RELATION BETWEEN EXPOSURE TO ASBESTOS AND MESOTHELIOMA

Microbe-Mineral Interactions between Asbestos and Thermophilic Chemolithoautotrophic Anaerobes

The Fe content and the morphometry of asbestos are two major factors linked to its toxicity. This study explored the use of microbe-mineral interactions between asbestos (and asbestos-like) minerals and thermophilic chemolithoautotrophic microorganisms as possible mineral dissolution treatments targeting their toxic properties. The removal of Fe from crocidolite was tested through chemolithoautotrophic Fe(III) reduction activities at 60°C. Chrysotile and tremolite-actinolite were tested for dissolution and potential release of elements like Si and Mg through biosilicification processes at 75°C. Our results show that chemolithoautotrophic Fe(III) reduction activities by Deferrisoma palaeochoriense were supported with crocidolite as the sole source of Fe(III) used as a terminal electron acceptor during respiration. Microbial Fe(III) reduction activities resulted in higher Fe release rates from crocidolite in comparison to previous studies on Fe leaching from crocidolite through Fe assimilation activities by soil fungi. Evidence of biosilicification in Thermovibrio ammonificans did not correspond with increased Si and Mg release from chrysotile or tremolite-actinolite dissolution. However, overall Si and Mg release from chrysotile into our experimental medium outmatched previously reported capabilities for Si and Mg release from chrysotile by fungi. Differences in the profiles of elements released from chrysotile and tremolite-actinolite during microbe-mineral experiments with T. ammonificans underscored the relevance of underlying crystallochemical differences in driving mineral dissolution and elemental bioavailability. Experimental studies targeting the interactions between chemolithoautotrophs and asbestos (or asbestos-like) minerals offer new access to the mechanisms behind crystallochemical mineral alterations and their role in the development of tailored asbestos treatments. IMPORTANCE We explored the potential of chemosynthetic microorganisms growing at high temperatures to induce the release of key elements (mainly iron, silicon, and magnesium) involved in the known toxic properties (iron content and fibrous mineral shapes) of asbestos minerals. We show for the first time that the microbial respiration of iron from amphibole asbestos releases some of the iron contained in the mineral while supporting microbial growth. Another microorganism imposed on the two main types of asbestos minerals (serpentines and amphiboles) resulted in distinct elemental release profiles for each type of asbestos during mineral dissolution. Despite evidence of microbially mediated dissolution in all minerals, none of the microorganisms tested disrupted the structure of the asbestos mineral fibers. Further constraints on the relationships between elemental release rates, amount of starting asbestos, reaction volumes, and incubation times will be required to better compare asbestos dissolution treatments studied to date.

From hazardous asbestos containing wastes (ACW) to new secondary raw material through a new sustainable inertization process: A multimethodological mineralogical study

Nowadays, asbestos-containing wastes (ACW) still represent an important environmental problem and a severe health hazard due to the well known pulmonary diseases derived from asbestos fibers inhalation. Except for a very few cases, ACW are currently confined in controlled landfills, giving rise to increasingly high amounts of still hazardous wastes. A promising alternative to landfill confinement is represented by ACW inertization, but the high cost of the inertization processes so far proposed by the scientific community have hampered the creation of actually operative plants. In this paper, we explore the possibility to use an innovative process that ensures the obtainment of asbestos-free inert material in an exceptionally short processing time, thus greatly reducing cost-related problems. The efficacy of the inertization process has been verified through accurate mineralogical investigations on both chrysotile and crocidolite de-activated fibers, through X-ray diffraction, scanning and transmission electron microscopy. Overall mineralogical, microstructural and granulometric characteristics of the inert bulk material suggest that it could be successfully re-used as a secondary raw material in ceramic industries. This innovative inertization procedure could therefore provide an effective and economically sustainable solution for ACW management.

The Role of Hyperthermic Intraperitoneal Chemotherapy for Non-colorectal Peritoneal Surface Malignancies

BACKGROUND

Peritoneal carcinomatosis, from a variety of gastrointestinal and gynecological malignancies, has been historically challenging to treat and there remains a wide range of biologic aggressiveness in these patients. Malignancies commonly associated with PC include those of colorectal, appendiceal, gastric, ovarian, sarcoma, small intestinal, and primary peritoneal origin among others. Advances in our understanding of this unique disease process have led to significant interest in cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) as an emerging treatment option. The goal of CRS-HIPEC is to remove all visible macroscopic disease while preserving organ function, and then treat microscopic disease through perfusion of the peritoneal cavity with heated chemotherapy.

PURPOSE

Although recent reviews have focused on the management of peritoneal carcinomatosis secondary to colorectal cancer given the publication of several recent randomized controlled trials, the purpose of the current review is to summarize the evidence on CRS-HIPEC for non-colorectal peritoneal surface malignancies, including appendiceal neoplasms, malignant peritoneal mesothelioma, gastric cancer, and ovarian cancer.

RESULTS

While retrospective studies have clarified the importance of prognostic factors such as the peritoneal carcinomatosis index, completeness of cytoreduction, histopathological characteristics, and lymph node positivity, the lack of convincing level 1 evidence for the use of CRS-HIPEC has led to it remaining a highly controversial topic.

