Malignant pleural mesothelioma due to environmental mineral fiber exposure in Turkey. Analysis of 135 cases

Mesothelioma Due to Workplace Exposure: A Comprehensive Bibliometric Analysis of Current Situation and Future Trends

Background: This article provides an overview of the current status and research progress of mesothelioma. Methods: A total of 2638 documents published from 1 January 2004 to 30 November 2022 were retrieved from the Web of Science Core Collection and analyzed via Microsoft Office Excel 2019, VOSviewer 1.6.18, and Tableau 2022.2. Results: There was an obvious increase in the number of publications regarding mesothelioma in the last 18 years, with the United States dominating the research field with 715 publications and 23,882 citations, while the University of Turin contributed the most (118). Occupational & Environmental Medicine was the most popular journal (80), with Corrado Magnani being the most prolific author (52) and Michele Carbone obtaining the most citations (4472). "Oncology" and "Health Science of Environment & Occupation" were the two main subjects, while the keywords "asbestos", "lung cancer", "gene expression", "apoptosis", "survival", and "cisplatin" were the most popular. Conclusions: The containment of mesothelioma calls for more participation from low- and middle-income countries, and further attention needs to be paid to clinical research.

Respirable inorganic fibers dispersed in air and settled in human lung samples: Assessment of their nature, source, and concentration in a NW Italy large city

The present investigation represents a new approach useful to evaluate the general population risk correlated with environmental exposure to air dispersed inorganic fibers. The used method is based on the evaluation of the respirable inorganic fibers both air dispersed in a big city and contained in lungs of the general population following their respiration. Moreover, these data allow to identify the sources of dispersion (anthropogenic or natural) in air of the inorganic fibers and therefore to apply strategies to improve air quality. To describe this approach, we investigated air samples from a big city in NW Italy and lung inorganic burden of people here lived. This paper reports the data of the airborne inorganic fibers detected in two sampling campaign (2014 and 2016), in 24 districts of Torino (Piemonte - NW Italy), and in some autoptic lungs of general population lived here. The airborne fibers (collected on mixed-cellulose esters membrane) were characterized by SEMEDS. The identified inorganic fiber species were assigned to 5 classes, one of these including 2 types of asbestos. These last are grouped as tremolite/actinolite asbestos. They are dispersed from natural sources (i.e. certain kinds of rocks outcropping in the city surrounding areas). In no-one of the 24 districts of Torino their concentration highlighted a situation of asbestos pollution in place. A correlation with inorganic fibers (collected on mixed-cellulose esters membrane and characterized by SEM-EDS) detected in lung tissue samples of 10 subjects lived in Torino all their life and without professional exposure to asbestos were attempted. The only types of fibers identified as asbestos are tremolite/actinolite asbestos, and they match those detected in air sampling. The number of fibers per 1 g of tissue dry weight is lower than the quantities reported as indicative of significant asbestos exposure. We observed interesting gender differences.

A review of the cohorts with environmental and occupational mineral fiber exposure

The aim of the study was to examine factors associated with Malignant Mesothelioma (MM) incidence rate of the groups with occupational asbestos and environmental asbestos or erionite exposure in rural area. In this ecological study, a total of 21 cohort datasets (8 environmental and 13 occupational) were evaluated. Data were analyzed using a multiple linear regression analysis model. In environmental cohorts, the risk of MM incidence was higher in women and people exposed to erionite. In this cohort, the incidence rate of MM increased as the median exposure time increased, while the incidence decreased as the median cumulative exposure dose increased. In occupational cohorts, the incidence rate of MM was positively correlated with the median cumulative exposure dose. The risk of mesothelioma was lower in those exposed to tremolite than others. Environmental asbestos exposure is as important as occupational exposure to develop MM, and it has its own unique exposure features on the risk of MM.

Turkey National Mesothelioma Surveillance and Environmental Asbestos Exposure Control Program

Malignant mesothelioma (MM) is an important health problem due to ongoing asbestos exposure. Environmental asbestos exposure leads to a high risk of MM in Turkey. The Turkish Mesothelioma Working Group and the Turkish Public Health Institute designed and performed the Turkey National Mesothelioma Surveillance and Environmental Asbestos Exposure Control Program (TUNMES-EAECP). The aim of this study was to analyze the results of the TUNMES-EAECP. Patients diagnosed with MM (code C45.0-C45.9) between 2008 and 2012 were identified. The "from case to the field" method was used to determine the villages with current or previous asbestos exposure. Special public health teams took soil samples from these villages, which were then examined using an X-ray diffractometer. Direct Standardized Average Annual Mesothelioma Incidence Rate (AMIR) and relative risk (RR) of MM were calculated. Finally, a projection on the incidence of MM between 2013 and 2033 was made. The number of confirmed MM cases was 5617 with a male to female ratio of 1.36. Mean age was 61.7 ± 13.4 (20-96) years. The median survival was eight (95% CI 7.6-8.4) months. Asbestos exposure continues in 379 villages, with 158,068 people still living in high risk areas. The standardized AMIR was 2.33/100,000 per year. The risk of MM was higher in males, in both sexes over the age of 40, in asbestos-containing provinces, and in those where the TUNMES was organized. Among the population with continuing asbestos exposure in rural areas, the number of MM cases between 2013 and 2033 was estimated as 2511. As such, the incidence of MM in Turkey is as high as in industrialized countries. Asbestos exposure in rural areas continues to be a serious problem in Turkey, which obviates the necessity for effective preventive measures.

