Therapeutic radiation for lymphoma: risk of malignant mesothelioma

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 Updated Contextual Approach to Mesothelial Proliferations in Pleural Effusion Cytology Leveraging Morphology, Ancillary Studies, and Novel Biomarkers

CONTEXT.—

Pleural effusions are common cytologic specimens that can be leveraged to make diagnoses of malignancy that drive appropriate patient management. However, the overlap in morphologic features of reactive mesothelial proliferations, mesotheliomas, and adenocarcinomas can create diagnostic pitfalls in the cytologic evaluation of pleural fluids.

OBJECTIVE.—

To review the morphologic spectrum of benign and malignant mesothelial proliferations in pleural effusions, as well as relevant clinicoradiologic contexts and ancillary tests.

DATA SOURCES.—

Existing scientific and clinical literature as of January 2023.

CONCLUSIONS.—

We can leverage the knowledge of several overlapping morphologic features, clinicoradiologic scenarios, and immunohistochemical studies to enhance the diagnostic accuracy of pleural effusion cytology to appropriately delineate cases of adenocarcinoma, reactive mesothelial proliferation, and mesothelioma. Earlier diagnosis through cytology, particularly in cases of mesothelioma, may positively impact patient treatment options and prognosis.

Comprehensive bioinformatics analysis of the role of VWF in the tumor microenvironment of malignant mesothelioma

To explore the influence and effect of tumor microenvironment on the development of malignant mesothelioma using machine learning methods. 87 open cases were downloaded from the Cancer Genome Atlas database including transcriptome data, clinical data, and mutation data. The immune, stromal, and estimate scores were calculated for each case by using the ESTIMATE algorithm, and then the cases were grouped according to high and low stromal scores to predict all-cause survival in malignant mesothelioma cases. Their mutation data were analyzed to reveal the differences in mutated genes between the 2 groups, and then the von Willebrand factor (VWF) and FCRL3 genes were identified according to the intersection of DEGs and high-frequency mutated genes. Lastly, the correlation between VWF and the immune checkpoint of 22 kinds of immune cells was analyzed by using the CIBERSORT package of R software. A significant difference was found in the survival time of patients between the high and low stromal score groups. High expression of the VWF gene was negatively correlated with the prognosis of malignant mesothelioma, and the expression of VWF was positively correlated with naive B cells and activated CD4 memory T cells and negatively correlated with NK cells. The results revealed that high expression of VWF may involve in the development of malignant mesothelioma, and the anti-CTLA4 immune checkpoint treatment may have certain efficacy.

Chinese expert consensus on the diagnosis and treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a malignant tumor originating from the pleura, and its incidence has been increasing in recent years. Due to the insidious onset and strong local invasiveness of MPM, most patients are diagnosed in the late stage and early screening and treatment for high-risk populations are crucial. The treatment of MPM mainly includes surgery, chemotherapy, and radiotherapy. Immunotherapy and electric field therapy have also been applied, leading to further improvements in patient survival. The Mesothelioma Group of the Yangtze River Delta Lung Cancer Cooperation Group (East China LUng caNcer Group, ECLUNG; Youth Committee) developed a national consensus on the clinical diagnosis and treatment of MPM based on existing clinical research evidence and the opinions of national experts. This consensus aims to promote the homogenization and standardization of MPM diagnosis and treatment in China, covering epidemiology, diagnosis, treatment, and follow-up.

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.

Genomics of Tumor Origin and Characteristics for Adenocarcinoma and Malignant Pleural Mesothelioma: A Case Report

A female underwent a right middle lobectomy for a pulmonary adenocarcinoma (AD). She eventually died of a right malignant pleural mesothelioma (MPM; sarcomatoid type) 4 years and 7 months after the removal of the AD even though she did not have any history of asbestos exposure, smoking, or radiation exposure. Her chest CT revealed multiple pulmonary nodules and bilateral pleural effusion with a right pleural tumor directly invading into the abdominal cavity. The genomics of tumor origin and characteristics were examined for the AD and the MPM. As a result, 50 somatic variants were detected in the AD, and 29 somatic variants were detected in the MPM. The variants which were common in both the AD and the MPM were not present, which suggested that the AD and the MPM had occurred independently in different origins. The MPM had two driver oncogenes of TP53 and EP300, but the AD did not. Two driver oncogenes of TP53 and EP300 were hypothesized to make the MPM aggressive. The speed at which the MPM progressed without the patient having a history of asbestos exposure, smoking, or radiation exposure was alarming.

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.

