-hour TWA), ten of which occurred prior to 1978. Eight of these eleven PEL exceeding samples were task samples. Of the remaining three representative workday samples, two had unknown sampling times.

IMPACT

This paper presents an analysis of all the available personal sampling data for airborne asbestos across 16 facilities of the U. S. Steel Corporation between 1972 and 2006. This dataset has previously never been publicly shared or analyzed. It represents one of the more complete industrial hygiene datasets from a corporation to be presented in a scientific journal and, due to the similarities in the processes at each mill, it should reflect analogous exposures throughout the steelmaking industry in the United States. One of the benefits of presenting these data is that it also provides insight into where asbestos-containing materials (ACMs) were used in the steel making process. This is just one example of a large firm that released information that had previously remained in file cabinets for decades. We believe that another benefit of publishing this paper is that it may encourage the largest firms in industry to assemble and analyze their industrial hygiene data to benefit the occupational hygiene, medical, and epidemiology communities. This can support future epidemiology studies and improve the design of future industrial hygiene programs.

An Overview of Cancer in Djibouti: Current Status, Therapeutic Approaches, and Promising Endeavors in Local Essential Oil Treatment

Djibouti, a developing economy, grapples with significant socioeconomic obstacles and the prevalence of infectious pathologies, including certain forms of neoplasms. These challenges are exacerbated by limited access to affordable medical technologies for diagnosis, coupled with a lack of preventive interventions, particularly in disadvantaged areas. The attention devoted to local phytotherapeutic treatments underscores the uniqueness of Djibouti's flora, resulting from its distinctive geographical position. International focus specifically centers on harnessing this potential as a valuable resource, emphasizing the phytoconstituents used to counter pathologies, notably carcinomas. This comprehensive overview covers a broad spectrum, commencing with an examination of the current state of knowledge, namely an in-depth investigation of oncological risk factors. Essential elements of control are subsequently studied, highlighting the fundamental prerequisites for effective management. The significance of dietary habits in cancer prevention and support is explored in depth, while traditional methods are examined, highlighting the cultural significance of indigenous essential oil therapies and encouraging further research based on the promising results.

Mechanisms and shapes of causal exposure-response functions for asbestos in mesotheliomas and lung cancers

This paper summarizes recent insights into causal biological mechanisms underlying the carcinogenicity of asbestos. It addresses their implications for the shapes of exposure-response curves and considers recent epidemiologic trends in malignant mesotheliomas (MMs) and lung fiber burden studies. Since the commercial amphiboles crocidolite and amosite pose the highest risk of MMs and contain high levels of iron, endogenous and exogenous pathways of iron injury and repair are discussed. Some practical implications of recent developments are that: (1) Asbestos-cancer exposure-response relationships should be expected to have non-zero background rates; (2) Evidence from inflammation biology and other sources suggests that there are exposure concentration thresholds below which exposures do not increase inflammasome-mediated inflammation or resulting inflammation-mediated cancer risks above background risk rates; and (3) The size of the suggested exposure concentration threshold depends on both the detailed time patterns of exposure on a time scale of hours to days and also on the composition of asbestos fibers in terms of their physiochemical properties. These conclusions are supported by complementary strands of evidence including biomathematical modeling, cell biology and biochemistry of asbestos-cell interactions in vitro and in vivo, lung fiber burden analyses and epidemiology showing trends in human exposures and MM rates.

Current causes of mesothelioma: how has the asbestos ban changed the perspective?

The association of mesothelioma, a lethal lung disease, with asbestos has led to an absolute ban on asbestos in at least 55 countries worldwide. The purpose of this paper is to review residual exposure to asbestos as well as other emerging causes of mesothelioma outside asbestos. The review provides detailed description of asbestos minerals, their geographical locations, mesothelioma in these areas, as well as contemporary possible sources of asbestos exposure. Second, we examine other emerging causes of mesothelioma including: ionizing radiation as the second most important risk factor after asbestos, particularly relevant to patients undergoing radiotherapy, third, carbon nanotubes which are under investigation and fourth, Simian virus 40. In the case of asbestos per se, the greatest risk is from occupational exposure during mining and subsequent processing. Of the non-occupational exposures, environmental exposure is most serious, followed by exposure from indoor asbestos minerals and secondary familial exposure. Overall, asbestos is still a major risk factor, but alternative causes should not be neglected, especially in young people, in women and those with a history of radiotherapy or living in high-risk locations.

Activation of Adaptive and Innate Immune Cells via Localized IL2 Cytokine Factories Eradicates Mesothelioma Tumors

PURPOSE

IL2 immunotherapy has the potential to elicit immune-mediated tumor lysis via activation of effector immune cells, but clinical utility is limited due to pharmacokinetic challenges as well as vascular leak syndrome and other life-threatening toxicities experienced by patients. We developed a safe and clinically translatable localized IL2 delivery system to boost the potency of therapy while minimizing systemic cytokine exposure.

EXPERIMENTAL DESIGN

We evaluated the therapeutic efficacy of IL2 cytokine factories in a mouse model of malignant mesothelioma. Changes in immune populations were analyzed using time-of-flight mass cytometry (CyTOF), and the safety and translatability of the platform were evaluated using complete blood counts and serum chemistry analysis.

RESULTS

IL2 cytokine factories enabled 150× higher IL2 concentrations in the local compartment with limited leakage into the systemic circulation. AB1 tumor burden was reduced by 80% after 1 week of monotherapy treatment, and 7 of 7 of animals exhibited tumor eradication without recurrence when IL2 cytokine factories were combined with anti-programmed cell death protein 1 (aPD1). Furthermore, CyTOF analysis showed an increase in CD69+CD44+ and CD69-CD44+CD62L- T cells, reduction of CD86-PD-L1- M2-like macrophages, and a corresponding increase in CD86+PD-L1+ M1-like macrophages and MHC-II+ dendritic cells after treatment. Finally, blood chemistry ranges in rodents demonstrated the safety of cytokine factory treatment and reinforced its potential for clinical use.

CONCLUSIONS

IL2 cytokine factories led to the eradication of aggressive mouse malignant mesothelioma tumors and protection from tumor recurrence, and increased the therapeutic efficacy of aPD1 checkpoint therapy. This study provides support for the clinical evaluation of this IL2-based delivery system. See related commentary by Palanki et al., p. 5010.