Asbestos knowledge and awareness level in central part of Anatolia

Background Asbestos-contaminated soil has been used by people for many years in the rural part of Anatolia. However, there is no program to control usage of asbestos in this region. Objective To determine the knowledge and awareness level about asbestos in a region where asbestos-related diseases are endemic due to environmental exposure to asbestos in the rural setting. Methods This study included 760 participants, recruited using non-probability sampling, who were classified into four groups according to residence and asbestos exposure type (urban, rural; asbestos-exposed, asbestos-unexposed). Asbestos knowledge and awareness was measured via the Asbestos Knowledge and Awareness Questionnaire (AKAQ). The cut-off value of questionnaire was determined by the K-means cluster analysis for sufficient and insufficient knowledge and awareness level. A multiple logistic regression analysis was performed to determine independent factors affecting sufficient knowledge and awareness of participants about asbestos. Results The median and mean score of the AKAQ in study group were 30 and 33.9, respectively. The urban asbestos-exposed group had a higher score than the urban asbestos-unexposed and both rural groups (p < 0.001). Factors affecting asbestos knowledge and awareness were education status (p = 0.035), asbestos exposure (p = 0.003) and living in the rural area (p = 0.005). Sufficient knowledge and awareness (score > 45) was higher among participants who had graduated from university and had asbestos exposure. Insufficient knowledge and awareness level was higher among participants living in rural areas. Conclusion In this region of Anatolia, knowledge and awareness level of asbestos was low among people at risk for environmental asbestos exposure. People should be aware of asbestos and its hazards by a well-designed training program and be monitored for asbestos-related diseases.

The Cappadocia mesothelioma epidemic: its influence in Turkey and abroad

The epidemic of mesothelioma in Cappadocia, Turkey, is unprecedented in medical history. In three Cappadocian villages, Karain, Tuzkoy and "old" Sarihidir, about 50% of all deaths (including neonatal deaths and traffic fatalities) have been caused by mesothelioma. No other epidemic in medical history has caused such a high incidence of death. This is even more unusual when considering that (I) epidemics are caused by infectious agents, not cancer, and (II) mesothelioma is a rare cancer. World-wide mesothelioma incidence varies between 1/10⁶ in areas with no asbestos industry to about 10-30/10⁶ in areas with asbestos industry. This article reviews how the mesothelioma epidemic was discovered in Cappadocia by Dr. Baris (my mentor), how we initially linked the epidemic to erionite exposure, and later (with Dr. Carbone) to the interaction between genetic predisposition and environmental exposure. Our team's work had an important positive impact on the lives of those living in Cappadocia and also in many genetically predisposed families living around the world. I will discuss how the work that started in three remote Cappadocian villages led to the award of a NCI P01 grant to support our studies. Our studies proved that genetics modulates mineral fiber carcinogenesis and led to the discovery that carriers of germline BAP1 mutations have a very high risk of developing mesothelioma and other malignancies. A new, very active field of research developed following our discoveries to elucidate the mechanism by which BAP1 modulates mineral fiber carcinogenesis as well as to identify additional genes that when mutated increase the risk of mesothelioma and other environmentally related cancers. I am the only surviving member of this research team who saw all the phases of this research and I believe it is important to provide an accurate report, which hopefully will inspire others.

High-risk mesothelioma relation to meteorological and geological condition and distance from naturally occurring asbestos

OBJECTIVES

Very few studies have investigated the incidence and risk of malignant mesothelioma (MM) associated with distinct sources of asbestos exposure, especially exposure to naturally occurring asbestos (NOA).

METHODS

Subjects were MM, lung, and breast cancer patients who were diagnosed and followed in Diyarbakir Province between 2008 and 2013. The birthplaces of patients were displayed on a geologic map. Geological and meteorological effects on MM were analyzed by logistic regression.

RESULTS

A total of 180 MM, 368 breast, and 406 lung cancer patients were included. The median distance from birthplace to ophiolites was 6.26 km for MM, 31.06 km for lung, and 34.31 km for breast cancer (p < 0.001). The majority of MM cases were seen within 20 km from NOA areas. The MM incidence inside of NOA was 1059/100.000, and out of NOA was 397/100.000; this difference was significant (p = 0.014). The largest concentration of MM residential areas was within ± 30° (34 residential areas 36.6%) of the dominant wind direction. Most MM patients were found in or near the dominant wind direction, especially in the acute angle defined by the dominant wind direction. MM incidence was directly proportional to {[area of NOA (km(2))] * [cosine α of wind direction angle]} and was inversely proportional to the square of the distance (R = 0.291, p = 0.023).

CONCLUSIONS

MM was higher near NOA and in the downwind direction. MM incidence and risk were affected by geological and meteorological factors.

Clinical and prognostic features of erionite-induced malignant mesothelioma

This review analytically examines the published data for erionite-related malignant pleural mesothelioma (E-MPM) and any data to support a genetically predisposed mechanism to erionite fiber carcinogenesis. Adult patients of age ≥18 years with erionite-related pleural diseases and genetically predisposed mechanisms to erionite carcinogenesis were included, while exclusion criteria included asbestos- or tremolite-related pleural diseases. The search was limited to human studies though not limited to a specific timeframe. A total of 33 studies (31042 patients) including 22 retrospective studies, 6 prospective studies, and 5 case reports were reviewed. E-MPM developed in some subjects with high exposures to erionite, though not all. Chest CT was more reliable in detecting various pleural changes in E-MPM than chest X-ray, and pleural effusion was the most common finding in E-MPM cases, by both tests. Bronchoalveolar lavage remains a reliable and relatively less invasive technique. Chemotherapy with cisplatin and mitomycin can be administered either alone or following surgery. Erionite has been the culprit of numerous malignant mesothelioma cases in Europe and even in North America. Erionite has a higher degree of carcinogenicity with possible genetic transmission of erionite susceptibility in an autosomal dominant fashion. Therapeutic management for E-MPM remains very limited, and cure of the disease is extremely rare.