Epidemiology and Clinical Aspects of Malignant Pleural Mesothelioma

Mesothelioma is a cancer predominantly of the pleural cavity. There is a clear association of exposure to asbestos with a dose dependent risk of mesothelioma. The incidence of mesothelioma in different countries reflect the historical patterns of commercial asbestos utilisation in the last century and predominant occupational exposures mean that mesothelioma is mostly seen in males. Modern imaging techniques and advances in immunohistochemical staining have contributed to an improved diagnosis of mesothelioma. There have also been recent advances in immune checkpoint inhibition, however, mesothelioma remains very challenging to manage, especially considering its limited response to conventional systemic anticancer therapy and that no cure exists. Palliative interventions and support remain paramount with a median survival of 9-12 months after diagnosis. The epidemiology and diagnosis of mesothelioma has been debated over previous decades, due to a number of factors, such as the long latent period following asbestos exposure and disease occurrence, the different potencies of the various forms of asbestos used commercially, the occurrence of mesothelioma in the peritoneal cavity and its heterogeneous pathological and cytological appearances. This review will describe the contemporary knowledge on the epidemiology of mesothelioma and provide an overview of the best clinical practice including diagnostic approaches and management.

Malignant Pleural Mesothelioma Epidemiology in the United States From 2000 to 2016

Introduction

Pleural mesothelioma constitutes about 80% of all mesotheliomas. The peak incidence of malignant mesothelioma estimated using the cancer registries was in early 1990 to 2000 in the United States. The disease is primarily associated with asbestos exposure. The latency period between asbestos exposure and the development of malignant pleural mesothelioma (MPM) can range anywhere from 15 to 60 years. Asbestos exposure was peaked during the industrial revolution and World War II due to military and shipyard exposures. It is often difficult for the pathologist to distinguish different histological subtypes; due to the disease's rarity and the inadequate tissue sample obtained. There is no available data on the difference in epidemiology of different subtypes of MPM. Surveillance Epidemiology and End Results (SEER), cancer incidence data include population-based registries covering approximately 34.6% of the U.S. population. Here in our study, we analyze malignant pleural mesothelioma epidemiology in the United States, emphasizing different histological subtypes.

Methods

SEER data from 2000 to 2016 was used in our study. The primary site of cancer is selected as pleura, and malignant behavior only is selected as the filter. Data were analyzed using the SEER stat program. Overall epidemiology of MPM and epidemiology of epithelioid, fibrous, and biphasic histological subtypes were analyzed separately. We used annual percentage change (APC) to evaluate the trend in the epidemiology of MPM.

Results summary

A total of 11,857 cases of MPM were included in the primary cohort from the SEER 18 registry from 2000 to 2016. The total prevalence of MPM was highest in 2009 and was lowest in 2016. The APC in MPM incidence during this period is -2.0. After removing 5,989 cases with non-specified histology during the same period, the APC for each histological type is -0.7 for fibrous type, 1.8 for epithelioid type, and 2.9 for biphasic type. Out of 17 regional registries included in the study, the greatest statistically significant change in APC was seen in the Hawaiian registry -4.1. In contrast, the lowest statistically significant difference was seen in Seattle (Puget Sound) registry -1.7. The APC in the incidence of MPM among males during the study period was -2.4 while that of females was -0.9. The Iowa registry showed a statistically significant increase in APC of the epithelioid malignant mesothelioma with a statistically insignificant reduction in the overall MPM APC.

Conclusion

The overall incidence of MPM in the United States is declining, while the data showed an increase in the incidence of epithelioid and biphasic histological subtypes. The authors believe that these conflicting results can be attributed to improved histological diagnosis and improved biopsy techniques.

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.

Update on biology and management of mesothelioma

Malignant pleural mesothelioma is an aggressive, incurable cancer that is usually caused by asbestos exposure several decades before symptoms arise. Despite widespread prohibition of asbestos production and supply, its incidence continues to increase. It is heterogeneous in its presentation and behaviour, and diagnosis can be notoriously difficult. Identification of actionable gene mutations has proven challenging and current treatment options are largely ineffective, with a median survival of 10-12 months.However, the past few years have witnessed major advances in our understanding of the biology and pathogenesis of mesothelioma. This has also revealed the limitations of existing diagnostic algorithms and identified new treatment targets.Recent clinical trials have re-examined the role of surgery, provided new options for the management of associated pleural effusions and heralded the addition of targeted therapies. The increasing complexity of mesothelioma management, along with a desperate need for further research, means that a multidisciplinary team framework is essential for the delivery of contemporary mesothelioma care.This review provides a synthesised overview of the current state of knowledge and an update on the latest research in the field.