Global magnitude and temporal trend of mesothelioma burden along with the contribution of occupational asbestos exposure in 204 countries and territories from 1990 to 2019: Results from the Global Burden of Disease Study 2019

Understanding the burden of mesothelioma with the contribution of occupational asbestos exposure globally provides essential foundations for cancer control, policy decisions and resource allocation. Globally, 34,511 incident cases, 29,251 deaths and 668,104 disability-adjusted life years (DALYs) of mesothelioma were estimated in 2019. The age-standardized rates of incidence, mortality and DALYs all showed a slightly declining trend over the past 30 years, but the latest absolute number of mesothelioma burden almost doubled since 1990. The burden rate decreased among the population aged under 70 years, but increased among the population aged over 80 years, especially in the High socio-demographic index (SDI) region. The burden rate of mesothelioma attributable to asbestos exposure was positively associated with SDI at the national level. This study depicted a continuous increase in mesothelioma burden globally over the past 30 years. Controlling occupational asbestos exposure will reduce the mesothelioma burden, especially for higher SDI regions.

Silencing VDAC1 to Treat Mesothelioma Cancer: Tumor Reprograming and Altering Tumor Hallmarks

Mesothelioma, an aggressive cancer with a poor prognosis, is linked to asbestos exposure. However, carbon nanotubes found in materials we are exposed to daily can cause mesothelioma cancer. Cancer cells reprogram their metabolism to support increased biosynthetic and energy demands required for their growth and motility. Here, we examined the effects of silencing the expression of the voltage-dependent anion channel 1 (VDAC1), controlling the metabolic and energetic crosstalk between mitochondria and the rest of the cell. We demonstrate that VDAC1 is overexpressed in mesothelioma patients; its levels increase with disease stage and are associated with low survival rates. Silencing VDAC1 expression using a specific siRNA identifying both mouse and human VDAC1 (si-m/hVDAC1-B) inhibits cell proliferation of mesothelioma cancer cells. Treatment of xenografts of human-derived H226 cells or mouse-derived AB1 cells with si-m/hVDAC1-B inhibited tumor growth and caused metabolism reprogramming, as reflected in the decreased expression of metabolism-related proteins, including glycolytic and tricarboxylic acid (-)cycle enzymes and the ATP-synthesizing enzyme. In addition, tumors depleted of VDAC1 showed altered microenvironments and inflammation, both associated with cancer progression. Finally, tumor VDAC1 silencing also eliminated cancer stem cells and induced cell differentiation to normal-like cells. The results show that silencing VDAC1 expression leads to reprogrammed metabolism and to multiple effects from tumor growth inhibition to modulation of the tumor microenvironment and inflammation, inducing differentiation of malignant cells. Thus, silencing VDAC1 is a potential therapeutic approach to treating mesothelioma.

Relationship between exposure to ionizing radiation and mesothelioma risk: A systematic review of the scientific literature and meta-analysis

BACKGROUND

Ionizing radiation and mesothelioma have been examined among personnel employed in nuclear power plant and patients treated by external beam radiation therapy (EBRT). The association is still controversial; the purpose of this review is to summarize the scientific evidence published in the literature regarding the relationship between ionizing radiation and incidence of mesothelioma and, if possible, estimating strongness of the association by meta-analysis of extracted data.

METHODS

Articles included in the systematic review were retrieved by searching among the three main scientific databases: PubMed, Scopus, and Embase. The literature search was conducted in June 2021. A meta-analysis of random effects was conducted, stratified by exposure (EBRT, occupational exposure). The heterogeneity of the summary relative risks (RRs) was assessed using I2  statistics. Publication bias was evaluated graphically through the funnel plot.

FINDINGS

The exposure to ionizing radiation could be a risk factor for mesothelioma: both for exposure to high doses for short periods (EBRT) (RR of 3.34 [95% confidence interval, CI 1.24-8.99]) and for exposure to low doses for a prolonged duration (exposure working) (RR of 3.57 [95% CI 2.16-5.89]).

CONCLUSIONS

Despite the low number of mesotheliomas in the general population, the steadily increased risk among individuals exposed to radiation is still worth considering.

A critical review of the 2020 EPA risk assessment for chrysotile and its many shortcomings

From 2018 to 2020, the United States Environmental Protection Agency (EPA) performed a risk evaluation of chrysotile asbestos to evaluate the hazards of asbestos-containing products (e.g. encapsulated products), including brakes and gaskets, allegedly currently sold in the United States. During the public review period, the EPA received more than 100 letters commenting on the proposed risk evaluation. The Science Advisory Committee on Chemicals (SACC), which peer reviewed the document, asked approximately 100 questions of the EPA that they expected to be addressed prior to publication of the final version of the risk assessment on 30 December 2020. After careful analysis, the authors of this manuscript found many significant scientific shortcomings in both the EPA's draft and final versions of the chrysotile risk evaluation. First, the EPA provided insufficient evidence regarding the current number of chrysotile-containing brakes and gaskets being sold in the United States, which influences the need for regulatory oversight. Second, the Agency did not give adequate consideration to the more than 200 air samples detailed in the published literature of auto mechanics who changed brakes in the 1970-1989 era. Third, the Agency did not consider more than 15 epidemiology studies indicating that exposures to encapsulated chrysotile asbestos in brakes and gaskets, which were generally in commerce from approximately 1950-1985, did not increase the incidence of any asbestos-related disease. Fourth, the concern about chrysotile asbestos being a mesothelioma hazard was based on populations in two facilities where mixed exposure to chrysotile and commercial amphibole asbestos (amosite and crocidolite) occurred. All 8 cases of pleural cancer and mesothelioma in the examined populations arose in facilities where amphiboles were present. It was therefore inappropriate to rely on these cohorts to predict the health risks of exposure to short fiber chrysotile, especially of those fibers filled with phenolic resins. Fifth, the suggested inhalation unit risk (IUR) for chrysotile asbestos was far too high since it was not markedly different than for amosite, despite the fact that the amphiboles are a far more potent carcinogen. Sixth, the approach to low dose modeling was not the most appropriate one in several respects, but, without question, it should have accounted for the background rate of mesothelioma in the general population. Just one month after this assessment was published, the National Academies of Science notified the EPA that the Agency's systematic review process was flawed. The result of the EPA's chrysotile asbestos risk evaluation is that society can expect dozens of years of scientifically unwarranted litigation. Due to an aging population and because some fraction of the population is naturally predisposed to mesothelioma given the presence of various genetic mutations in DNA repair mechanisms (e.g. BAP1 and others), the vast majority of mesotheliomas in the post-2035 era are expected to be spontaneous and unrelated in any way to exposure to asbestos. Due to the EPA's analysis, it is our belief that those who handled brakes and gaskets in the post-1985 era may now believe that those exposures were the cause of their mesothelioma, when a risk assessment based on the scientific weight of evidence would indicate otherwise.