Malignant pleural mesothelioma: a single-center experience in Turkey

BACKGROUND

Malignant pleural mesothelioma is a rare lethal malignancy caused by asbestos exposure. It is more frequently seen in certain regions in Turkey. In this retrospective study, we aimed to analyse demographic, clinical, and pathological data and treatment-related features in 54 patients.

MATERIAL AND METHODS

The study included 54 patients diagnosed with malignant mesothelioma that were followed and treated.

RESULT

Of the 54 patients, 34 (55.6%) were male. The median age in men and women were 60.3 (38.2-77.2) and 65.8 (37.7-77.5) years, respectively. In 35 (64.8%), exposure to asbestosis was present. Epithelial type was found in 27 (50.0%), followed by mixed type in 7 (13.0%) patients, and in 20 (37.0%) patients the subtype could not be determined. The disease was staged as IV in 37 (68.5%) patients. In 28 patients (51.9%), it was right-sided and in 1 (1.9%) it was bilateral. The most frequent metastatic sites (in decreasing order) were lungs, mediastinum, diaphragm, liver, and thoracal wall. Of the 54 patients, 36 (66.6%) received 1st-line chemotherapy and 20 (37%) 2nd-line chemotherapy. Eighteen patients (33.3%) received radiotherapy; 11 (20.3%) with palliative intention and 7 (12.9%) with curative intention. Median overall survival (OS) was 12.03 months (95% CI 7.2-16.8). OS was not affected by sex (p=0.32), smoking history (p=0.51), alcohol consumption (p=0.36), family history (p=0.67), pleural effusion presence (p=0.80), operation (p=0.14), clinical stage (p=0.072), symptom at presentation (p=0.66), having mixed type histology (p=0.079), asbestos exposure (p=0.06), and type of 1st-line chemotherapy (p=0.161). On the contrary, it may be positively affected by good ECOG PS (0-1) (p<0.01), age below 65 (p=0.03), left-sided disease (p=0.01), receiving chemotherapy (p<0.01), having unilateral pleural effusion (p=0.018), and type of 2nd-line chemotherapy (p=0.025).

CONCLUSIONS

OS of our patients was better than that found in the literature, seeming to be positively affected by early stages, better ECOG PS, age below 65 years, left side involvement, and having second-line chemotherapy with cisplatin-gemcitabine or 3M. Overall treatment success seems to be comparable to what is currently expected.

Multipoint targeting of the PI3K/mTOR pathway in mesothelioma

BACKGROUND

Mesothelioma is a notoriously chemotherapy-resistant neoplasm, as is evident in the dismal overall survival for patients with those of asbestos-associated disease. We previously demonstrated co-activation of multiple receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR), MET, and AXL in mesothelioma cell lines, suggesting that these kinases could serve as novel therapeutic targets. Although clinical trials have not shown activity for EGFR inhibitors in mesothelioma, concurrent inhibition of various activated RTKs has pro-apoptotic and anti-proliferative effects in mesothelioma cell lines. Thus, we hypothesised that a coordinated network of multi-RTK activation contributes to mesothelioma tumorigenesis.

METHODS

Activation of PI3K/AKT/mTOR, Raf/MAPK, and co-activation of RTKs were evaluated in mesotheliomas. Effects of RTK and downstream inhibitors/shRNAs were assessed by measuring mesothelioma cell viability/growth, apoptosis, activation of signalling intermediates, expression of cell-cycle checkpoints, and cell-cycle alterations.

RESULTS

We demonstrate activation of the PI3K/AKT/p70S6K and RAF/MEK/MAPK pathways in mesothelioma, but not in non-neoplastic mesothelial cells. The AKT activation, but not MAPK activation, was dependent on coordinated activation of RTKs EGFR, MET, and AXL. In addition, PI3K/AKT/mTOR pathway inhibition recapitulated the anti-proliferative effects of concurrent inhibition of EGFR, MET, and AXL. Dual targeting of PI3K/mTOR by BEZ235 or a combination of RAD001 and AKT knockdown had a greater effect on mesothelioma proliferation and viability than inhibition of individual activated RTKs or downstream signalling intermediates. Inhibition of PI3K/AKT was also associated with MDM2-p53 cell-cycle regulation.

CONCLUSIONS

These findings show that PI3K/AKT/mTOR is a crucial survival pathway downstream of multiple activated RTKs in mesothelioma, underscoring that PI3K/mTOR is a compelling target for therapeutic intervention.