A series of patients with unusual lung cancers with unusual presentations

Lung malignancies have become increasingly prevalent. Occasionally, an unusual tumour is diagnosed, or a common tumour type presents unusually. This case report reviews 3 cases of thoracic neoplasm, including two cases of uncommon cancers (primary lung adenoid cystic carcinoma and thoracic desmoplastic small round cell high-grade sarcoma) and an atypical presentation of malignant mesothelioma.

Clinicopathologic and genetic characteristics of young patients with pleural diffuse malignant mesothelioma

Pleural diffuse malignant mesothelioma typically presents during the seventh decade of life and has poor prognosis. Recent epidemiologic studies have shown differences between young and older mesothelioma patients, but the biology of pleural mesothelioma in young patients is poorly understood. We studied the clinicopathologic and genetic characteristics in pleural mesothelioma patients aged 35 years and younger. Thirty-six consecutive pleural mesothelioma patients aged 35 years and younger were compared with 48 older patients. We examined demographic and clinical characteristics, histologic type, growth patterns, mitotic index, and nuclear grade on hematoxylin and eosin-stained slides, BAP1 protein expression by immunohistochemistry, and CDKN2A and NF2 deletions by fluorescence in situ hybridization. Clinicopathologic and cytogenetic results were compared between young and older groups, and correlated with overall survival. Young patients were more frequently women, reported less asbestos exposure, and had a greater frequency of prior therapeutic radiation and family history of breast cancer than older patients (P<0.05 each). There were no histologic differences between young and older patients (all P>0.05). CDKN2A deletion was less prevalent in young patients (P=0.01), loss of BAP1 protein expression less frequent in young patients (P=0.06), and NF2 deletion rates similar between groups (P>0.05 each). Median overall survival was 40 vs 26 months (P=0.10) in young and older patients, respectively, and 47 vs 31 months (P=0.04) when comparing patients with epithelioid histology only. High mitotic index and non-epithelioid histology were the only characteristics associated with a poor overall survival in young patients. Young patients with pleural mesothelioma have an equal sex distribution and are more likely to have a history of mantle radiation, family history of breast cancer, and lower rates of CDKN2A deletion than older patients. Our results suggest that pleural mesothelioma in young patients has distinctive clinical and genetic characteristics, despite some similarities to pleural mesothelioma in older patients.

Therapeutic radiation for lymphoma and risk of second primary malignant mesothelioma

PURPOSE

This large, population-based U.S. study of lymphoma patients followed for up to four decades enables detailed analysis of second primary mesothelioma risk after radiotherapy.

METHODS

U.S. Surveillance, Epidemiology, and End Results data were used to identify second primary mesothelioma among patients diagnosed with Hodgkin lymphoma (HL) or non-Hodgkin lymphoma (NHL) between 1973 and 2014. Standardized incidence ratios (SIRs) were calculated by radiotherapy. Multivariate adjusted associations were examined using competing risks survival analysis.

RESULTS

Among 47,219 HL patients (19,538 irradiated) and 252,090 NHL patients (52,454 irradiated), second primary mesothelioma developed among 28 lymphoma patients who received radiotherapy and 59 who did not. Mesothelioma risk was increased among HL and NHL patients treated with radiotherapy [SIR = 1.78, 95% confidence interval (CI) 1.18-2.58], but not without radiotherapy. After multivariate adjustment, radiotherapy was associated with increased mesothelioma risk (relative risk = 1.64, 95% CI 1.05-2.57), especially in lymphoma patients diagnosed before 1995 and after a latency of at least 10 years, and apparently with younger age at diagnosis.

CONCLUSIONS

The increase in second primary mesothelioma risk following radiotherapy for lymphoma is independent of several patient and disease characteristics, and is higher with earlier treatment era and longer latency.

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.

Epidemiology of mesothelioma of the pericardium and tunica vaginalis testis

PURPOSE

Malignant mesothelioma most commonly arises in the pleura and peritoneum but also occurs rarely at other anatomical sites with mesothelial tissue, namely, the pericardium and tunica vaginalis testis (TVT). This review provides a better understanding of the epidemiology of mesothelioma of these extrapleural sites.

METHODS

We conducted a systematic review of the epidemiologic and clinical literature on pericardial mesothelioma and mesothelioma of the TVT. We also analyzed U.S. Surveillance, Epidemiology, and End Results cancer registry data to describe incidence patterns of these malignancies.