Current evidence and future perspectives of immune-checkpoint inhibitors in unresectable malignant pleural mesothelioma

Platinum-based chemotherapy is commonly used as the standard first-line treatment for unresectable malignant pleural mesothelioma (MPM). However, in recent times, immune-checkpoint inhibitors (ICIs) have led to a paradigm shift. Herein, we review relevant literature and ongoing trials of ICIs used as both first-line and salvage therapies. Specifically, in the Japanese single-arm, phase II trial, the MERIT trial, nivolumab, an antiprogrammed cell death 1 (PD-1) antibody showed favorable efficacy when used as a salvage therapy. Currently, multiple ICI monotherapy or combination therapy trials have been conducted, which could provide further evidence. Among available ICIs, the anti-PD-1 antibody is promising for unresectable MPM, despite the limited efficacy of anti-CTLA4 monotherapy. Ongoing studies will further confirm the potential efficacy of ICIs for MPM, as observed across other malignancies. It is also crucial to identify any clinically useful predictive biomarkers that could reveal ICIs with maximal effects in MPM.

Overexpression of microRNA‑486 affects the proliferation and chemosensitivity of mesothelioma cell lines by targeting PIM1

Dysregulated levels of microRNAs (miRNAs or miRs), involved in oncogenic pathways, have been proposed to contribute to the aggressiveness of malignant pleural mesothelioma (MPM). Previous studies have highlighted the downregulation of miRNA miR-486-5p in patients with mesothelioma and the introduction of miRNA mimics to restore their reduced or absent functionality in cancer cells is considered an important therapeutic strategy. The aim of the present study was to evaluate the mechanisms through which miRNAs may influence the functions, proliferation and sensitivity to cisplatin of MPM cells. In the present study, a miR-486-5p mimic was transfected into the H2052 and H28 MPM cell lines, and cell viability, proliferation, apoptosis and mitochondrial membrane potential were monitored. miR-486-5p overexpression led to a clear impairment of cell proliferation, targeting CDK4 and attenuating cell cycle progression. In addition, transfection with miR-486-5p mimic negatively regulated the release of inflammatory factors and the expression of Provirus integration site for Moloney murine leukaemia virus 1 (PIM1). The sensitivity of the cells to cisplatin was enhanced by enhancing the apoptotic effects of the drug and impairing mitochondrial function. On the whole, the present study demonstrates that miR-486-5p may play an important role in MPM treatment by targeting multiple pathways involved in tumour development and progression. These activities may be mostly related to the downregulation of PIM1, a crucial regulator of cell survival and proliferation. Furthermore, these results provide support for the combined use of miR-486-5p with chemotherapy as a therapeutic strategy for MPM.

The Association between Malignant Pleural Mesothelioma and Thoracic Radiation Therapy for Hodgkin's Lymphoma: The First Case Report in Japan

Malignant pleural mesothelioma (MPM) is mostly observed in patients with a history of asbestos exposure. Although other causes are rare, there are several reports of MPM induced by therapeutic radiation, mainly in Europe and North America. However, no such case has been reported in Japan. We herein report a 50-year-old Japanese woman who developed MPM 25 years after thoracic radiation therapy for Hodgkin's lymphoma. The patient had no history of exposure to asbestos; therefore, her history of radiation therapy was considered to be the cause of MPM. Clinicians should consider secondary MPM in patients with a history of thoracic radiation therapy.

Malignant Peritoneal Mesothelioma Arising in Young Adults With Long-standing Indwelling Intra-abdominal Shunt Catheters

Only 50% to 70% of patients with mesothelioma report asbestos exposure. Other exposures (eg, radiation) play a role in some cases, but some patients have no obvious cause. We describe a series of patients with long-standing indwelling intra-abdominal shunt catheters who developed malignant peritoneal mesothelioma, suggesting a novel association. We identified 7 patients who had shunts and subsequently developed mesothelioma (5 women; median age: 31 y, range: 18 to 45 y). Clinical history and pathology materials were reviewed, and RNA sequencing was performed. Clinical presentations varied; 6 patients had hydrocephalus and a ventriculoperitoneal shunt, and 1 patient had portal hypertension and a portoatrial shunt. The median duration of shunt therapy in 5 cases was 29 years (range: 12 to 35 y); the remaining 2 patients also had shunts for many years, but specific details were unavailable. Two patients had radiotherapy for malignancies in childhood. One had an alleged exposure to asbestos and 1 had prior exposure to talc. The rest had no known risk factors. Histologically, all tumors were purely epithelioid. Treatments included surgical debulking, chemotherapy, and palliative care. All 7 died of disease (median survival: 7 mo, range: 1 to 18 mo). Molecular testing showed loss of NF2 and CDKN2A/B and a BAP1 mutation in 1 case, and no genomic alterations associated with mesothelioma in 2 cases. Peritoneal mesothelioma may represent a complication of long-standing indwelling shunt catheters. The mechanism is unknown, but chronic peritoneal irritation may play a role. Albeit rare, mesothelioma should be considered in patients with a shunt who present with new ascites.

Challenges in lung and thoracic pathology: molecular advances in the classification of pleural mesotheliomas

The diagnosis and classification of malignant pleural mesothelioma (MPM) is extremely challenging; obtaining an accurate histopathological diagnosis of the different types and subtypes requires expert assessment and suitable biopsies that are not always available, which can leave doctors uncertain about the patient's diagnosis, sometimes resulting in a delay in the start of treatment. In this review, we discuss recent major advances in the molecular characterisation of MPM and their implications for histological classification. We detail what is known of the molecular landscape of MPM at the genomic, transcriptomic, and epigenomic levels, describe the similarities and dissimilarities of the multiple molecular classifications that have been proposed, and provide an overview of the current state of knowledge regarding inter- and intra-tumour heterogeneity. We also highlight the current gaps in knowledge and how addressing them would benefit classification, as well as the patients in general.

Clinical Features in Patients With Malignant Pleural Mesothelioma With 5-Year Survival and Evaluation of Original Diagnoses

INTRODUCTION

Malignant pleural mesothelioma (MPM) is a fatal malignancy strongly associated with previous asbestos exposure. Overall survival remains dismal, partly owing to poor response to available treatment. The aims of this study were to evaluate diagnostic accuracy in a group of patients with MPM with an unusually long survival time and to assess the factors related to this prolonged survival.

MATERIALS AND METHODS

Forty-three patients with overall survival exceeding 5 years were accepted to the long-term survivor (LTS) group, and these patients were compared with 84 patients with epithelial MPM. Data were collected from various national registries and electronic medical records. In addition, all available histopathologic diagnostic samples and computed tomography studies were re-evaluated by experienced specialists.