The assessment of the malignant mesothelioma cases and environmental asbestos exposure in Sivas province, Turkey

One of the most significant diseases related to environmental asbestos exposure is malignant mesothelioma (MM). Sivas province is located in the Central Anatolia where asbestos exposure is common. We aimed to study clinical, demographical and epidemiologic features of the patients with MM in Sivas, along with the history of asbestos exposure. In total, 219 patients with MM who were diagnosed in our hospital between 1993 and 2010 were retrospectively analyzed in terms of demographical and clinical features. Rock, soil and house plaster samples were taken from the habitats of those patients and were evaluated with optical microscopy and X-ray diffraction methods. The age of the patients ranged between 18 and 85 years. The male-to-female ratio was 1.4:1. Most of the patients confirmed an asbestos exposure history. The most frequent symptoms of the patients were chest pain (60 %) and dyspnea (50 %). The gap between the start of first symptoms and the diagnosis date was approximately 4 months in average. The plaster materials used in most of the houses were made up of mainly carbonate and silicate minerals and some chrysotile. Ophiolitic units contained fibrous minerals such as serpentine (clino + orthochrysotile) chiefly and pectolite, brucite, hydrotalcite and tremolite/actinolite in smaller amounts. MM is not primarily related to occupational asbestos exposure in our region, and hence, environmental asbestos exposure may be indicted. Yet, single or combined roles and/or interactions of other fibrous and non-fibrous minerals in the etiology of MM are not yet fully understood and remain to be investigated.

Is galectin-3 antibody a useful marker in the diagnosis of malignant pleural mesothelioma?

Malignant pleural mesothelioma (MPM) is a challenging diagnosis characterized by the absence of real specific diagnostic markers. Positivity with the galectin-3 antibody was assessed by a cytoplasmic expression in 17 MPM. Fourteen cases expressed the galectin-3 antibody. The three negative cases consisted of epithelioid, biphasic, and sarcomatoid MPM. The 14 positive cases consisted of epithelioid MPM in 12 cases, sarcomatoid MPM in one case, and biphasic MPM in one case. In spite of our inability to prove the real diagnostic value of the galectin-3 antibody, our findings make us wonder about the implication of this antibody in the carcinogenesis of MPM.

Desmoplastic malignant mesothelioma

Desmoplastic mesothelioma is a rare subtype of diffuse malignant mesothelioma. A 72-year-old woman from East Anatolia presented with chest pain. The images of body positron emission tomography revealed irregular, left pleural thickening involving mediastinal and diaphragmatic surfaces with hypermetabolic characterization. The diagnosis of desmoplastic malignant mesothelioma was confirmed by minithoracotomy and immunohistochemical staining with pan-cytokeratin, cytokeratin 5/6, calretinin, carcinoembryonic antigen, thyroid transcription factor-1, CD15, and HMB-45 on the biopsy specimen. This case is unique in terms of the reporting patient being from a nonendemic area for asbestos-related diseases and in terms of its rare histopathology.

Environmental asbestos exposure in rural Turkey and risk of lung cancer

The aim of this study was to determine the risk of lung cancer in a cohort of villagers with environmental asbestos exposure. The study was carried out as a field-based epidemiological study. Information from 3143 individuals in 15 asbestos exposed villages and 2175 individuals in 12 control villages was obtained. Asbestos fiber type to which villagers were exposed mainly was tremolite or tremolite, actinolite, chrysotile mixtures. The cumulative fiber count of the villagers during their lifespan ranged from 0.19 to 4.61 fiber-years/ml. The annual average incidence ratio of lung cancer was 135.21/100,000 persons/year in men and 47.28 in women in the asbestos exposed villages. For the control villages, this ratio was 60.15/100,000 person/year in men and 15.06 in women. Being a male, advanced age, smoking and asbestos exposure were established to increase the risk of lung cancer. Environmental asbestos exposure in rural area is a risk factor for lung cancer independent of smoking.

Evaluation of tremolite asbestos exposures associated with the use of commercial products

Tremolite is a noncommercial form of amphibole mineral that is present in some chrysotile, talc, and vermiculite deposits. Inhalation of asbestiform tremolite is suspected to have caused or contributed to an increased incidence of mesothelioma in certain mining settings; however, very little is known about the magnitude of tremolite exposure that occurred at these locations, and even less is known regarding tremolite exposures that might have occurred during consumer use of chrysotile, talc, and vermiculite containing products. The purpose of this analysis is to evaluate the exposure-response relationship for tremolite asbestos and mesothelioma in high exposure settings (mining) and to develop estimates of tremolite asbestos exposure for various product use scenarios. Our interpretation of the tremolite asbestos exposure metrics reported for the Thetford chrysotile mines and the Libby vermiculite deposits suggests a lowest-observed-adverse-effect level (LOAEL) for mesothelioma of 35-73 f/cc-year. Using measured and estimated airborne tremolite asbestos concentrations for simulated and actual product use, we conservatively estimated the following cumulative tremolite asbestos exposures: career auto mechanic: 0.028 f/cc-year; non-occupational use of joint compound: 0.0006 f/cc-year; non-occupational use of vermiculite-containing gardening products: 0.034 f/cc-year; home-owner removal of Zonolite insulation: 0.0002 f/cc-year. While the estimated consumer tremolite exposures are far below the tremolite LOAELs derived herein, this analysis examines only a few of the hundreds of chrysotile- and talc-containing products.

Clinical characteristics and treatment outcomes in 132 patients with malignant mesothelioma

Purpose:

Our objective is to scrutinize clinical, laboratory, radiological characteristics, treatment regimens, and treatment outcomes of malignant mesothelioma (MM) cases in our hospital.

Materials and Methods:

We investigated, retrospectively, the clinical characteristics and treatment outcomes of all 132 MM patients at Dicle University Hospital between January 2006 and April 2010.