RESULTS

An etiologic role of asbestos exposure has been hypothesized for pericardial and TVT mesotheliomas, but no analytical case-control epidemiologic studies exist to test this relationship. A substantial proportion of cases with these malignancies report no known asbestos exposure. In large occupational cohorts with heavy asbestos exposures, no cases of pericardial or TVT mesothelioma have been reported. Trends in the incidence of these malignancies do not match those of pleural mesothelioma, which correspond to historical trends of commercial asbestos use. A male preponderance of pericardial mesothelioma is not evident.

CONCLUSIONS

In the absence of analytic epidemiologic studies, the etiologic role of environmental risk factors for mesothelioma of the pericardium and TVT remains elusive.

The evolution of the diminishing role of extrapleural pneumonectomy in the surgical management of malignant pleural mesothelioma

Malignant pleural mesothelioma is an uncommon and aggressive thoracic malignancy that is rarely curable, even when multimodality therapy is used. Systemic chemotherapy is the primary treatment for the majority of patients with this disease; however, surgical resection may benefit a subset of patients with early-stage disease. The surgical approach that offers the best outcomes remains an area of controversy, with data from retrospective comparisons being the only guide. Historically, extrapleural pneumonectomy (EPP) has been the standard procedure, carrying with it a cost of significant morbidity and impact on quality of life that has raised questions regarding its routine application. Over the past two decades as surgical techniques have been refined and survival data with EPP in large case series have been reported, the paradigm has evolved toward the use of lung-sparing pleural resections such as pleurectomy/decortication (P/D) and extended P/D. The identification of patients who may benefit from EPP over pleurectomy has proven problematic, and the larger question regarding the impact of any type of surgical intervention on outcomes for pleural mesothelioma patients is still an area of investigation. Uniform treatment approaches have been difficult to develop due to the relatively small numbers of patients with this disease, the use of a staging system that does not readily identify those who may benefit from more aggressive therapy, and the institutional biases that have resulted from the growth of multimodality centers of excellence.

Distinctive clinical characteristics of malignant mesothelioma in young patients

Although considered a disease of the elderly, a subset of patients with mesothelioma are young (<40 years). The goal of this study was to understand their characteristics and outcomes. The Surveillance, Epidemiology, and End Results (SEER) database was used to extract mesothelioma cases (1990-2010). We modeled Kaplan-Meyer survival curves stratified by site of disease, and age of presentation. 2% (207 of 12345) of mesothelioma patients are young. Sex distribution is comparable among the young (51% males, 49% females); males predominated (78%, 22%) in the older cohort. Frequency of pleural and peritoneal mesothelioma are similar in the young (47%, 48% respectively); pleural disease predominated in the old (90%, 9%). Cancer-directed surgeries are more frequent in the young. Regardless of histologic subtype, young patients with pleural (11 vs. 8 months) and peritoneal (not reached vs. 10 months) mesothelioma had significantly improved overall survival. In multivariate analysis, younger age was an independent prognostic factor. Although rare, mesothelioma do occur in the young; their characteristics are distinct from those of older patients. Further studies are needed to understand the interplay between genetic susceptibility and mineral fiber carcinogenesis in the pathogenesis of mesothelioma in the young.

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.

Genome-wide analysis of abdominal and pleural malignant mesothelioma with DNA arrays reveals both common and distinct regions of copy number alteration

Malignant mesothelioma (MM) is an aggressive tumor arising from mesothelial linings of the serosal cavities. Pleural space is the most common site, accounting for about 80% of cases, while peritoneum makes up the majority of the remaining 20%. While histologically similar, tumors from these sites are epidemiologically and clinically distinct and their attribution to asbestos exposure differs. We compared DNA array-based findings from 48 epithelioid peritoneal MMs and 41 epithelioid pleural MMs to identify similarities and differences in copy number alterations (CNAs). Losses in 3p (BAP1 gene), 9p (CDKN2A) and 22q (NF2) were seen in tumors from both tumor sites, although CDKN2A and NF2 losses were seen at a higher rate in pleural disease (p<0.01). Overall, regions of copy number gain were more common in peritoneal MM, whereas losses were more common in pleural MM, with regions of loss containing known tumor suppressor genes and regions of gain encompassing genes encoding receptor tyrosine kinase pathway members. Cases with known asbestos causation (n = 32 ) were compared with those linked to radiation exposure (n = 9 ). Deletions in 6q, 14q, 17p and 22q, and gain of 17q were seen in asbestos-associated but not radiation-related cases. As reported in post-radiation sarcoma, gains outnumbered losses in radiation-associated MM. The patterns of genomic imbalances suggest overlapping and distinct molecular pathways in MM of the pleura and peritoneum, and that differences in causation (i.e., asbestos vs. radiation) may account for some of these site-dependent differences.