RESULTS

Our study showed a good diagnostic accuracy, with only 1 (0.5%) patient having an incorrect MPM diagnosis. Two (0.9%) localized malignant mesotheliomas and 2 (0.9%) well-differentiated papillary mesotheliomas were also found. LTS patients were younger, more frequently female, had a better performance status at time of diagnosis, and had less evidence of prior asbestos exposure. In multivariate analysis, we showed tumor size, Eastern Cooperative Oncology Group performance status, and first-line treatment (both surgery and chemotherapy) to be associated with survival time.

CONCLUSION

We confirmed the diagnosis of MPM in an overwhelming majority of patients in the LTS group. An epithelial subtype of MPM behaving clinically more indolently seems to exist, but further tumor and genetic characterization is needed. The prolonged survival time is most likely explained by a combination of tumor-, patient-, and treatment-related factors.

Circulating Epigenetic Biomarkers in Malignant Pleural Mesothelioma: State of the Art and critical Evaluation

Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer, which originates from the mesothelial cells of the pleura and is associated with asbestos exposure. In light of its aggressive nature, late diagnosis and dismal prognosis, there is an urgent need for identification of biomarkers in easily accessible samples (such as blood) for early diagnosis of MPM. In the last 10 years, epigenetic markers, such as DNA methylation and microRNAs (miRNAs), have gained popularity as possible early diagnostic and prognostic biomarkers in cancer research. The aim of this review is to provide a critical analysis of the current evidences on circulating epigenetic biomarkers for MPM and on their translational potential to the clinical practice for early diagnosis and for prognosis.

Mesothelioma: Scientific clues for prevention, diagnosis, and therapy

Mesothelioma affects mostly older individuals who have been occupationally exposed to asbestos. The global mesothelioma incidence and mortality rates are unknown, because data are not available from developing countries that continue to use large amounts of asbestos. The incidence rate of mesothelioma has decreased in Australia, the United States, and Western Europe, where the use of asbestos was banned or strictly regulated in the 1970s and 1980s, demonstrating the value of these preventive measures. However, in these same countries, the overall number of deaths from mesothelioma has not decreased as the size of the population and the percentage of old people have increased. Moreover, hotspots of mesothelioma may occur when carcinogenic fibers that are present in the environment are disturbed as rural areas are being developed. Novel immunohistochemical and molecular markers have improved the accuracy of diagnosis; however, about 14% (high-resource countries) to 50% (developing countries) of mesothelioma diagnoses are incorrect, resulting in inadequate treatment and complicating epidemiological studies. The discovery that germline BRCA1-asssociated protein 1 (BAP1) mutations cause mesothelioma and other cancers (BAP1 cancer syndrome) elucidated some of the key pathogenic mechanisms, and treatments targeting these molecular mechanisms and/or modulating the immune response are being tested. The role of surgery in pleural mesothelioma is controversial as it is difficult to predict who will benefit from aggressive management, even when local therapies are added to existing or novel systemic treatments. Treatment outcomes are improving, however, for peritoneal mesothelioma. Multidisciplinary international collaboration will be necessary to improve prevention, early detection, and treatment.

Mesothelioma mortality within two radiation monitored occupational cohorts

Purpose: The risk of mesothelioma, including cancers of the pleura and peritoneum, was examined within two large cohorts of workers monitored for exposure to ionizing radiation. Methods and materials: Mortality was assessed among 253,632 workers routinely monitored for external radiation, including 30,724 industrial radiographers (IR) at shipyards, 142,583 workers at nuclear power plants (NPP), and 83,441 IR who had not worked at an NPP or shipyard. Follow-up was from 1969 through 2011. Standardized mortality ratios (SMRs) and 95% confidence intervals (CIs) were computed; observed numbers of deaths from mesothelioma (including cancers of the pleura and peritoneum) and asbestosis were compared with numbers expected based on age-, sex-, and calendar year-specific national mortality rates. Job history and quantitative asbestos exposure data were unavailable, but work at a shipyard was taken as a surrogate for the likelihood of exposure. Cox proportional hazards models were used to estimate hazard ratios (HRs) for mesothelioma in relation to estimated cumulative radiation exposure to the lung. Results: The mean duration of follow-up was 25.3 years (max 42 years). The mean cumulative lung dose was 28.6 mGy (7.3% > 250 mGy). Nearly 20% of the workers had died by 2011. A total of 421 mesothelioma deaths were found (75% occurring after 1999) with increased SMRs among workers monitored in shipyards (SMR 9.97; 95% CI 8.50-11.63) and for NPP workers (SMR 5.55; 95% CI 4.88-6.29), but not for IR who had not worked in shipyards (SMR 1.15; 95% CI 0.53-2.19). Likewise, deaths from asbestosis (n = 189) were also increased for shipyard and NPP workers (SMR = 18.1 and 9.2, respectively), but not among workers who never worked at a shipyard or NPP (SMR = 0.70; n = 1). Radiation dose to the lung was not associated with a statistically meaningful dose-response trend for mesothelioma in the combined cohorts (HR at 100 mGy = 1.10; 95% CI 0.96-1.27; p = .18), nor was mesothelioma risk associated with radiation exposure among IR who had not worked in a shipyard and assumed minimally exposed to asbestos. Conclusions: An elevated rate of death from mesothelioma was observed in two radiation-exposed occupational groups with potential for asbestos exposure. The increased risk of death from asbestosis, combined with little evidence of a rising trend in mesothelioma mortality with increasing radiation exposure, suggests that the mesothelioma (and asbestosis) excess in these workers was due to asbestos exposure in shipyards and power plants and not to occupational low-dose radiation.

Mesothelium and Malignant Mesothelioma

The mesothelium is an epithelial structure derived from the embryonic mesoderm. It plays an important role in the development of a number of different organs, including the heart, lungs, and intestines. In this publication, we discuss aspects of the development of the mesothelium, where mesothelial structures can be found, and review molecular and cellular characteristics associated with the mesothelium. Furthermore, we discuss the involvement of the mesothelium in a number of disease conditions, in particular in the pathogenesis of mesotheliomas with an emphasis on malignant pleural mesothelioma (MPM)—a primary cancer developing in the pleural cavity.