CONCLUSION

The decision to utilize CRS-HIPEC should involve a multidisciplinary team approach and evaluation of prognostic factors to balance the short-term morbidity of the operation with maximum long-term benefits. Large, multi-institutional groups and ongoing trials hold promise for clarifying the role of CRS-HIPEC in peritoneal surface malignancies.

Irinotecan and Gemcitabine as Second-Line Treatment in Patients with Malignant Pleural Mesothelioma following Platinum plus Pemetrexed Chemotherapy: A Retrospective Study

BACKGROUND

Cisplatin-pemetrexed combination chemotherapy is the current standard primary treatment for malignant pleural mesothelioma (MPM). It was first approved for untreated and unresectable MPM in the 2003 National Comprehensive Cancer Network (NCCN) guidelines. However, to date, standard treatments for patients with MPM who previously underwent chemotherapy, as recommended by the NCCN Malignant Pleural Mesothelioma guidelines, have been inadequate. To explore treatment options for such patients, we performed this retrospective study of patients who received irinotecan plus gemcitabine as second-line therapy for MPM.

METHODS

We investigated 62 patients diagnosed with unresectable MPM between January 2008 and October 2017 who experienced recurrence following cisplatin treatment (or carboplatin) plus pemetrexed or pemetrexed monotherapy as first-line treatment, and who underwent irinotecan plus gemcitabine combination therapy as second-line treatment. Irinotecan (60 mg/m2) and gemcitabine (800 mg/m2) were administered on days 1 and 8 every 3 weeks, including a 1-week washout period. Our endpoints were efficacy, survival period, and toxicity.

RESULTS

patients' median age was 65 years (range 50-79), and the histological MPM types were epithelioid (n = 48), sarcomatoid (n = 6), biphasic (n = 6), and desmoplastic (n = 2). One patient experienced a partial response, 40 had stable disease, and 21 had progressive disease. The disease control rate was 66.1% and the response rate 2.1%. Additionally, the median progression-free and overall survival time were 5.7 and 11.3 months, respectively. The most common adverse events were neutropenia (32.2%), loss of appetite (16.1%), nausea/diarrhea (11.3%), and thrombocytopenia/phlebitis (9.7%). Grade 3 adverse events included neutropenia (12.9%) and thrombocytopenia/phlebitis (2.1%); however, all adverse events were managed with symptomatic therapy.

CONCLUSIONS

Despite the fact that second-line irinotecan plus gemcitabine combination therapy did not produce marked tumor shrinkage, it achieved a relatively high disease control rate of >65% with an acceptable toxicity profile. Hence, the combination of irinotecan plus gemcitabine may be considered for MPM treatment, with consideration of combination with immune checkpoint inhibitors as a potential next step.

Single-Cell Analysis Reveals that Chronic Silver Nanoparticle Exposure Induces Cell Division Defects in Human Epithelial Cells

Multiple organizations have urged a paradigm shift from traditional, whole animal, chemical safety testing to alternative methods. Although these forward-looking methods exist for risk assessment and predication, animal testing is still the preferred method and will remain so until more robust cellular and computational methods are established. To meet this need, we aimed to develop a new, cell division-focused approach based on the idea that defective cell division may be a better predictor of risk than traditional measurements. To develop such an approach, we investigated the toxicity of silver nanoparticles (AgNPs) on human epithelial cells. AgNPs are the type of nanoparticle most widely employed in consumer and medical products, yet toxicity reports are still confounding. Cells were exposed to a range of AgNP doses for both short- and-long term exposure times. The analysis of treated cell populations identified an effect on cell division and the emergence of abnormal nuclear morphologies, including micronuclei and binucleated cells. Overall, our results indicate that AgNPs impair cell division, not only further confirming toxicity to human cells, but also highlighting the propagation of adverse phenotypes within the cell population. Furthermore, this work illustrates that cell division-based analysis will be an important addition to future toxicology studies.

Prevention of Asbestos Exposure in Latin America within a Global Public Health Perspective

Background:

Asbestos consumption in Latin America (LA) amounts to 10% of yearly global production. Little is known about the impact of asbestos exposure in the region.

Objective:

To discuss scientific and socio-economic issues and conflicts of interest and to summarize epidemiological data of asbestos health effects in LA.

Discussion:

Recent data on chrysotile strengthened the evidence of its carcinogenicity and showed an excessive risk of lung cancer at cumulative exposure levels as low as 1.5 fibre-years/ml. Technology for substitution is available for all asbestos-containing products and ceasing asbestos production and manufacturing will not result in unemployment and loss of income, except for the mining industry. The flawed arguments used by the industry to maintain its market, both to the public and in courtrooms, strongly relies on the lack of local evidence of the ill effects and on the invisibility of asbestos-related diseases in LA, due to the limited number of studies and the exposed workers’ difficulty accessing health services. The few epidemiological studies available show clear evidence of clusters of mesothelioma in municipalities with a history of asbestos consumption and a forecasted rise in its incidence in Argentina and Brazil for the next decade. In Brazil, non-governmental organizations of asbestos workers were pivotal to counterbalance misinformation and inequities, ending recently in a Supreme Court decision backing an asbestos ban. In parallel, continuous efforts should be made to stimulate the growth of competent and ethical researchers to convey adequate information to the scientific community and to the general public.