Current issues in malignant pleural mesothelioma evaluation and management

Malignant pleural mesothelioma (MPM) is an uncommon disease most often associated with occupational asbestos exposure and is steadily increasing in worldwide incidence. Patients typically present at an older age, with advanced clinical stage and other medical comorbidities, making management quite challenging. Despite great efforts, the prognosis of MPM remains poor, especially at progression after initial treatment. Macroscopic complete resection of MPM can be achieved through extrapleural pneumonectomy (EPP) or extended (ie, radical) pleurectomy (e-P/D) in selected patients and can result in prolonged survival when incorporated into a multimodality approach. Given the morbidity associated with surgical resection of MPM, optimizing identification of appropriate patients is essential. Unfortunately, most patients are not candidates for EPP or e-P/D due to advanced stage, age, and/or medical comorbidity. Pemetrexed and platinum combination chemotherapy has become the cornerstone of therapy for patients with unresectable disease because the combination is associated with improved survival and quality of life in treated patients. However, MPM eventually becomes resistant to initial therapy, and benefit to further lines of therapy has not been substantiated in randomized clinical trials. Translational research has provided exciting insights into tumorigenesis, biomarkers, and immune response in MPM, leading to the development of multiple novel therapeutic agents that are currently in clinical trials. These advances hold the promise of a new era in the treatment of MPM and suggest that this disease will not be left behind in the war on cancer.

Second malignant neoplasms and cardiovascular disease following radiotherapy

Second malignant neoplasms (SMNs) and cardiovascular disease (CVD) are among the most serious and life-threatening late adverse effects experienced by the growing number of cancer survivors worldwide and are due in part to radiotherapy. The National Council on Radiation Protection and Measurements (NCRP) convened an expert scientific committee to critically and comprehensively review associations between radiotherapy and SMNs and CVD, taking into account radiobiology; genomics; treatment (i.e., radiotherapy with or without chemotherapy and other therapies); type of radiation; and quantitative considerations (i.e., dose-response relationships). Major conclusions of the NCRP include: (1) the relevance of older technologies for current risk assessment when organ-specific absorbed dose and the appropriate relative biological effectiveness are taken into account and (2) the identification of critical research needs with regard to newer radiation modalities, dose-response relationships, and genetic susceptibility. Recommendation for research priorities and infrastructural requirements include (1) long-term large-scale follow-up of extant cancer survivors and prospectively treated patients to characterize risks of SMNs and CVD in terms of radiation dose and type; (2) biological sample collection to integrate epidemiological studies with molecular and genetic evaluations; (3) investigation of interactions between radiotherapy and other potential confounding factors, such as age, sex, race, tobacco and alcohol use, dietary intake, energy balance, and other cofactors, as well as genetic susceptibility; (4) focusing on adolescent and young adult cancer survivors, given the sparse research in this population; and (5) construction of comprehensive risk prediction models for SMNs and CVD to permit the development of follow-up guidelines and prevention and intervention strategies.

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.

Asbestos-related pleuropulmonary diseases: benign and malignant

Asbestos is known for its desirable properties of thermal and heat resistance along with excellent strength and durability. It was widely used in many industries since the late 19th century, until its adverse effects on health were recognized. The occurrence of pleuropulmonary changes from exposure to asbestos often has a latency period of 20 to 30 years. The use of asbestos has been banned, regulated, and minimized in many countries, but in several developing countries, the use of asbestos in industries is still a common practice. In this article, the benign and malignant clinical manifestations of asbestos exposure are discussed.

Mesothelioma not associated with asbestos exposure

CONTEXT

Despite asbestos being identified as the single most important cause of malignant mesothelioma, the tumor is known to occur in only 10% to 20% of heavily exposed individuals. In addition, about 20% of the patients have no history of asbestos exposure even after detailed assessment. Therefore, there has been speculation for some time that asbestos alone may not be sufficient to cause mesothelioma and that other factors may be involved either as cocarcinogens or as independent mechanisms of cancer causation.

OBJECTIVE

To give a brief review of nonasbestos fiber erionite and therapeutic radiation as 2 established examples of asbestos-independent mechanisms, of the potential emerging role of man-made fibers such as carbon nanotubes, and of polyoma virus SV40 (simian virus 40) as a potential example of the cocarcinogenic mode of involvement.

DATA SOURCES

Relevant recent literature has been surveyed to portray and provide the evidence in favor of the examples.