Results:

A total of 82 (62.1%) patients were male, and 50 (37.9%) female. Median age was 56.0 years. Mean survival time was 9.6±6.9 months. Mean survival time of patients who had received best supportive care was 7.5 months, chemotherapy 10.4 months, and multimodality treatment regimen 12.6 months. Patients in the multimodality treatment group survived longer than did those in the other two groups (P=0.042). A total of 76 patients received chemotherapy, of whom 17 (22.3%) were administered Cisplatin/Carboplatin and Gemcitabine, 58 (76.4%) Cisplatin/Carboplatin and Pemetrexed, and one (1.3%) Cisplatin + Docetaxel. Complete and partial response to treatment in patients receiving Cisplatin/Carboplatin and Gemcitabine was found 47.1% and Cisplatin/Carboplatin and Pemetrexed was found 50.0% (P>0.05).

Conclusions:

MM related to asbestos exposure is seen frequently in Turkey. Patients present with the typical clinical features of dyspnea, weight loss, and chest pain. Survival analysis shows that patients receiving multimodality treatment may be better.

Asbestos-Related Lung Disease

Asbestos is a high-profile health hazard. This article examines the assessment asbestos-related malignant mesothelioma and lung cancer. The risk of developing these diseases increases in proportion to the cumulative dose. As persons with heavy occupational asbestos exposures are diminishing, the observed latent period for asbestos-related disease extends making the assessment of an individual's cumulative dose is now more problematic.

The health impact of nonoccupational exposure to asbestos: what do we know?

The objective of this study was to examine the epidemiological data that confirm the risks of pleural mesothelioma, lung cancer, and other respiratory damage associated with nonoccupational exposure to asbestos, in circumstances where exposure levels are usually lower than those found in the workplace: domestic and paraoccupational exposure to asbestos-containing material among people living with asbestos workers or near asbestos mines and manufacturing plants, environmental exposure from naturally occurring asbestos in soil, and nonoccupational exposure to asbestos-containing material in buildings. Studies concerning natural asbestos in the environment show that the exposure that begins at birth does not seem to affect the duration of the latency period, but the studies do not show whether early exposure increases susceptibility; they do not suggest that susceptibility differs according to sex. Solid evidence shows an increased risk of mesothelioma among people whose exposure comes from a paraoccupational or domestic source. The risk of mesothelioma associated with exposure as result of living near an industrial asbestos source (mines, mills, asbestos processing plants) is clearly confirmed. No solid epidemiological data currently justify any judgment about the health effects associated with passive exposure in buildings containing asbestos. Most of the studies on nonoccupational sources reported mainly amphibole exposure, but it cannot be ruled out that environmental exposure to chrysotile may also cause cancer. Nonoccupational exposure to asbestos may explain approximately 20% of the mesotheliomas in industrialized countries, but it is does not seem possible to estimate the number of lung cancers caused by these circumstances of exposure.

Mechanisms of pulmonary toxicity and medical applications of carbon nanotubes: Two faces of Janus?

Nanotechnology is an emerging science involving manipulation of materials at the nanometer scale. There are several exciting prospects for the application of engineered nanomaterials in medicine. However, concerns over adverse and unanticipated effects on human health have also been raised. In fact, the same properties that make engineered nanomaterials attractive from a technological and biomedical perspective could also make these novel materials harmful to human health and the environment. Carbon nanotubes are cylinders of one or several coaxial graphite layer(s) with a diameter in the order of nanometers, and serve as an instructive example of the Janus-like properties of nanomaterials. Numerous in vitro and in vivo studies have shown that carbon nanotubes and/or associated contaminants or catalytic materials that arise during the production process may induce oxidative stress and prominent pulmonary inflammation. Recent studies also suggest some similarities between the pathogenic properties of multi-walled carbon nanotubes and those of asbestos fibers. On the other hand, carbon nanotubes can be readily functionalized and several studies on the use of carbon nanotubes as versatile excipients for drug delivery and imaging of disease processes have been reported, suggesting that carbon nanotubes may have a place in the armamentarium for treatment and monitoring of cancer, infection, and other disease conditions. Nanomedicine is an emerging field that holds great promise; however, close attention to safety issues is required to ensure that the opportunities that carbon nanotubes and other engineered nanoparticles offer can be translated into feasible and safe constructs for the treatment of human disease.

[Erionite-induced pleural plaques. Exposition to urban pollution in a female Turkish migrant in Germany]

Erionite is a zeolite mineral of volcanic origin which contains no asbestos. It is found in different regions of the world, including southeast Turkey in ash and dust, from which it can cause inflammatory pleural plaques or malignant pleural mesothelioma (MPM). We report a female Turkish migrant exposed to urban pollution in her home country who decades later suffered from pleural plaques with a nonspecific chronic inflammatory disease. The differential diagnosis of inflammatory pleural plaques was assumed radiologically and confirmed by video-assisted thoracoscopic biopsy. Short-term clinical and radiologic control of the patient will be necessary because of the risk of MPM. For epidemiologic considerations discussed referring to current literature, a growing incidence of this type of disease in migrants from high-risk areas must be reckoned with in Germany, even without exposition to asbestos.