Mortality among workers exposed to asbestos at the shipyard of Genoa, Italy: a 55 years follow-up

BACKGROUND

Exposure to asbestos remains a global issue due to its massive use in the twentieth century and its long environmental persistence. Exposure to asbestos still occurs during dismantling of ships and vessels, buildings renovation, mining operations, and is reported in developing countries. Current estimate report exposure of hundreds of million people in occupational settings in countries where its use remains unregulated.

METHODS

We conducted a historical prospective cohort mortality study aimed at estimating mortality from specific causes, the temporal changes of pleural and lung cancer mortality, and the attributable fraction (AF) of lung cancer deaths following asbestos exposure. The study included 3984 shipyard workers employed at the shipyard of Genoa, Italy, between 1960 and 1981 and followed up to December 2014. Standardized Mortality Ratios (SMR) and their 95% confidence intervals (95%CI) were computed.

RESULTS

Overall deaths recorded were 3331 (83.6%). Excess mortality was observed for all cancers (SMR = 127, 95%CI:120-134), pleural mesothelioma (575, 469-697), cancers of the larynx (183, 134-244) and of the lung (154, 139-170), and for respiratory tract diseases (127, 114-141), including asbestosis (2277, 1525-3270). Ninety out of 399 deaths (22.6%) from lung cancer were attributed to asbestos exposure. The estimated lung cancer AF was 49.3% in workers with the highest SMR for pleural cancer. Median latency times for pleural and lung cancer were 42.8 years (minimum latency: 9.3 years) and 38.7 years (minimum latency: 6 years). The peak of mesothelioma incidence, expected in Italy in the period 2015-2024, was confirmed.

CONCLUSIONS

The long follow-up period of our study allowed the detection of a substantial disease burden following asbestos exposure. These findings support the urgent need for the prevention of asbestos related diseases through the implementation of asbestos ban worldwide, including those countries where asbestos is still mined, manufactured and used.

Peritoneal Metastases from Malignant Mesothelioma

Diffuse malignant peritoneal mesothelioma (MPM) is a rare cancer that is ultimately fatal in almost all afflicted individuals. Morbidity and mortality from MPM is due to its propensity to progress locoregionally within the abdominal cavity. Patients with MPM most commonly present with nonspecific abdominal symptoms that usually lead to diagnosis when the condition is relatively advanced. MPM is considered a chemotherapy-resistant malignancy.

Malignant Peritoneal Mesothelioma

Eight cases of peritoneal malignant mesothelioma observed at the Istituto Nazionale Tumori of Milan from 1972 to 1978 are reported. The clinical features of the cases clearly point out the diagnostic difficulties, the inadequacy of the treatment and the poor prognosis of this neoplasia. The authors maintain that more complete epidemiologic studies and more adequate therapeutic programs could modify the prognosis for this neoplasm.

Histology of Chemically Induced Mesotheliomas in Mrc-wistar Rats

Two peritoneal mesotheliomas were induced in rats during a carcinogenicity study of 1-nitroso-5,6-dihydrouracil (NO-DHU) injected intraperitoneally. A review of literature concerning experimental induction of such tumors indicated that they seldom produced with organic compounds and rarely occur spontaneously. In the present study, several reports of chemically induced mesotheliomas of the testes are analyzed and the diagnoses critically reviewed along with other differential diagnoses.

The Medicalization of Health and Shared Responsibility

Public, occupational and environmental health are relatively novel disciplines compared to the ancient history of medicine. Their development, together with a more insightful knowledge of the human pathophysiology (this more usual term is the one used in the article itself), have progressively expanded the field of investigation of medicine to environmental, behavioural and genetic factors that favour the development of certain medical conditions. As a result we have developed numerous additional strategies to monitor health and prevent disease, including interventions in anticipation of diseases themselves when patients are still healthy or in a grey area of increased risk. New developments related to genomics and distributed point of care technologies will exacerbate a process of medicalization of health. This process is profoundly re-shaping how medicine interacts with the general population, states and policy makers and has implications for healthcare system design and individual health choices.

Diffuse peritoneal mesothelioma: A case series of 62 patients including paraoccupational exposures to chrysotile asbestos

BACKGROUND

Diffuse peritoneal malignant mesothelioma (DPM) is caused by exposure to asbestos. The medical literature has linked DPM primarily to high levels of asbestos exposure, in particular amosite. Controversy persists as to whether chrysotile is capable of causing DPM, especially when exposures are paraoccupational.

METHODS

Sixty-two subjects (51 men, 11 women) with DPM were reviewed in medical-legal consultation with deposition and product identification evidence.

RESULTS

All had pathologically confirmed DPM. Most were exposed to both amphibole and chrysotile, but chrysotile alone was documented in 14/62 (26%) cases. A total of 7/14 (50%) cases of the paraoccupational exposures were to chrysotile alone. Women were younger than men as were those with paraoccupational versus those with occupational exposure. The mean duration of exposure for all cases was 17.9 ± 10 years and latency from time of first exposure was 45.9 + 11.6 years.

CONCLUSIONS

DPM occurs with both occupational and paraoccupational exposures to asbestos and may be seen in paraoccupational exposures to chrysotile asbestos.