CONCLUSIONS

Erionite has emerged as the most important example of nonasbestos-mediated cause of mesothelioma in regions such as Turkey where exposure to this type of fiber is highly prevalent. Recently, the polyoma virus SV40 has been unexpectedly discovered as an effective cocarcinogen of asbestos in the causation of animal mesothelioma, though despite considerable research, its potential role in human mesothelioma remains unproven.

Second malignant neoplasms and cardiovascular disease following radiotherapy

Second malignant neoplasms (SMNs) and cardiovascular disease (CVD) are among the most serious and life-threatening late adverse effects experienced by the growing number of cancer survivors worldwide and are due in part to radiotherapy. The National Council on Radiation Protection and Measurements (NCRP) convened an expert scientific committee to critically and comprehensively review associations between radiotherapy and SMNs and CVD, taking into account radiobiology; genomics; treatment (ie, radiotherapy with or without chemotherapy and other therapies); type of radiation; and quantitative considerations (ie, dose-response relationships). Major conclusions of the NCRP include: 1) the relevance of older technologies for current risk assessment when organ-specific absorbed dose and the appropriate relative biological effectiveness are taken into account and 2) the identification of critical research needs with regard to newer radiation modalities, dose-response relationships, and genetic susceptibility. Recommendation for research priorities and infrastructural requirements include 1) long-term large-scale follow-up of extant cancer survivors and prospectively treated patients to characterize risks of SMNs and CVD in terms of radiation dose and type; 2) biological sample collection to integrate epidemiological studies with molecular and genetic evaluations; 3) investigation of interactions between radiotherapy and other potential confounding factors, such as age, sex, race, tobacco and alcohol use, dietary intake, energy balance, and other cofactors, as well as genetic susceptibility; 4) focusing on adolescent and young adult cancer survivors, given the sparse research in this population; and 5) construction of comprehensive risk prediction models for SMNs and CVD to permit the development of follow-up guidelines and prevention and intervention strategies.

Second Cancer Risk After Chemotherapy for Hodgkin's Lymphoma: A Collaborative British Cohort Study

Purpose

We investigated the long-term risk of second primary malignancy after chemotherapy for Hodgkin's lymphoma (HL) in a much larger cohort than any yet published, to our knowledge.

Patients and Methods

We followed 5,798 patients with HL treated with chemotherapy in Britain from 1963 to 2001—of whom 3,432 also received radiotherapy—to assess second primary malignancy risks compared with general population-based expectations.

Results

Second malignancies occurred in 459 cohort members. Relative risk (RR) of second cancer was raised after chemotherapy alone (RR, 2.0; 95% CI, 1.7 to 2.4) but was much lower than after combined modalities (RR, 3.9; 95% CI, 3.5 to 4.4). After chemotherapy alone, there were significantly raised risks of lung cancer, non-HL, and leukemia, each contributing approximately equal absolute excess risk. After combined modalities, there were raised risks of these and several other cancers. Second cancer risk peaked 5 to 9 years after chemotherapy alone, but it remained raised for 25 years and longer after combined modalities. Risk was raised after each common chemotherapy regimen except, based on limited numbers and follow-up, adriamycin, bleomycin, vinblastine, and dacarbazine. The age and time-course relations of lung cancer differed between chemotherapy alone and combined modalities.

Conclusion

Although chemotherapy alone leads to raised risk of second malignancy, this risk is lower and affects fewer anatomic sites than that after combined modalities, and it is slight if at all after 15 years follow-up. The mechanism of lung cancer etiology may differ between chemotherapy and radiotherapy.

Long-Term Complications of Lymphoma and Its Treatment

As a result of therapeutic advances, there is a growing population of survivors of both Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). A thorough understanding of the late effects of cancer and its treatment, including the risk of developing a second malignancy and non-neoplastic complications, most notably cardiac disease, is essential for the proper long-term follow-up care of these patients. For HL survivors cured in the past 5 decades, a large body of literature describes a range of long-term effects, many of which are related to extent of treatment. These studies form the basis for many of the follow-up recommendations developed for HL survivors. As HL therapy continues to evolve, however, with an emphasis toward treatment reduction, in particular for early-stage disease, it will be important to rigorously observe this new generation of patients long term to document and quantify late effects associated with modern treatments. Although data on late effects after NHL therapy have recently emerged, the formulation of structured follow-up plans for this heterogeneous group of survivors is challenging, given the highly variable natural history, treatments, and overall prognosis. However, the chemotherapy and radiation therapy approaches for some types of NHL are similar to that for HL; thus, some of the follow-up guidelines for patients with HL may also be transferrable to selected survivors of NHL. Additional work focused on treatment-related complications after NHL will facilitate the development of follow-up programs, as well as treatment refinements to minimize late effects in patients with various types of NHL.