Select mortality and cancer incidence among residents in various U.S. communities that received asbestos-contaminated vermiculite ore from Libby, Montana

In response to the significantly elevated asbestosis mortality rates found in Libby, Montana, in 2000, this analysis evaluated whether other communities throughout the United States that received asbestos-contaminated vermiculite ore from Libby experienced similar excess rates of asbestos-related diseases. Standardized mortality ratios were calculated using state death certificates, and standardized incidence ratios were calculated using cancer registry records for populations living near facilities that processed or received Libby vermiculite. This analysis focused primarily on diseases that are directly associated with asbestos exposure (e.g., asbestosis; cancer of the peritoneum, retroperitoneum, and pleura, including mesothelioma; and mesothelioma). Lung cancer and cancers of the digestive system, also associated with asbestos exposure, were not included in the analysis because they have additional risk factors for which exposure information was not available. Data from 70 unique sites in 23 states were evaluated. No statistically significant excesses of asbestosis mortality similar to those in Libby were noted; however, 11 sites (plus a state with 6 pooled sites that were counted as 1 site) had excess rates of mesothelioma and cancer of the peritoneum, retroperitoneum, and pleura. Further investigation should be conducted at these sites with excess rates of mesothelioma and cancer of the peritoneum, retroperitoneum, and pleura by participating state health departments to determine whether exposure to Libby vermiculite might have been a contributing factor.

Recent discovery of an old disease: Malignant pleural mesothelioma in a village in south-east Turkey

BACKGROUND AND OBJECTIVE

Environmental asbestos exposure is reportedly common in some districts of Turkey. The aim of this study was to investigate the presence and effect of environmental asbestos exposure in a village in Gaziantep, Turkey, with reported cases of mesothelioma.

METHODS

All villagers > or =14 years old were subject to an interview rediagnosis and a detailed questionnaire. Chest microfilms were performed in all cases, and additional standard CXRs were obtained when necessary. Samples collected from the natural mantle, and whitewash from the houses were analysed for the presence of asbestos.

RESULTS

In total, 269 villagers took part in the study. The incidence of histopathologically diagnosed malignant pleural mesothelioma was 0.32% relative to the total village population in the year 2000. The verbal autopsy revealed eight possible cases of malignant pleural mesothelioma, all of whom had died within the past 12 years. Of these eight, there was a first-degree kinship between three, and additionally, these patients had a third-degree relationship with a biopsy proven case. Radiological evaluation showed pleural calcification and/or thickness in 3.3%, and pleural effusion in 0.4% of patients undergoing CXR. All houses in the village were constructed using adobe soil, and the interior whitewash was made from soil containing asbestos. Analysis of soil samples revealed tremolite and/or actinolyte asbestos.

CONCLUSION

The current findings suggest that environmental asbestos exposure continue to be a serious health concern in the Gaziantep region of Turkey.

Tumor suppressor gene alterations in patients with malignant mesothelioma due to environmental asbestos exposure in Turkey

BACKGROUND

Environmental asbestos exposure can cause the grave lung and pleura malignancies with a high mortality rate, and it is also associated with increased rate of other organ malignancies. Asbestos exposure can develop genotoxic effects and damage in the pleura and lungs.

OBJECTIVE

In this study, we aimed to determine tumor suppressor gene (TSG) loss in genomic DNA which was isolated from pleural fluid and blood samples of patients with Malignant Pleural Mesothelioma (MPM) due to environmental asbestos exposure.

DESIGN AND PATIENTS

Prospective study of period from 2001 to 2003 in 17 patients with MPM.

METHODS

A total of 12 chromosomal regions were researched by comparing genomic DNA samples isolated from blood and pleural effusion (using PCR, and polyacrylamide gel electrophoresis denaturizing), on 2 different chromosomes which have 9 different polymorphic determinants at 6q and 3 different polymorphic determinants at 9p using molecular genetic methods on 13 patients clinico-pathologically diagnosed MPM.

RESULTS

Loss of Heterozygosity (LOH) was determined at D6S275 in one patient, at D6S301 in another, at D6S474 in 2, at ARG1 in 2, at D6S1038 in 2 and at D6S1008 in 3 patients. In 7 (54%) of the 13 patients, we found LOH in at least one site. No LOH was determined at any informative loci in 6 patients. Of the 13 patients, no investigated markers were determined at 9p.

CONCLUSION

In this study, genomic DNA samples obtained from MPM patients with asbestos exposure revealed that they contained important genotoxic damage. We found no other study on this subject at molecular level in pleural effusion either in Turkey or in the Med-line literature. We believe that this study will provide important support for other research into molecular-genetic variations, both on this subject and other malignancies, and may also constitute a base for early diagnosis and gene therapy research in the future.

Computed tomography findings in 66 patients with malignant pleural mesothelioma due to environmental exposure to asbestos

We aimed to investigate the computed tomography (CT) findings of malignant pleural mesothelioma (MPM) caused by environmental asbestos exposure. We retrospectively reviewed CT scans of 66 patients, which were performed before any invasive procedure was done. Pleural effusion (80.3%), pleural thickening (77.2%), volume contraction (37.9%), involvement of mediastinal pleura (31.8%) and interlobar fissure (28.8%) were the most common CT findings of MPM. Although none of these findings are pathognomonic for MPM, they may provide valuable clues for the differential diagnosis, at least in patients with a history of asbestos exposure.