Reflections on the history of indoor air science, focusing on the last 50 years

The scientific articles and Indoor Air conference publications of the indoor air sciences (IAS) during the last 50 years are summarized. In total 7524 presentations, from 79 countries, have been made at Indoor Air conferences held between 1978 (49 presentations) and 2014 (1049 presentations). In the Web of Science, 26 992 articles on indoor air research (with the word "indoor" as a search term) have been found (as of 1 Jan 2016) of which 70% were published during the last 10 years. The modern scientific history started in the 1970s with a question: "did indoor air pose a threat to health as did outdoor air?" Soon it was recognized that indoor air is more important, from a health point of view, than outdoor air. Topics of concern were first radon, environmental tobacco smoke, and lung cancer, followed by volatile organic compounds, formaldehyde and sick building syndrome, house dust-mites, asthma and allergies, Legionnaires disease, and other airborne infections. Later emerged dampness/mold-associated allergies and today's concern with "modern exposures-modern diseases." Ventilation, thermal comfort, indoor air chemistry, semi-volatile organic compounds, building simulation by computational fluid dynamics, and fine particulate matter are common topics today. From their beginning in Denmark and Sweden, then in the USA, the indoor air sciences now show increasing activity in East and Southeast Asia.

A case of malignant peritoneal mesothelioma suggesting the utility of combining double-contrast radiography and endoscopy with computed tomography for diagnosis

A 68-year-old woman presented with abdominal pain, weight loss, and vomiting. Enhanced computed tomography (CT) showed slightly increased density in the mesentery and edema of the third portion of the duodenum and proximal jejunum. Little ascites, but no primary lesion, lymph node metastases, or distant metastases, were observed. Endoscopic findings included erythema and edema in the distal duodenum and proximal jejunum without epithelial lesions. Double-contrast radiography revealed transverse ridging with convergence, suggesting a serosal lesion. We suspected disease involving the serosa, such as mesenteric panniculitis. However, the lesion was definitively diagnosed as malignant peritoneal mesothelioma based on a biopsy specimen obtained at laparotomy. The combination of transverse ridging with convergence on double-contrast radiography and mucosal edema without epithelial lesions on endoscopy was consistent with a disorder involving the serosa. Transverse ridging with convergence is helpful to diagnose serosal pathology such as malignant peritoneal mesothelioma. Combining the findings of double-contrast radiography and endoscopy with computed tomography may facilitate diagnosis of malignant peritoneal mesothelioma. Thus, in case of increased density of mesentery and wall thickness on CT image with transverse ridging with convergence on double-contrast radiography and without epithelial lesion on endoscopy, malignant peritoneal mesothelioma must be considered.

History of knowledge and evolution of occupational health and regulatory aspects of asbestos exposure science: 1900-1975

The understanding by industrial hygienists of the hazards of asbestos and appropriate ways to characterize and control exposure has evolved over the years. Here, a detailed analysis of the evolution of industrial hygiene practices regarding asbestos and its health risks, from the early 1900s until the advent of the national occupational health and safety regulatory structure currently in place in the US (early-to-mid 1970s) is presented. While industrial hygienists recognized in the early 1900s that chronic and high-level exposures to airborne concentrations of asbestos could pose a serious health hazard, it was not until the mid-1950s that the carcinogenic nature of asbestos began to be characterized and widespread concern followed. With the introduction of the membrane filter sampling method in the late 1960s and early 1970s, asbestos sampling and exposure assessment capabilities advanced to a degree which allowed industrial hygienists to more precisely characterize the exposure-response relationship. The ability of industrial hygienists, analytical chemists, toxicologists, and physicians to more accurately define this relationship was instrumental to the scientific community's ability to establish Occupational Exposure Levels (OELs) for asbestos. These early developments set the stage for decades of additional study on asbestos exposure potential and risk of disease. This was followed by the application of engineering controls and improved respiratory protection which, over the years, saved thousands of lives. This paper represents a state-of-the-art review of the knowledge of asbestos within the industrial hygiene community from about 1900 to 1975.

[Surgical therapy of malignant pleural mesothelioma]

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor disease, which rapidly leads to death if untreated. In Germany the incidence of newly occurring disease is expected to reach a peak in the coming 5 years. An R0 resection for MPM is technically impossible; therefore, the aim of surgical procedures is to achieve the maximum amount of cytoreduction. There are two established surgical techniques for treatment of MPM, extrapleural pneumonectomy and tumor pleurectomy with decortication. The type and extent of surgery are currently controversially discussed. Within multimodal therapy concepts including cytoreductive surgery, long-term remission is possible in selected patients. When choosing the appropriate surgical therapy the high incidence of recurrence has to be borne in mind.