Risk for second malignancies in non-Hodgkin's lymphoma survivors: a meta-analysis

BACKGROUND

Late side-effects are becoming an important issue in non-Hodgkin's lymphoma (NHL) survivors. We intended to estimate pooled relative risk (RR) of secondary malignant neoplasms (SMNs), to evaluate site-associated RR and the impact of different treatments.

DESIGN

We carried out an electronic search of Medline and EMBASE seeking articles investigating the risk of SMNs and reporting RR measures. The studies were evaluated for heterogeneity before meta-analysis and for publication bias. Pooled RRs were estimated using fixed- and random-effects models.

RESULTS

A total of 23 studies met the inclusion criteria. Pooled RRs of SMNs overall and for solid tumors were 1.88 and 1.32, respectively. We found an excess of risk for several specific cancer sites. Radiotherapy alone did not increase the risk for SMNs, while chemotherapy and combined treatments augmented the RR. Regression analyses revealed a positive significant association for all SMNs with total body irradiation, and for solid SMNs with younger age. No publication bias was observed.

CONCLUSIONS

Our results indicate that NHL patients experience a higher risk for SMNs than the general population and that various treatments have different impact on RR. More information will be necessary to evaluate possible interactions with genetic susceptibility and environmental exposure.

Advances in the biology of malignant pleural mesothelioma

Malignant pleural mesothelioma is a highly aggressive cancer with a very poor prognosis. Although the mechanism of carcinogenesis is not fully understood, approximately 80% of malignant pleural mesothelioma can be attributed to asbestos fiber exposure. This disease is largely unresponsive to conventional chemotherapy or radiotherapy, and most patients die within 10-17 months of their first symptoms. Currently, malignant pleural mesothelioma therapy is guided by clinical stage and patient characteristics rather than by the histological or molecular features of the tumor. Several molecular pathways involved in malignant pleural mesothelioma have been identified; these include cell cycle regulation, apoptosis, growth factor pathways, and angiogenesis. Unfortunately, several agents targeting these processes, including erlotinib, gefitinib, and imatinib, have proven ineffective in clinical trials. A greater understanding of the molecular pathways involved in malignant pleural mesothelioma is needed to develop better diagnostics, therapeutics, and preventative measures. Moreover, understanding the biological basis of mesothelioma progression may facilitate personalized treatment approaches, and early identification of poor prognostic indicators may help reduce the heterogeneity of the clinical response. This paper reviews advances in the molecular biology of malignant pleural mesothelioma in terms of pathogenesis, the major molecular pathways and the associated therapeutic strategies, and the roles of biomarkers.

Second surgery for recurrence of malignant pleural mesothelioma after extrapleural pneumonectomy

BACKGROUND

Extrapleural pneumonectomy is a treatment option for malignant pleural mesothelioma (MPM), but disease recurrence is common. Among different therapeutic options for recurrence, we have found no reports for second surgical procedures.

METHODS

We retrospectively evaluated the types and outcomes of surgical management of solid recurrences of MPM, in a series of 74 patients treated with extrapleural pneumonectomy over a 20-year period.

RESULTS

Of 57 patients for whom follow-up data were available, 11 patients experienced recurrent disease in the form of a solid mass, 1.5 to 12 years after the initial treatment; 8 of these patients had sufficiently good clinical conditions to undergo a second surgery with curative intent. Chest wall resection was performed in 4 cases of parietal recurrence, radical retroperitoneal resection was done in 3 cases of retroperitoneal relapse, and segmental resection of the remaining lung was done in one case of pulmonary metastasis. In this latter case, although computed tomographic images showed a solid mass, at surgery the disease was found to have a serosal nature, precluding the possibility of a curative surgery. Median survival after the second surgery was 14.5 months (range, 6 to 29); no association between survival and site of recurrence, age or disease-free interval was found.

CONCLUSIONS

In this series, the second surgery did not offer the expected survival benefit of curative treatment strategies and should therefore be considered palliative. Second surgery may be a treatment option in a subset of patients who experience a solid recurrence of MPM that is symptomatic or near vital organs and who cannot undergo additional radiotherapy.

