[Mesothelioma]

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

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

Substance GP-2250 as a New Therapeutic Agent for Malignant Peritoneal Mesothelioma—A 3-D In Vitro Study

Malignant peritoneal mesothelioma is a rare tumor entity. Although cytoreductive surgery and hyperthermic intraperitoneal chemotherapy have increased overall survival, its prognosis remains poor. Established chemotherapeutics include mitomycin C (MMC) and cisplatin (CP), both characterized by severe side effects. GP-2250 is a novel antineoplastic agent, currently under clinical investigation. This in vitro study aims to investigate effects of GP-2250 including combinations with CP and MMC on malignant mesothelioma. JL-1 and MSTO-211H mesothelioma cell lines were treated with increasing doses of GP-2250, CP, MMC and combination therapies of GP-2250 + CP/MMC. Microscopic effects were documented, and a flow-cytometric apoptosis/necrosis assay was performed. Synergistic and antagonistic effects were analyzed by computing the combination index by Chou-Talalay. GP-2250 showed an antiadhesive effect on JL-1 and MSTO-211H spheroids. It had a dose-dependent cytotoxic effect on both monolayer and spheroid cultured cells, inducing apoptosis and necrosis. Combination treatments of GP-2250 with MMC and CP led to significant reductions of the effective doses of CP/MMC. Synergistic and additive effects were observed. GP-2250 showed promising antineoplastic effects on malignant mesothelioma cells in vitro especially in combination with CP/MMC. This forms the basis for further in vivo and clinical investigations in order to broaden treatment options.

Asbestos danger in central Europe is not yet over - the situation in the Czech Republic

OBJECTIVES

In the Czech Republic, asbestos has been classified as a known human carcinogen since 1984. The use of asbestos-containing products was limited to scenarios where the use of other materials was not possible. Since 1997, the manufacture of asbestos materials has been forbidden, and in 1999, the import, manufacture and distribution of all types of asbestos fibres was legally banned by Act No. 157/1998 Coll. Although the use of asbestos is forbidden, the risk of exposure still exists given the ongoing demolition and reconstruction of buildings in which asbestos has been used. In addition, a novel risk has arisen through the quarrying of asbestos-containing aggregates and their subsequent use. The aim of this paper was to describe and evaluate asbestos in terms of history, legislation, current risk of occupational exposure and its health consequences in the Czech Republic over the last three decades.

METHODS

This retrospective descriptive study used the collected data on occupational exposure and occupational diseases. The counts of workers occupationally exposed to asbestos were obtained from the Registry of Work Categorization; the numbers and structure of occupational diseases caused by asbestos were taken from the Czech National Registry of Occupational Diseases. Data on the total number of mesothelioma cases recorded in the Czech National Cancer Registry was provided by the Institute of Health Information and Statistics of the Czech Republic.

RESULTS

A total of 13,112 subjects were registered as occupationally exposed to asbestos during the period 2001-2020. A total of 687 cases of asbestos-related occupational diseases were reported in the period 1991-2020 in the Czech Republic, comprising 178 cases of asbestosis, 250 cases of pleural hyalinosis, 168 cases of pleural or peritoneal mesothelioma, 90 cases of lung cancer, and one case of laryngeal cancer. The data from the Czech National Cancer Registry, available for a shorter period (1991-2018), reveal 1,389 cases of mesothelioma, of which only ~11% were recognised as occupational, despite the fact that the occupational causality of mesotheliomas is estimated to be up to 90% of mesotheliomas. Moreover, the latency of mesotheliomas since the last occupational exposure reached up to 50 years and this trend is still slightly increasing, unlike asbestosis, where a high cumulative dose of inhaled asbestos is needed. The real proportion of occupational lung cancers may obviously be even higher, especially in smokers, where occupational causes including asbestos are not suspected by most physicians.

CONCLUSION

Czech data on asbestos-related occupational diseases, especially cancers, are grossly underestimated, which is most apparent through the low proportion of mesotheliomas diagnosed as occupational. Asbestos materials in older buildings remained in situ and may represent a danger during reconstruction works. The current source of exposure appears to be quarrying of asbestos-containing aggregate and its subsequent use. Awareness of the professional community is therefore crucial, not only for the possibility of compensating those affected, but also for the early detection of the diseases through the dispensary of exposed persons.

Primary malignant peritoneal mesothelioma mimicking tuberculous peritonitis: A case report

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is a rare malignancy arising in mesothelial cells in the peritoneum. It can be mistaken for many other diseases, such as peritoneal carcinomatosis and tuberculous peritonitis (TBP), because its clinical manifestations are often nonspecific. Therefore, the diagnosis of MPM is often challenging and delayed.