Diagnosis and management of patients with malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma (MPM) is a rare neoplastic condition that arises, usually diffusely, from the serosal membranes of the abdominal cavity. MPM represents about 7% to 10% of all mesothelioma diagnoses and this translates into approximately 800 cases per year in the United States. The disease has variable tumor biology but progression, when it occurs, is almost always within the abdominal cavity. Although many patients can be successfully treated at initial presentation, the disease is almost always fatal in time. It afflicts men and women almost equally and the median age at presentation is 50 years. The diagnosis is made when a diffuse malignant process within the abdominal cavity is observed and a tissue sample reveals the characteristic histopathology and immunohistochemical profile of mesothelioma. Initial staging is usually via a cross sectional imaging study of the abdomen and pelvis making sure that the lower thorax is also assessed. If the disease burden and distribution is favorable then operative exploration, cytoreduction, and hyperthermic intraperitoneal chemotherapy (HIPEC) are considered first line treatment in selected patients. Systemic pemetrexed and cisplatin (or gemcitabine) have modest response rates that are of limited duration. Research advances with novel systemic or intraperitoneal agents hold promise.

Fiber analysis vignettes: Electron microscopy to the rescue!

There has been considerable interest in the exposure doses that contribute to the various asbestos-associated diseases. Epidemiological studies have shown important differences in the contributions of the various fiber types to asbestos-related diseases, with the amphiboles showing a greater degree of potency as compared to chrysotile. However, epidemiological studies have occasionally provided misleading results. Over the past several decades, there have been several examples where fiber analysis using electron microscopy produced unexpected results which were important to our understanding of disease-exposure relationships. It is the purpose of this article to summarize these fiber analysis vignettes.

Multimodality therapy for malignant pleural mesothelioma: surgery plus chemoradiotherapy?

Malignant pleural mesothelioma, well known for its association with asbestos exposure, is an aggressive cancer of the pleura with poor prognosis if left untreated. There is no defined standard of care, but with curative surgery-based multimodality therapy, long-term survival has been documented. In addition to radiation and/or chemotherapy, multimodality therapy includes one of two operations (extrapleural pneumonectomy or radical pleurectomy/decortication) performed with the goal of resecting all gross disease. Ongoing trials are evaluating various treatment strategies involving radical resection, chemotherapy, radiation, intracavitary chemotherapy, photodynamic therapy and immunologic/biologic agents. Improvement in early diagnosis, targeted treatment and adjuvant therapy to control micrometastatic disease are needed to improve outcomes for patients with this challenging disease.

On Corporate Accountability: Lead, Asbestos, and Fossil Fuel Lawsuits

This paper examines the use of lawsuits against three industries that were eventually found to be selling products damaging to human heath and the environment: lead paint, asbestos, and fossil fuels. These industries are similar in that some companies tried to hide or distort information showing their products were harmful. Common law claims were eventually filed to hold the corporations accountable and compensate the injured. This paper considers the important role the lawsuits played in helping establish some accountability for the industries while also noting the limitations of the lawsuits. It will be argued that the lawsuits helped create pressure for government regulation of the industries' products but were less successful at securing compensation for the injured. Thus, the common law claims strengthened and supported administrative regulation and the adoption of industry alternatives more than they provided a means of legal redress.

Malignant Pleural Mesothelioma: Accuracy of CT Against Immunohistochemical Test Among the Mexican Population

BACKGROUND AND AIMS

Malignant pleural mesothelioma (MPM) is associated with occupational and environmental exposure to asbestos. The incidence is expected to increase as the use of asbestos is not prohibited in many countries, such as in Mexico. We undertook this study to determine sensitivity, specificity, predictive values and likelihood ratios of computed tomography (CT) in a sample from Mexican population with suspected MPM and other pleuropulmonary diseases.

METHODS

CT films of 38 patients suspected of having MPM were analyzed. A single observer was blinded to MPM diagnoses. The frequencies of ten CT findings were identified. A cut-off point of ≥5 CT findings was established to determine high MPM probability. Sensitivity, specificity, predictive values and likelihood ratio of the CT against biopsy using immunohistochemical testing (IHC) for MPM were calculated.

RESULTS

Of the 38 patients, 31 had MPM and seven had lung adenocarcinoma. The five key findings were mediastinal pleural thickening 96.7% (n = 30), nodular pleural thickening 93.3% (n = 29), pleural mass 83.9% (n = 26), diminished lung 70.9% (n = 22) and contracted hemithorax 70.9% (n = 22). Sensitivity 96.8% (83.2-99.4), specificity 85.7% (42.2-97.6), positive likelihood ratio 6.7 (1.1-41.6), and negative likelihood ratio of 0.04 (0.01-0.2) were reported.

CONCLUSIONS

Sensitivity and specificity in this study was greater than previously reported, 96.8% and 85.7 vs. 93.2 and 65.6%, respectively. CT is an easily accessible and useful tool that should be incorporated into the medical education of general physicians to improve MPM diagnosis of suspected cases.

Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers

In 2011, SCOEL classified RCF as a secondary genotoxic carcinogen and supported a practical threshold. Inflammation was considered the predominant manifestation of RCF toxicity. Intrapleural and intraperitoneal implantation induced mesotheliomas and sarcomas in laboratory animals. Chronic nose-only inhalation bioassays indicated that RCF exposure in rats increased the incidence of lung cancer and similar exposures resulted in mesothelioma in hamsters, but these studies may have been compromised by overload. Epidemiological studies in the US and Europe showed an association between exposure and prevalence of respiratory symptoms and pleural plaques, but no interstitial fibrosis, mesotheliomas, or increased numbers of lung tumors were observed. As the latency of asbestos induced mesotheliomas can be up to 50 years, the relationship between RCF exposure and respiratory malignances has not been fully determined. Nonetheless, it is possible to offer useful perspectives. RCF and rock wool have similar airborne fiber dimensions and biopersistence. Therefore, it is likely that these fibers have similar toxicology. Traditional rock wool has been the subject of numerous cohort and case control studies. For rock wool, IARC (2002) concluded that the epidemiological studies did not provide evidence of carcinogenicity. Based on analogies with rock wool (read across), it is reasonable to believe that increases in lung cancer or any mesotheliomas are unlikely to be found in the RCF-exposed cohort. RCF producers have developed a product stewardship program to measure and control fiber concentrations and to further understand the health status of their workers.

Impact of a nursing education program about caring for patients in Japan with malignant pleural mesothelioma on nurses' knowledge, difficulties and attitude: a randomized control trial

PURPOSE

In Japan nursing care lags behind the growing population of patients with malignant pleural mesothelioma. This study evaluated an educational program for nurses about caring for patients with malignant pleural mesothelioma in Japan.

METHOD

In this randomized controlled study relative to care for malignant pleural mesothelioma, Knowledge, Difficulties and Attitude were measured at baseline, at post-test and at follow-up one month later. The two-day program with a half-day follow-up program included lectures, group work, role-playing and group discussion. 188 participants were randomly assigned to the intervention group (program, n=96) and control group (n=92; self-study by a similar content handbook). At baseline the groups showed no statistical differences in Knowledge (p=0.921), Difficulty (p=0.458) and Attitude (p=0.922). Completing the study were 177 participants yielding 88 in the intervention group and 89 in the control group. Human rights and privacy of participants were protected.

RESULTS

The Knowledge score was significantly higher in the intervention post-test (t=14.03, p=0.000) and follow-up test (t=8.98, p=0.000). Difficulty score was significantly lower in the intervention at post-test (t=-3.41, p=0.001) and follow-up test (t=-3.70, p=0.000). The Attitude score was significantly higher in the intervention post-test (t=7.11, p=0.000) and follow-up test (t=4.54, p=0.000). The two-way analysis of variance with repeated measures on time showed an interaction between time and group; the subsequent simple main effect test found significant differences (p=0.000-0.001) between groups for after-program and at follow-up and a significant difference (p=0.000) in time only within the intervention group.

CONCLUSION

The educational program was effective in improving the nurses' knowledge and attitude toward malignant pleural mesothelioma care and decreasing the difficulty in MPM care, therefore this program has potential for nurses' in-service education throughout Japan.

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.

Malignant mesothelioma after household exposure to asbestos

Malignant mesothelioma (MM) is an aggressive cancer that has been closely linked to asbestos exposure. Initially recognized as an occupational cancer in male workers, MM was later found to occur in their family members as well. We report the case of an 89-year-old female who presented with abdominal distention, pain, and findings consistent with malignant ascites. Family history was significant for fatal mesothelioma in her husband of 40 years, who was a worker at a tile factory. The diagnosis of MM was confirmed on pathologic examination of the omental core biopsy.

Pleural cancer mortality in Spain: time-trends and updating of predictions up to 2020

BACKGROUND

A total of 2,514,346 metric tons (Mt) of asbestos were imported into Spain from 1906 until the ban on asbestos in 2002. Our objective was to study pleural cancer mortality trends as an indicator of mesothelioma mortality and update mortality predictions for the periods 2011-2015 and 2016-2020 in Spain.

METHODS

Log-linear Poisson models were fitted to study the effect of age, period of death and birth cohort (APC) on mortality trends. Change points in cohort- and period-effect curvatures were assessed using segmented regression. Fractional power-link APC models were used to predict mortality until 2020. In addition, an alternative model based on national asbestos consumption figures was also used to perform long-term predictions.

RESULTS

Pleural cancer deaths increased across the study period, rising from 491 in 1976-1980 to 1,249 in 2006-2010. Predictions for the five-year period 2016-2020 indicated a total of 1,319 pleural cancer deaths (264 deaths/year). Forecasts up to 2020 indicated that this increase would continue, though the age-adjusted rates showed a levelling-off in male mortality from 2001 to 2005, corresponding to the lower risk in post-1960 generations. Among women, rates were lower and the mortality trend was also different, indicating that occupational exposure was possibly the single factor having most influence on pleural cancer mortality.

CONCLUSION

The cancer mortality-related consequences of human exposure to asbestos are set to persist and remain in evidence until the last surviving members of the exposed cohorts have disappeared. It can thus be assumed that occupationally-related deaths due to pleural mesothelioma will continue to occur in Spain until at least 2040.

Gemcitabine and vinorelbine as second-line or beyond treatment in patients with malignant pleural mesothelioma pretreated with platinum plus pemetrexed chemotherapy

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm that responds poorly to chemotherapy. Although treatment with pemetrexed in combination with cisplatin serves as first-line chemotherapy for MPM, the optimal second-line and beyond therapy has not yet been fully examined.

METHODS

Between March 2008 and October 2011, 17 consecutive Japanese patients pretreated with at least one regimen of platinum plus pemetrexed chemotherapy received gemcitabine and vinorelbine. Responses, survival time, and toxicity were retrospectively evaluated.