The epidemiology of asbestos-related diseases

Asbestos has been recognised as a potential health hazard since the 1940s. Of the two major species of asbestos; white asbestos (chrysotile) and blue asbestos (crocidolite), both of which are hazardous. The workers at extraction facilities are at the greatest risk of exposure to asbestos and, therefore, the development of asbestos-related diseases, commonly mesothelioma. However, other individuals at a high risk of exposure include asbestos-cement workers, insulation workers and ship-yard workers. Environmental exposure to asbestos can occur as a result of living in areas either characterised by natural outcrops of asbestos or asbestos-related materials, or those close to asbestos-producing or -using plants. Unfortunately, man-made fibre alternatives to asbestos, such as rock and slag-wool and glass wool, have also been shown to have a detrimental effect on human health. A characteristic of mesothelioma is that there is a long latency period (20-30 years) before the signs and symptoms of the disease become apparent. In addition, diagnosis of the disease can be difficult. The use of biological markers, such as tissue polypeptide antigen, may play a useful role in the early detection of the disease in individuals at risk.

Malignant pleural mesothelioma in Turkey, 2000–2002

Both asbestos and erionite related malignant pleural mesothelioma (MPM) is a serious health problem in Turkey. Erionite has a higher potency in the lung than asbestos and familial clustering of malignant mesothelioma suggests a genetic predisposition to this cancer among affected individuals. Neither Simian virus 40 (SV40) nor human herpes virus 8 (HHV-8) are co-factors in the pathenogenesis of environmentally induced mesothelioma. A survival advantage has been demonstrated in patients with asbestos-induced mesothelioma compared with erionite-induced mesothelioma. This together with the proliferation index (PI) can be used as an independent prognostic factor for patients with malignant pleural mesothelioma. It is envisaged that the application of these prognostic approaches together with the new TNM staging system will allow investigations to be more precisely carried out and evaluated.

Impaired cardiac autonomic functions in patients with environmental asbestos exposure: a study of time domain heart rate variability

Environmental asbestos exposure is related to diffuse pleural disease (thickening and calcification) and restrictive pulmonary disease. To assess cardiac autonomic system, we investigated the time domain heart rate variability (HRV) by Holter monitoring and their correlation with pulmonary function tests in patients with pleural disease caused by environmental asbestos exposure. We studied 45 patients (26 men, 19 women, aged 62.67 +/- 10.1 years) and 35 healthy patients who had similar sex and age profile to the patients (24 men, 11 women, aged 59.31 +/- 8.4 years). The asbestosis group was divided into 3 subgroups according to the severity of forced vital capacity (FVC) severe (group 1) (n = 12): FVC less than 50% of expected, moderate (group 2) (n = 16): FVC 64%-51% of expected and mild (group 3) (n = 17): FVC 65%-80% of expected. HRV parameters were significantly different among all groups (P<.0001). Comparing the 4 groups (subgroups and control group), group 1 had the lowest mean HRV values and controls had the highest mean HRV values (P<.0001). Severity of autonomic dysfunction was correlated with the severity of FVC and arterial oxygen pressure. Right ventricular end-diastolic internal diameter (RVEDID) and right ventricular end-systolic internal diameter (RVESID) values were significantly increased in patients (P <.0001, P < 0.0001, respectively). Pulmonary acceleration time (AcT) values were shorter in all patient groups than control group (P <.0001). It was shortest in group 1. Group 2 and 3 had shorter AcT values than control group. HRV parameters were correlated positively with AcT values and negatively with RVEDID and RVESID values. In conclusion, patients with restrictive pulmonary disease due to environmental asbestos exposure had autonomic dysfunction, which was correlated with the severity of restriction. This was thought to be the result of chronic hypoxia, pulmonary hypertension, and right ventricular enlargement.

Environmental Exposure to Asbestos in Eastern Turkey

In this study, the authors investigated the prevalence of asbestos-related disorders among the inhabitants of Güzelyurt, a town in Malatya, located in eastern Turkey. The authors examined river bed, white soil, and stucco samples taken from various locales in Güzelyurt, and they confirmed the presence of tremolite and chrysotile asbestos fibers. Subjects (N = 920; 449 males and 471 females) were examined by photofluoroscopy. Eighty-five patients (9.2%) had asbestos-related radiological findings; risk increased with age. Calcified pleural plaques were seen more frequently in individuals > or = 50 yr of age, compared with younger subjects (p < 0.01). Asbestos-related disorders were prevalent in the inhabitants of Güzelyurt, the population of which is exposed environmentally to asbestos--primarily the result of the stuccoing and whitewashing of houses with soil that contains asbestos.

Malignant mesothelioma due to environmental exposure to asbestos: follow-up of a Turkish cohort living in a rural area

STUDY OBJECTIVES

This study examines the incidence of malignant pleural mesothelioma (MPM) in a rural population of Turkey with environmental exposure to asbestos-contaminated soil mixtures (white soil).

DESIGN

A field-based epidemiologic study.

SETTING AND SUBJECTS

A cohort of villagers (the "Eskisehir" cohort) from 11 villages around Eskisehir in central Anatolia, who had been environmentally exposed to asbestos due to the use of white soil.

MEASUREMENTS

The mineral content and asbestos contamination of the white soil used in these villages was determined, as well as airborne fiber concentrations. Cohort members' details of age, sex, ambient exposure data, duration of residence in the villages, and hospital records, including pathologic diagnosis, were recorded.

RESULTS

The Eskisehir cohort consisted of 1,886 villagers. During the observation time, 377 deaths occurred and 24 MPM cases were diagnosed. Average annual mesothelioma incidence rates were 114.8/100,000 for men and 159.8/100,000 for women.

CONCLUSIONS

These data indicate that the risk of mesothelioma is 88.3 times greater in men and 799 times greater in women, respectively, in comparison to world background incidence rates.