New Perspectives on Diagnosis and Therapy of Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but severe form of cancer, with an incidence that varies significantly within and among different countries around the world. It develops in about one to two persons per million of the general population, leading to thousands of deaths every year worldwide. To date, the MPM is mostly associated with occupational asbestos exposure. Asbestos represents the predominant etiological factor, with approximately 70% of cases of MPM with well-documented occupational exposure to asbestos, with the exposure time, on average greater than 40 years. Environmental exposure to asbestos is increasingly becoming recognized as a cause of mesothelioma, together with gene mutations. The possible roles of other cofactors, such as viral infection and radiation exposure, are still debated. MPM is a fatal tumor. This cancer arises during its early phase without clinical signs. Consequently, its diagnosis occurs at advanced stages. Standard clinical therapeutic approaches include surgery, chemo- and radiotherapies. Preclinical and clinical researches are making great strides in the field of this deadly disease, identifying new biomarkers and innovative therapeutic approaches. Among the newly identified markers and potential therapeutic targets, circulating microRNAs and the Notch pathway represent promising avenues that could result in the early detection of the tumor and novel therapeutic approaches.

Malignant Mesothelioma in Individuals With Nonmesothelial Neoplasms

CONTEXT

- Malignant mesothelioma (MM) is a component of the BAP1 tumor predisposition syndrome. Other than in BAP1 familial studies, nonmesothelial neoplasms in individuals with MM has not been comprehensively assessed.

OBJECTIVE

- To assess the spectrum and prevalence of nonmesothelial neoplasms in individuals with MM.

DESIGN

- Individuals with MM and second neoplasms were identified from a database of 3900 MM cases. The expected prevalence of each type of neoplasm was calculated and compared with the actual prevalence in the study population using available Surveillance, Epidemiology, and End Results data and other published data.

RESULTS

- Two hundred seventy nonmesothelial neoplasms were identified in 241 individuals (6% of the study population) with MM. Prostate adenocarcinoma was most common. Non-Hodgkin lymphoma, Hodgkin lymphoma, lung carcinoma, urothelial carcinoma, breast carcinoma, chronic lymphocytic leukemia, clear cell renal cell carcinoma, head and neck squamous cell carcinoma, papillary renal cell carcinoma, multiple myeloma/plasmacytoma, meningioma, pleomorphic undifferentiated sarcoma, chronic myelogenous leukemia, ocular melanoma, hepatocellular carcinoma, liposarcoma, and Wilms tumor all were more prevalent than expected.

CONCLUSIONS

- Nonmesothelial neoplasms are uncommon in individuals with MM, but certain tumor types are increased in prevalence. In an unselected study population with respect to BAP1 status, the prevalence of several tumor types described in BAP1 mutation carriers, including lung carcinoma, clear cell renal cell carcinoma, breast carcinoma, meningioma, pleomorphic undifferentiated sarcoma, and ocular melanoma, was increased.

Asbestos and SV40 in Malignant Pleural Mesothelioma from a Hyperendemic Area of North-Eastern Italy

Aims and background

Malignant mesothelioma is a fatal cancer of increasing incidence in north-eastern Italy. Together with asbestos, the polyomavirus SV40 was hypothesized to contribute to the onset of malignant mesothelioma. To investigate the putative role of SV40 in the individual susceptibility to asbestos-induced malignant mesothelioma, we conducted a molecular epidemiological study on a series of malignant mesothelioma patients from an area in north-eastern Italy hyperendemic for malignant pleural mesothelioma.

Methods and study design

We collected 63 mesothelioma samples from incidence cases of patients diagnosed with malignant pleural mesothelioma in the period 2009–2010. DNA was extracted from patients’ tissue biopsies using the BioRobot EZ1 Qiagen workstation. SV40 sequence detection and quantification was performed by specific real time PCR. The 74.6% of the 63 enrolled patients had a history of asbestos exposure. The epithelioid histotype was more prevalent in males (64.0%) and the mixed in females (61.5%) who showed significantly higher cancer co-morbidity (46.1% vs 12%, P = 0.005). SV40 was detected in 22% of MM tumors, with a low viral load. In SV40-positive patients, a threefold increased risk of asbestos exposure was observed, more evident in females (OR 4.32) than in males (OR 1.20).

Conclusions

Our findings indicate that a high prevalence of SV40 was present in malignant mesothelioma incident cases from an area hyperendemic for malignant mesothelioma in north-eastern Italy. Although asbestos is considered the main risk factor in malignant mesothelioma onset, a role for SV40 could be hypothesized.

Malignant Mesothelioma of the Pleura in Nonagenarian Patients

Aims and background

Malignant mesothelioma developing at very old ages is a rare event. The reasons for such late development were investigated.

Methods

A series of 811 malignant mesothelioma of the pleura, diagnosed at the Trieste and Monfalcone Hospitals, in northeastern Italy, in the period 1968–2008 were reviewed. Eight cases regarding patients aged 90 years or more were selected. In such cases, occupational histories were re-examined, and additional data could be obtained from the patients' relatives. Routine lung sections obtained at necropsy were examined for asbestos bodies. In 2 cases, asbestos bodies had been isolated after chemical digestion of lung tissue.

Results

The group included 7 men and one woman, aged between 90 and 93 years. All 8 patients had long-term histories of occupational exposure to asbestos, mostly in shipyards. Latency periods, elapsed between first exposure to asbestos and tumor manifestation, ranged between 64 and 75 years. Asbestos bodies were found on routine lung sections in 6 cases. Isolation of lung asbestos bodies showed 72, 000 bodies per gram of dried tissue in a90-year-old man, who had worked in the shipyards for 34 years, and 150 bodies per gram in a 93-year-old woman, who had worked in the shipyards for 23 years.

Conclusions

In this group of cases, the late development of mesothelioma can not be attributed to mild exposure to asbestos or to unusually late exposures. Very long latency periods even in people heavily exposed suggest an individual resistance to the oncogenic effects of asbestos.

Amatuximab and novel agents targeting mesothelin for solid tumors

Mesothelin (MSLN) is considered a promising target for cancer therapy. Originally extracted in 1992 after the immunization of mice with a human ovarian cancer (OC) cell line and cloned in 1996, MSLN seems to be involved in cell adhesion and metastasis. MSLN is prevalent in mesothelia tissues but is expressed in several human cancers, such as OC, pancreatic cancer, mesothelioma, and lung cancer. Amatuximab (MORAb-009) is a mouse-human chimeric monoclonal antibody with a selective affinity for MSLN. The principal mechanism of action comprises inhibition of binding of MSLN with the antigen CA125/MUC16. The highest phase of development is actually a Phase II trial (MORAb-009-201, Europe). In this review, we describe the mechanism of action of amatuximab and other MSLN-targeting novel drugs, along with a discussion about the expected efficacy, safety, and toxicity of this promising group of agents and implications for future research and clinical practice.