RESULTS

Response [partial response (PR) + complete response (CR)] and disease control [stable disease (SD) + PR + CR] rates were 18 and 82 %, respectively. The median progression-free survival (PFS) after combination chemotherapy was 6.0 months, whereas the median overall survival (OS) was 11.2 months. Grade 3 or 4 neutropenia and anemia were observed in 41 and 29 % of patients, respectively, and one patient experienced febrile neutropenia. Grade 3 or 4 nonhematologic toxicities included constipation (6 %) and phlebitis (6 %).

CONCLUSION

Combination chemotherapy using gemcitabine with vinorelbine was shown to have moderate activity in Japanese MPM patients pretreated with platinum plus pemetrexed chemotherapy. A further multicenter phase II trial is warranted to confirm the efficacy and safety of this combination treatment.

Malignant Mesothelioma Mortality in the United States, 1999–2001

Malignant mesothelioma is strongly associated with asbestos exposure. This paper describes demographic, geographic, and occupational distributions of mesothelioma mortality in the United States, 1999-2001. The data (n = 7,524) were obtained from the National Center for Health Statistics multiple-cause-of-death records. Mortality rates (per million per year) were age-adjusted to the 2000 U.S. standard population, and proportionate mortality ratios (PMRs) were calculated by occupation and industry, and adjusted for age, sex, and race. The overall age-adjusted mortality rate was 11.52, with males (22.34) showing a sixfold higher rate than females (3.94). Geographic distribution of mesothelioma mortality is predominantly coastal. Occupations with significantly elevated PMRs included plumbers/pipefitters and mechanical engineers. Industries with significantly elevated PMRs included ship and boat building and repairing, and industrial and miscellaneous chemicals. These surveillance findings can be useful in generating hypotheses and developing strategies to prevent mesothelioma.

Malignant pleural mesothelioma: incidence, etiology, diagnosis, treatment, and occupational health

BACKGROUND

The incidence of malignant mesothelioma in Germany is about 20 cases per million persons per year. Its association with asbestos exposure, usually occupational, has been unequivocally demonstrated. Even though the industrial use of asbestos was forbidden many years ago, new cases of mesothelioma continue to appear because of the long latency of the disease (median, 50 years). Its diagnosis and treatment still present a major challenge for ambulatory and in-hospital care and will do so for years to come.

METHODS

This article is based on a selective review of the literature, along with data from the German Mesothelioma Register.

RESULTS

1397 people died of mesothelioma in Germany in 2010. A plateau in the incidence of the disease is predicted between 2015 and 2030. Most mesotheliomas arise from the pleura. The histological subtype and the Karnofsky score are the main prognostic factors. Only limited data are now available to guide treatment with a combination of the available methods (chemotherapy, surgery, radiotherapy). The prognosis is still poor, with a median survival time of only 12 months. Symptom control and the preservation of the patient's quality of life are the main aspects of care for patients with mesothelioma.

CONCLUSION

The incidence of mesothelioma is not expected to drop in the next few years. The available treatments are chemotherapy, surgery, and radiotherapy. Specialized treatment centers now increasingly provide multimodal therapy for treatment of mesothelioma.

Molecular pathogenesis of malignant mesothelioma

Malignant mesothelioma is a rare, highly aggressive cancer arising from mesothelial cells that line the pleural cavities. Approximately 80% of mesothelioma cases can be directly attributed to asbestos exposure. Additional suspected causes or co-carcinogens include other mineral fibres, simian virus 40 (SV40) and radiation. A mesothelioma epidemic in Turkey has demonstrated a probable genetic predisposition to mineral fibre carcinogenesis and studies of human tissues and animal models of mesothelioma have demonstrated genetic and epigenetic events that contribute to the multistep process of mineral fibre carcinogenesis. Several growth factors and their receptors have a significant role in the oncogenesis, progression and resistance to therapy of mesothelioma. Epidermal growth factor (EGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and insulin-like growth factor (IGF) have been shown as targets for therapy based on promising preclinical data. However, clinical trials of tyrosine kinase inhibitors in mesothelioma have been disappointing. Bcl-XL is an important antiapoptotic member of the Bcl-2 family and is overexpressed in several solid tumours, including mesothelioma. Reduction of Bcl-XL expression in mesothelioma induces apoptosis and engenders sensitisation to cytotoxic chemotherapeutic agents. Pharmacological inhibitors of antiapoptotic Bcl-2 family members continue to undergo refinement and have shown promise in mesothelioma.