CASE SUMMARY

A 42-year-old man was referred to our hospital with lower abdominal pain for 1 wk and ascites observed under abdominal sonography. His laboratory findings revealed an isolated elevated tumor marker of carcinoma antigen 125 (167.4 U/mL; normal, < 35 U/mL), and contrast enhanced computed tomography showed peritoneal thickening. Thus, differential diagnoses of TBP, carcinomatosis of an unknown nature, and primary peritoneal malignancy were considered. After both esophagogastroduodenoscopy and colonoscopy produced negative findings, laparoscopic intervention was performed. The histopathological results revealed mesothelioma invasion into soft tissue composed of a papillary, tubular, single-cell arrangement of epithelioid cells. In addition, immunohistochemical staining was positive for mesothelioma markers and negative for adenocarcinoma markers. Based on the above findings, TBP was excluded, and the patient was diagnosed with MPM.

CONCLUSION

It is important to distinguish MPM from TBP because they have similar symptoms and blood test findings.

Where are the landfilled zones? Use of historical geographic information and local spatial knowledge to determine the location of underground asbestos contamination in Sibaté (Colombia)

INTRODUCTION

Sibaté is a municipality located in the central region of Colombia, where the first asbestos-cement facility of the country has been in operation since 1942. Both a malignant pleural mesothelioma cluster and landfilled zones with the presence of an underground friable asbestos layer have been identified in Sibaté. There is still limited knowledge regarding the history of the construction of landfilled zones, and what kinds of materials were deposited. The current study aims to improve our understanding of the history and characteristics of the landfilled zones present in Sibaté.

METHODS

Two participatory workshops with inhabitants of Sibaté were conducted to determine when the landfilled zones were built and their location. Information collected in participatory workshops was crossed with both topographic maps and aerial photographs, giving special attention to zones within the urban area of the municipality that in the past were inundated with water from El Muña Reservoir. An opportunistic soil sampling campaign was conducted in suspected landfilled zones that had not been previously sampled, during the replacement of pipelines of the drainage system ordered by the municipality.

RESULTS

The analysis of historical topographic maps, combined with the interpretation of aerial photographs, confirmed the disposal of residues in areas that were previously inundated with water from El Muña Reservoir, creating landfilled zones in the urban area of Sibaté. On top of these landfilled zones, a football stadium and a football field with an athletic track were built. The location of landfilled zones identified using geographic analysis was similar to the location identified analyzing maps constructed by inhabitants of Sibaté in participatory workshops. The four soil samples collected during an opportunistic sampling campaign confirmed the presence in new locations of the underground friable asbestos layer discovered in previous studies.

DISCUSSION

Based on the extension of the landfilled zones, the presence of friable asbestos in these areas, and the close proximity to a school and residential dwellings, there could have been major dispersion events of asbestos fibers in the urban area of Sibaté during the disposal of residue materials and the construction of the landfilled zones. Thus, important asbestos exposures may have occurred among residents of Sibaté, which is aggravated by the fact that during those years, more than 50% of the population of Sibaté was 25 years old or younger. Although the results of the current study improved our understanding of the processes and chronology associated with the landfilled zones, the uncertainty regarding their exact location remains significant. It is important to continue investigating the adverse health effects resulting from this potential asbestos exposure source.

Reactive mesothelial hyperplasia mimicking mesothelioma in an African green monkey (Chlorocebus aethiops)

A spontaneous reactive mesothelial hyperplasia occurred in a female, 15.7-year-old African green monkey (grivet; Chlorocebus aethiops). At necropsy, massive effusions were found in the abdomen, the thorax, and the pericardium. Additionally, multiple small, beige-gray nodules were detected on the serosal surfaces of the abdominal organs. Histopathologically, the mesothelial cells resembled the epithelioid subtype of a mesothelioma, but no infiltrative or invasive growth could be demonstrated. The mesothelial cells on the thoracis, liver, and intestinal serosa were accompanied by chronic serositis. Mesothelial cells expressed cytokeratin, vimentin, calretinin, desmin, Wilms Tumor 1 (WT-1) protein, and epithelial membrane antigen (EMA). Cells were negative for carcinoembryonic antigen (CEA), cluster of differentiation 15 (CD15), and podoplanin. Ultrastructurally, cells revealed a moderate amount of microvilli of medium length, perinuclear tonofilament bundles, and long desmosomes. In fluorescence in situ hybridization (FISH) for the detection of characteristic gene loss (p16; CDKN2A), NF2, and MTAP, no deletions were detected. No asbestos fibers and no presence of Simian virus 40 antigen (SV40) could be demonstrated.