Radiation exposure and lung disease in today's nuclear world

PURPOSE OF REVIEW

Ionizing radiation poses important health risks. The per capita annual dose rate has increased in the United States and there is increasing concern for the risks posed by low-dose occupational exposure among workers in nuclear industries and healthcare. Recent nuclear accidents and concern for terrorism have heightened concern for catastrophic, high-dose ionizing radiation exposure. This review will highlight recent research into the risks to lung health posed by ionizing radiation exposure and into potential treatments.

RECENT FINDINGS

Angiotensin-converting enzyme inhibitors and some antioxidants have shown promise as mitigators, to decrease pneumonitis and fibrosis when given after exposure. Studies of survivors of nuclear catastrophes have shown increased risk for lung cancer, especially in nonsmokers. There is evidence for increased lung cancer risk in industrial radiation workers, especially those who process plutonium and may inhale radioactive particles. There does not seem to be an increased risk of lung cancer in healthcare workers who perform fluoroscopic procedures.

SUMMARY

High-dose ionizing radiation exposure causes pneumonitis and fibrosis, and more research is needed to develop mitigators to improve outcomes in nuclear catastrophes. Long-term, low-dose occupational radiation may increase lung cancer risk. More research to better define this risk could lead to improved safety protocols and screening programs.

Targeting microRNA to improve diagnostic and therapeutic approaches for malignant mesothelioma

Malignant mesothelioma is an aggressive and often fatal cancer associated with asbestos exposure. The disease originates in the mesothelial lining of the serosal cavities, most commonly affecting the pleura. Survival rates are low as diagnosis often occurs at an advanced stage and current treatments are limited. Identifying new diagnostic and therapeutic targets for mesothelioma remains a priority, particularly for the new wave of victims exposed to asbestos through do-it-yourself renovations and in countries where asbestos is still mined and used. Recent advances have demonstrated a biological role for the small but powerful gene regulators microRNA (miRNA) in mesothelioma. A number of potential therapeutic targets have been identified. MiRNA have also become popular as potential biomarkers for mesothelioma due to their stable expression in bodily fluid and tissues. In this review, we highlight the current challenges associated with the diagnosis and treatment of mesothelioma and discuss how targeting miRNA may improve diagnostic, prognostic and therapeutic approaches.

Immunotherapy advances for mesothelioma treatment

INTRODUCTION

Mesothelioma is a rare type of cancer that is strongly tied to asbestos exposure. Despite application of different modalities such as chemotherapy, radiotherapy and surgery, patient prognosis remains very poor and therapies are ineffective. Much research currently focuses on the application of novel approaches such as immunotherapy towards this disease. Areas covered: The types, stages and aetiology of mesothelioma are detailed, followed by a discussion of the current treatment options such as radiotherapy, surgery, and chemotherapy. A description of innate and adaptive immunity and the principles and justification of immunotherapy is also included. Clinical trials for different immunotherapeutic modalities are described, and lastly the article closes with an expert commentary and five-year view, the former of which is summarised below. Expert commentary: Current efforts for novel mesothelioma therapies have been limited by attempting to apply treatments from other cancers, an approach which is not based on a solid understanding of mesothelioma biology. In our view, the influence of the hostile, hypoxic microenvironment and the gene expression and metabolic changes that resultantly occur should be characterised to improve therapies. Lastly, clinical trials should focus on overall survival rather than surrogate endpoints to avoid bias and inaccurate reflections of treatment effects.

Novel systemic therapy against malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive tumor of the pleura with an overall poor prognosis. Even with surgical resection, for which only a subset of patients are eligible, long term disease free survival is rare. Standard first-line systemic treatment consists of a platinum analog, an anti-metabolite, and sometimes anti-angiogenic therapy, but there is currently no well-established standard therapy for refractory or relapsed disease. This review focuses on efforts to develop improved systemic therapy for the treatment of malignant pleural mesothelioma (MPM) including cytotoxic systemic therapy, a variety of tyrosine kinase inhibitors and their downstream effector pathways, pharmacologic targeting of the epigenome, novel approaches to target proteins expressed on mesothelioma cells (such as mesothelin), arginine depletion therapy, and the emerging role of immunotherapy. Overall, these studies demonstrate the challenges of improving systemic therapy for MPM and highlight the need to develop therapeutic strategies to control this disease.

Switching off malignant mesothelioma: exploiting the hypoxic microenvironment

Malignant mesotheliomas are aggressive, asbestos-related cancers with poor patient prognosis, typically arising in the mesothelial surfaces of tissues in pleural and peritoneal cavity. The relative unspecific symptoms of mesotheliomas, misdiagnoses, and lack of precise targeted therapies call for a more critical assessment of this disease. In the present review, we categorize commonly identified genomic aberrations of mesotheliomas into their canonical pathways and discuss targeting these pathways in the context of tumor hypoxia, a hallmark of cancer known to render solid tumors more resistant to radiation and most chemo-therapy. We then explore the concept that the intrinsic hypoxic microenvironment of mesotheliomas can be Achilles' heel for targeted, multimodal therapeutic intervention.

Diffuse malignant mesothelioma and synchronous lung cancer: A clinicopathological study of 18 cases

OBJECTIVES

To examine the clinicopathologic characteristics of individuals with diffuse malignant mesothelioma (DMM) occurring concurrently with lung cancer (LC).

MATERIALS AND METHODS

A database of approximately 3800 patients with DMM was reviewed, from which 18 patients (0.5%) who had synchronous LC were identified. The clinicopathologic features, as well as the occupational exposure history and fiber burden analysis data were examined.

RESULTS

The patient median age was 68 years (range 58-84 years). Of the 18 patients (14 male, 4 female), 11 (61%) had epithelial, 5 (28%) had biphasic, and 2 (11%) had sarcomatoid DMM, with the majority (16 cases; 89%) originating in the pleura and only 2 were peritoneal. Among the histologic types of LC, adenocarcinoma was most frequent (12 cases; 67%), while 5 cases of squamous cell carcinoma, and 1 case of small cell carcinoma were observed. Three patients also had a history of prior malignancy (1 with testicular seminoma and bladder carcinoma and 2 with prostate carcinoma). Fifteen patients had a positive smoking history. All but 3 had documented asbestos exposure. Three had histologic features of asbestosis. Mineral analysis performed in 8 showed an elevated asbestos fiber burden in 4 (22%). Amosite was detected in 4 patients, crocidolite in 3, and non-commercial amphiboles in 5.