Preclinical studies identify novel targeted pharmacological strategies for treatment of human malignant pleural mesothelioma

The incidence of human malignant pleural mesothelioma (hMPM) is still increasing worldwide. hMPM prognosis is poor even if the median survival time has been slightly improved after the introduction of the up-to-date chemotherapy. Nevertheless, large phase II/III trials support the combination of platinum derivatives and pemetrexed or raltitrexed, as preferred first-line schedule. Better understanding of the molecular machinery of hMPM will lead to the design and synthesis of novel compounds targeted against pathways identified as crucial for hMPM cell proliferation and spreading. Among them, several receptors tyrosine kinase show altered activity in subsets of hMPM. This observation suggests that these kinases might represent novel therapeutic targets in this chemotherapy-resistant disease. Over these foundations, several promising studies are ongoing at preclinical level and novel molecules are currently under evaluation as well. Yet, established tumour cell lines, used for decades to investigate the efficacy of anticancer agents, although still the main source of drug efficacy studies, after long-term cultures tend to biologically diverge from the original tumour, limiting the predictive potential of in vivo efficacy. Cancer stem cells (CSCs), a subpopulation of malignant cells capable of self-renewal and multilineage differentiation, are believed to play an essential role in cancer initiation, growth, metastasization and relapse, being responsible of chemo- and radiotherapy refractoriness. According to the current carcinogenesis theory, CSCs represent the tumour-initiating cell (TIC) fraction, the only clonogenic subpopulation able to originate a tumour mass. Consequently, the recently described isolation of TICs from hMPM, the proposed main pharmacological target for novel antitumoural drugs, may contribute to better dissect the biology and multidrug resistance pathways controlling hMPM growth.

Potential health hazards associated with exposures to asbestos-containing drywall accessory products: A state-of-the-science assessment

Until the late 1970s, chrysotile asbestos was an ingredient in most industrial and consumer drywall accessory products manufactured in the US. In 1977, the Consumer Product Safety Commission (CPSC) issued a ban of consumer patching compounds containing "respirable, free-form asbestos" based on their prediction of exceptionally high rates of asbestos-related diseases among individuals using patching compounds for as little as a few days. Although hundreds of thousands of workers and homeowners handling these products may have experienced exposure to asbestos prior to the ban, there has been no systematic effort to summarize and interpret the information relevant to the potential health effects of such exposures. In this analysis, we provide a comprehensive review and analysis of the scientific studies assessing fiber type and dimension, toxicological and epidemiological endpoints, and airborne fiber concentrations associated with joint compound use. We conclude that: 1) asbestos in drywall accessory products was primarily short fiber (< 5 µm) chrysotile, 2) asbestos in inhaled joint compound particulate is probably not biopersistent in the lung, 3) estimated cumulative chrysotile exposures experienced by workers and homeowners are below levels known to be associated with respiratory disease, and 4) mortality studies of drywall installers have not demonstrated a significantly increased incidence of death attributable to any asbestos-related disease. Consequently, contrary to the predictions of the CPSC, the current weight of evidence does not indicate any clear health risks associated with the use of asbestos-containing drywall accessory products. We also describe information gaps and suggest possible areas of future research.

Case-control study of pleural mesothelioma in workers with social security in Mexico

BACKGROUND

Environmental and occupational exposure to asbestos in Mexico in the past has been a cause of deaths and health damages. Its magnitude is unknown to date. Our objective was to identify the proportion of cases of malignant pleural mesothelioma (MPM) that can be attributed to and occupational exposure to asbestos.

METHODS

We carried out a case-control study of MPM in 472 workers insured by the Mexican Institute of Social Security, all Valley of Mexico residents, with 119 incident cases and 353 controls. Cases were histologically confirmed. Participants were questioned concerning their occupational history and sociodemographic data. Assignment to one of the four exposures was performed qualitatively by an expert hygienist. Odds ratios (ORs) and attributable risks (ARs) were calculated using a non-conditional logistic regression model.

RESULTS

A total of 80.6% of cases and 31.5% of controls had occupational exposure to asbestos. ORs were adjusted for age and gender and by exposure category, and exhibited an increase with probability of exposure as follows: 3.7(95% CI 1.3-10.4) for the likely category and 14.3(95% CI 8-26) for the certain category; AR in the group occupationally exposed to asbestos was 83.2%, and the population AR was 44%.

CONCLUSIONS

Our results show that the relationship between industrial uses of all forms of asbestos is generating an increase in mesothelioma-related diseases and deaths among Mexican workers. As a public health policy, Mexico should prohibit the use of asbestos in all production processes with the aim of controlling the epidemic and preventing the occurrence of new cases of MPM.

Mesothelioma: path to multimodality treatment

Multimodality treatment of malignant pleural mesothelioma (MPM) with surgery, radiation therapy, and adjuvant or neoadjuvant chemotherapy is the sole path to extended survival for select patients with favorable prognostic factors. No single-modality approach has produced equivalent results. Much effort has been expended since first recognition of this insidious pleural cancer to elucidate the underlying cause and optimal treatment strategy. Despite recent breakthroughs, the principal barrier to achieving a cure rests with the propensity for disease recurrence in the ipsilateral hemithorax. Despite these limitations, however, the results hold promise for improved survival with further refinement in patient selection and targeted therapy. Other approaches to multimodality treatment have capitalized on an array of innovative technologies in search of the silver bullet strategy that will ultimately undermine the biological behavior demonstrated by MPM. These range from the use of different means of radiation delivery, biological agents, virally mediated gene therapy, photodynamic therapy, and immunotherapy. Additionally, studies using gene ratios will yield more accurate means by which to diagnose, distinguish prognosticators, and more selectively assign patients to aggressive treatments. In light of the current worldwide epidemic, the lessons learned over the past several decades serve as a humbling reminder of the treatment barriers that remain.