Time trend of mesothelioma incidence in the United States and projection of future cases: an update based on SEER data for 1973 through 2005

The time trend of mesothelioma incidence and projections of future cases provide useful information for analyzing proposed public health interventions where asbestos exposure may be an issue, evaluating regulatory proposals, and estimating the remaining potential costs of programs to compensate individuals with asbestos-related diseases. We used the April 2008 release of Surveillance, Epidemiology, and End Results (SEER) data, which covers 1973 through 2005, to analyze the time trends in age-adjusted mesothelioma incidence and to estimate an age and birth-cohort model to project the number of future mesothelioma cases. The increase in the number of SEER cancer registries from 13 to 17 in 2000 had little effect on the time pattern of age-adjusted mesothelioma incidence, and the pattern over time of pleural mesothelioma was indistinguishable from the pattern for total mesothelioma defined as sum of pleural and peritoneal cases. Our analysis suggests that the SEER registries viewed as a sample of the U.S. population over-represents high mesothelioma incidence, a fact that we accounted for in our projections. For 2008 we estimate approximately 2,400 cases, with asbestos the likely cause in 58%. We project that asbestos will no longer be a factor in mesothelioma cases after the year 2042. For 2008 through 2042, we estimate slightly more than 68,000 total cases, with asbestos the likely cause in 34%.

French cohort of the uranium processing workers: mortality pattern after 30-year follow-up

OBJECTIVE

To investigate mortality among nuclear workers with potential internal exposure to uranium.

METHODS

The cohort included 2,709 workers employed at the AREVA NC Pierrelatte plant for at least 6 months (72,787 person-years). This plant processed uranium enrichment during the period 1960-1996 and chemical conversion since 1980. Mortality was compared to the national and regional mortality rates available for the period 1968-2005. For causes of death of interest with respect to occupational exposure, mortality trends according to occupational characteristics were assessed.

RESULTS

As expected, an important healthy worker effect (all causes SMR = 0.55 (95% CI: 0.50-0.61), n = 411; all cancers SMR = 0.70 (95% CI: 0.60-0.81), n = 193) was observed. Among cancer sites a priori related to uranium exposure, only mortality for lymphatic cancer was increased among potentially exposed workers (SMR = 1.49 (95% CI: 0.68-2.82); n = 9). An important increase in mortality from pleural cancer was observed (SMR = 2.85 (95% CI: 0.93-6.66), n = 5); none of the deceased workers were exposed to radiation whereas all handled asbestos.

CONCLUSION

In spite of limited statistical power, results show consistency with previous studies of nuclear workers potentially exposed to uranium. Further investigation based on more precise uranium exposure data should allow the estimation of uranium hazard effects among this cohort.

Malignant mesothelioma after radiation treatment for Hodgkin lymphoma

Malignant mesothelioma is a relatively uncommon malignancy. Although the pathogenesis is primarily related to asbestos, the disease may be associated with radiation exposure. Recently, increased risks for second primary mesothelioma after radiation for lymphoma have been reported. Because these findings are based on small numbers of patients, they need to be confirmed. We examined mesothelioma risk in 2567 5-year survivors of Hodgkin lymphoma. The risk was almost 30-fold increased in Hodgkin lymphoma patients treated with irradiation compared with the general population. Although histology and survival of the mesothelioma cases were comparable with cases from the general population, asbestos exposure and the proportion of males were lower than expected. The evidence for radiotherapy as cause for mesothelioma independent of exposure to asbestos is expanding, and the diagnosis of mesothelioma should be kept in mind whenever related symptoms arise in patients who had previous irradiation.

US mesothelioma patterns 1973-2002: indicators of change and insights into background rates

Mesothelioma rates are declining toward background levels, although estimates of the background rate have varied. We expanded upon earlier analyses and provided a data-based estimate of the background rate. We analyzed US male and female patterns for five age groups using the National Cancer Institute's Surveillance Epidemiology and End Results registry data from 1973 to 2002. Age-specific and age-adjusted incidence rates per 1 000 000 persons per year, standardized to the 2000 US population, were calculated for total, pleural, and peritoneal mesothelioma. We also calculated rates for persons who attained working age after the US Occupational Safety and Health Administration asbestos exposure limits took effect. Mesothelioma rates observed among young males and females varied little over time. We observed a decline and convergence of recent male and female rates in older age groups, except those who are between the age of 60 and above, for whom the 2002 male rate was approximately five times greater than that of females. As expected, rates were higher in major shipyard areas on the West coast. Rates for persons with little or no opportunity for occupational asbestos exposure were 1.15 (95% confidence interval: 0.90-1.45) for men and 0.94 (95% confidence interval: 0.87-1.24) for women. Mesothelioma is rare in younger age groups, and rates have been relatively stable and similar for both sexes. Rates continue to decline in older age groups, but remain high for males at 60 years or older. Rates among females at older ages suggest an impact of occupational exposure. The background rate for persons below age 50 is approximately one per million, independent of sex. Future data are needed to estimate this rate for older age groups.