CONCLUSION

The finding of simultaneous carcinoma of the lung and DMM is distinctly unusual. The majority of patients are male smokers with pleural epithelial DMM and lung adenocarcinoma. This study represents the largest cohort of patients reported to date with synchronous malignant mesothelioma and lung cancer, and we propose guidelines for making a diagnosis of synchronous malignant mesothelioma and primary lung cancer.

Radiation-induced mesothelioma among long-term solid cancer survivors: a longitudinal analysis of SEER database

We investigated the association between external beam radiotherapy (EBRT) and pleural and peritoneal mesothelioma among long‐term (>5 years) solid cancer survivors. We analyzed data from the US Surveillance, Epidemiology, and End Results (SEER) program (1973–2012). We fitted survival models adjusted by age, gender, race, year, surgery, and relative risk of primary mesothelioma in the county of residence (proxy for individual asbestos exposure). We estimated hazard ratios [HR] with reference to nonirradiated patients. We distinguished between scattered and direct irradiation to study the dose–response. We observed 301 mesotheliomas (265 pleural; 32 peritoneal; 4 others) among 935,637 patients. EBRT increased the risk of mesothelioma (any site; HR 1.34, 95% CI 1.04–1.77). We observed an increased risk of pleural mesothelioma (HR for EBRT 1.34, 95% CI 1.01–1.77), but we did not find signs of a dose–response relationship (HR for scattered irradiation 1.38; HR for direct irradiation 1.23). On the opposite, only direct peritoneal irradiation was associated with peritoneal mesothelioma (HR 2.20, 95% CI 0.99–4.88), particularly for latencies ≥10 years (HR 3.28, 95% CI 1.14–9.43). A competing risks analysis revealed that the clinical impact of radiation‐induced mesothelioma was limited by the high frequency of competing events. The cumulative incidence function of mesothelioma after 40 years of observation was very low (nonirradiated patients 0.00032, irradiated patients 0.00055).EBRT might be a determinant of mesothelioma. Longer latency periods are associated with higher risks, while the dose–response seems nonlinear. The clinical impact of mesothelioma after EBRT for primary solid cancers is limited.

Peritoneal mesothelioma in Italy: Trends and geography of mortality and incidence

INTRODUCTION

Peritoneal mesothelioma, a very rare and lethal malignancy, has not been investigated as extensively as pleural mesothelioma, although the role of asbestos exposure in its occurrence is well-known. Data from Italy are relevant, as it was the largest European asbestos producer, and asbestos was widely used in many economic activities.

METHODS

A population-based mortality and incidence analysis was performed in Italy. Data sources were the National Multiple-causes-of-death Database (1995-2010) and the Italian Mesothelioma Register (1993-2008).

RESULTS

We found an increasing trend of age standardized mortality rates in men, but no clear trend in women; moreover, we showed significant risks of death in several northern regions, formerly heavy asbestos users; finally, mortality/incidence ratios similar for both genders (about 0.8) were estimated.

CONCLUSIONS

The study, based on national data, showed a higher risk of mortality from and incidence of peritoneal mesothelioma in areas with formerly heavy exposure to asbestos.

Malignant mesothelioma and central nervous system metastases. Report of two cases, pooled analysis, and systematic review

RATIONALE

The incidence and patterns of metastatic disease to the central nervous system (CNS) from malignant mesothelioma are not well characterized.

OBJECTIVES

We describe the treatment of two cases of pleural mesothelioma with CNS metastases. We also report the results of a systematic review with pooled data analysis of CNS metastases from malignant mesothelioma.

METHODS

PubMed, Scopus, EMBASE, and Web of Science were searched to identify relevant published studies. Inclusion criteria for the pooled analysis were any clinical or autopsy study in which patients had a confirmed histological diagnosis of malignant mesothelioma and CNS metastasis was identified by autopsy, clinical pathological specimen, or compelling radiographic imaging. Case reports were excluded from the pooled analysis but were incorporated into the discussion. One hundred forty-one potentially relevant references were identified. Seven studies including 655 patients were included in the pooled analysis. Ninety-seven additional cases were identified and incorporated into the discussion. A systematic review of the literature is provided with pooled data analysis.

MEASUREMENTS AND MAIN RESULTS

CNS involvement of malignant mesothelioma may occur by hematogenous spread or by local extension. Some cases may represent tumor dedifferentiation to a more aggressive histologic subtype. Surgery or stereotactic therapies may play a role for select patients; however, rapid recurrence has been reported.

CONCLUSIONS

The prognostic significance of CNS disease is not well characterized. Clinicians should consider and identify CNS involvement in patients with new or evolving neurologic symptoms because early identification may allow for palliative intervention.

Malignant pleural mesothelioma: history, controversy and future of a manmade epidemic

Asbestos is the term for a family of naturally occurring minerals that have been used on a small scale since ancient times. Industrialisation demanded increased mining and refining in the 20th century, and in 1960, Wagner, Sleggs and Marchand from South Africa linked asbestos to mesothelioma, paving the way to the current knowledge of the aetiology, epidemiology and biology of malignant pleural mesothelioma. Pleural mesothelioma is one of the most lethal cancers, with increasing incidence worldwide. This review will give some snapshots of the history of pleural mesothelioma discovery, and the body of epidemiological and biological research, including some of the controversies and unresolved questions. Translational research is currently unravelling novel circulating biomarkers for earlier diagnosis and novel treatment targets. Current breakthrough discoveries of clinically promising noninvasive biomarkers, such as the 13-protein signature, microRNAs and the BAP1 mesothelioma/cancer syndrome, are highlighted. The asbestos history is a lesson to not be repeated, but here we also review recent in vivo and in vitro studies showing that manmade carbon nanofibres could pose a similar danger to human health. This should be taken seriously by regulatory bodies to ensure thorough testing of novel materials before release in the society.

Malignant pleural mesothelioma is a cancer with increasing death tolls due to the past and present use of asbestoshttp://ow.ly/DhA2y

Clinicopathologic Characteristics of Malignant Mesotheliomas Arising in Patients With a History of Radiation for Hodgkin and Non-Hodgkin Lymphoma

Purpose

Studies have reported an association between pleural diffuse malignant mesothelioma (PDMM) and chest radiation for lymphoma. The clinicopathologic characteristics of malignant mesotheliomas arising in these patients have not been established.

Patients and Methods

We studied 1,618 consecutive patients diagnosed with pleural PDMM from July 1993 to February 2008 and identified patients with a history of radiation for Hodgkin and non-Hodgkin lymphoma. We evaluated the histology in the surgical resection specimens and compared clinicopathologic features with overall survival.

Results

We identified 22 patients who developed PDMM after chest radiation as part of their treatment for lymphoma (mean latency time, 21.4 years; 95% CI, 17.0 to 25.8 years). Asbestos bodies in lymphoma-associated PDMM were lower than in asbestos-associated PDMM (median count, 15 v 325 bodies, respectively; P < .001) and similar to an unexposed control group (median count, 15 v 10 bodies, respectively; P = .6). Seventeen lymphoma-associated PDMMs (77%) were epithelioid and five (23%) were biphasic. Seven PDMMs (32%) had unusual histologies (pleomorphic, myxoid, clear cell, and signet ring cell). Patients with lymphoma-associated PDMM were younger than patients with asbestos-associated PDMM (median age, 45 v 64 years, respectively; P < .001) and had a significantly longer overall survival time (median, 32.5 v 12.7 months, respectively; P = .018). In multivariate analysis, independent favorable predictors for overall survival were history of prior radiation (P = .022), female sex (P < .001), age ≤ 65 years (P = .005), cytoreductive surgery (P < .001), and epithelioid histology (P < .001).

Conclusion

Patients with lymphoma-associated PDMM are likely to have unusual histologic features, are significantly younger, and seem to have a longer overall survival compared with patients with asbestos-associated PDMM.

Medicolegal Aspects of Asbestos I — Malignant Mesothelioma and Lung Cancer

Inhalation of asbestos fibers can cause a variety of conditions, benign and malignant, of the lungs and pleura. Illnesses and deaths in which asbestos may have had a causal or contributory role are often the subject of litigation. Forensic pathologists (FP) can become involved in some of these cases in their capacity of a medical examiner or coroner, autopsy pathologist or as an expert retained by one or more parties involved in litigation. FP input may be sought to address issues such as diagnosis, assessment of exposure, and attribution. This review will discuss medicolegal issues that surround lung and mesothelial tumors that can be caused by the inhalation of asbestos fibers.

Characterization of a French series of female cases of mesothelioma

BACKGROUND

More than 80% of mesothelioma cases in men are attributable to occupational asbestos exposure compared to only 40% in women. The objective of the study was to characterize a series of female pleural mesotheliomas according to known and suspected risk factors.

METHODS

From the exhaustive recording of 318 female mesothelioma cases in the French National Mesothelioma Surveillance Program between 1998 and 2009, multiple correspondence analysis and hybrid clustering were performed to characterize these cases according to expert assessed occupational and non-occupational exposure to asbestos and man-made vitreous fibers, X-ray exposure, and history of cancer and non-malignant respiratory diseases.

RESULTS

Four clusters were identified: (1) occupational exposure to asbestos and man-made vitreous fibers (7.9% of subjects); (2) radiation exposure during radiotherapy (12.9%); (3) increased asbestos exposure (19.8%); and (4) "non-exposure" characteristics (59.4%).

CONCLUSION

These results will allow hypotheses to be generated about associations between mesothelioma and non-occupational asbestos exposure, X-ray exposure and history of respiratory disease.

[Malignant pleural mesothelioma after radiation treatment for Hodgkin lymphoma]

Malignant mesothelioma is a relatively uncommon malignancy. Although the pathogenesis is primarily related to asbestos, the role of ionizing radiation is more controversial. We report the case of a 41-year-old male who developed pleural mesothelioma. He had both, a prior short asbestos exposure and a thoracic radiotherapy for Hodgkin's disease 26years before. The evidence for radiotherapy as cause for mesothelioma is expanding and the diagnosis of mesothelioma in patients who had previous irradiation should be kept in mind.

Risk of mesothelioma following external beam radiotherapy for prostate cancer: a cohort analysis of SEER database

Purpose

To investigate the association between external beam radiotherapy (EBRT) for prostate cancer and mesothelioma using data from the US Surveillance, Epidemiology, and End Results (SEER) cancer registries.

Methods

We analyzed data from the SEER database (1973–2009). We compared EBRT versus no radiotherapy. Incidence rate ratios (IRR) and 95 % confidence intervals (95 % CI) of mesothelioma among prostate cancer patients were estimated with multilevel Poisson models adjusted by race, age, and calendar year. Confounding by asbestos was investigated using relative risk of mesothelioma in each case’s county of residence as a proxy for asbestos exposure.

Results

Four hundred and seventy-one mesothelioma cases (93.6 % pleural) occurred in 3,985,991 person-years. The IRR of mesothelioma was increased for subjects exposed to EBRT (1.28; 95 % CI 1.05, 1.55) compared to non-irradiated patients, and a population attributable fraction of 0.49 % (95 % CI 0.11, 0.81) was estimated. The IRR increased with latency period: 0–4 years, IRR 1.08 (95 % CI 0.81, 1.44); 5–9 years, IRR 1.31 (95 % CI 0.93, 1.85); ≥10 years, IRR 1.59 (95 % CI 1.05, 2.42). Despite the fairly strong evidence of association with EBRT, the population attributable rate of mesothelioma was modest—3.3 cases per 100,000 person-years. The cumulative incidence of mesothelioma attributable to EBRT was 4.0/100,000 over 5 years, 24.5/100,000 over 10 years, and 65.0/100,000 over 15 years.

Conclusions

Our study provides evidence that EBRT for prostate cancer is a small but detectable risk factor for mesothelioma. Patients should be advised of risk of radiation-induced second malignancies.

Electronic supplementary material

The online version of this article (doi:10.1007/s10552-013-0230-0) contains supplementary material, which is available to authorized users.

Analyses of radiation and mesothelioma in the US Transuranium and Uranium Registries

OBJECTIVES

We examined the relationship between radiation and excess deaths from mesothelioma among deceased nuclear workers who were part of the US Transuranium and Uranium Registries.

METHODS

We performed univariate analysis with SAS Version 9.1 software. We conducted proportionate mortality ratio (PMR) and proportionate cancer mortality ratio (PCMR) analyses using the National Institute for Occupational Safety and Health Life Table Analysis System with the referent group being all deaths in the United States.

RESULTS

We found a PMR of 62.40 (P < .05) and a PCMR of 46.92 (P < .05) for mesothelioma. PMRs for the 4 cumulative external radiation dose quartiles were 61.83, 57.43, 74.46, and 83.31. PCMRs were 36.16, 47.07, 51.35, and 67.73. The PMR and PCMR for trachea, bronchus, and lung cancer were not significantly elevated.

CONCLUSIONS

The relationship between cumulative external radiation dose and the PMR and PCMR for mesothelioma suggests that external radiation at nuclear facilities is associated with an increased risk of mesothelioma. The lack of a significantly elevated PMR and PCMR for trachea, bronchus, and lung cancer suggests that asbestos did not confound this relationship.