Soils: their implications to human health

This paper reviews how the health of humans is affected by the world's soils, an association that to date has been under appreciated and under reported. Soils significantly influence a variety of functions (e.g. as a plant growth medium; its importance on the cycling of water; as a foundation for buildings) that sustains the human population. Through ingestion (either deliberate or involuntary), inhalation and dermal absorption, the mineral, chemical and biological components of soils can either be directly beneficial or detrimental to human health. Specific examples include: geohelminth infection and the supply of mineral nutrients and potentially harmful elements (PHEs) via soil ingestion; cancers caused by the inhalation of fibrous minerals or Rn gas derived from the radioactive decay of U and Th in soil minerals; and tetanus, hookworm disease and podoconiosis caused by skin contact and dermal absorption of appropriate soil constituents. Human health can also be influenced in more indirect ways as soils interact with the atmosphere, biosphere and hydrosphere. Examples include: the volatilisation of persistent organic pollutants (POPs) from soils and their subsequent global redistribution that has health implications to the Aboriginal people of the Arctic; the frequent detrimental chemical and biological quality of drinking and recreational waters that are influenced by processes of soil erosion, surface runoff, interflow and leaching; and the transfer of mineral nutrients and PHEs from soils into the plants and animals that constitute the human food chain. The scale and magnitude of soil/health interactions are variable, but at times a considerable number of people can be affected as demonstrated by the extent of hookworm infection or the number of people at risk because they live in an I-deficient environment. Nevertheless, it can often be difficult to establish definite links between soils and human health. This, together with the emergence of new risks, knowledge, or discoveries, means that there is considerable scope for research in the future. Such investigations should involve a multidisciplinary approach that both acquires knowledge and ensures its dissemination to people in an understandable way. This requires an infrastructure and finance that governments need to be responsive to.

Lung diseases due to environmental exposures to erionite and asbestos in Turkey

Asbestos deposits have been used locally by the rural inhabitants of Central and Southeastern Anatolia for domestic purposes for many years. Mineralogical analysis revealed that tremolite is the most prominent asbestos type found in the region. There is in addition another mineral fiber found particularly in three villages located in the Cappadocian region of Central Anatolia (zeolite villages). This is a non-asbestos mineral, which has been identified as the fibrous zeolite, erionite. This fiber is present in the volcanic tuffs, which are used as building stone. Hence, exposure to erionite fibers is always possible in the houses, annexes, and streets of the villages. It has been demonstrated that both asbestos and erionite cause a variety of benign and malignant chest diseases. Among the diseases, calcified pleural plaques (CPP) are the most frequently seen and may be used as an indicator of mineral fiber exposure. Asbestos and erionite exposure are the main causes of malignant mesotheliomas in Turkey. In zeolite villages malignant mesothelioma is responsible for more than 50% of the total deaths. A recent study showed that simian virus 40 is not a cofactor in the pathogenesis of environmental malignant mesothelioma in Turkey. An additional recent genetic-epidemiological study showed that there are some families, which are genetically predisposed to mesothelioma.

Prognostic factors in diffuse malignant pleural mesothelioma: effects of pretreatment clinical and laboratory characteristics

The aim of this study was to investigate the effects of various pretreatment clinical and laboratory characteristics on the survival of patients with diffuse malignant pleural mesothelioma (DMPM). One hundred histopathologically confirmed DMPM patients were evaluated. Fifty-nine were treated with chemoimmunotherapy while 41 who had refused chemoimmunotherapy received supportive therapy alone. The following pretreatment characteristics were evaluated in both univariate and multivariate Cox regression analyses: age, gender, Karnofsky performance score (KPS), histology asbestos exposure, presence of chest pain, dyspnoea, weight loss, symptom duration, smoking history, disease location, platelet count, haemoglobin, white blood cell (WBC) count, serum lactate dehydrogenase (LDH) and extent of disease (stage). Univariate analysis showed that patients with age > or = 75 years, male gender, smoking history advanced stages above stage I disease, KPS < 70, WBC count > or = 8450 and LDH level > or = 500 IU l(-1) have a worse prognosis. With multivariate Cox regression analyses, age > or = 75 years, advanced stages above stage I disease, KPS < 70 and LDH level > or = 500 IU l(-1) were found to be indicators of a poorer prognosis. In conclusion, in our study each of low performance status, older age, advanced stage disease, high LDH level and prognosis were found to be related.

Prognostic significance of flow cytometric DNA analysis in patients with malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) due to environmental exposure to asbestos and erionite is a relatively common cancer in Turkey. In this study, we investigated the value of flow cytometric (FCM) DNA analysis and other prognostic factors such as age and etiologic factor in the patients with MPM, treated with surgery+/-combination chemotherapy+/-radiotherapy. A total of 40 patients with a median age of 50 (range 30-68) were included in the study. Twenty-nine patients had asbestos exposure in etiology, while 11 had fibrous zeolite (erionite). Paraffin-embedded tumor specimens were studied by FCM for DNA analysis. Twelve patients (30%) had aneuploid tumors and 28 (70%) had diploid ones. Mean S-phase fraction (SPF; %) was 9.1+/-1.1 and proliferation index (PI, SPF+G2/M phase; %) was 11.3+/-0.9. While the median overall survival (OS) was 10+/-2 months (6-14; 95% CI), 1-year survival rate was 45.2%. Only PI was found to be statistically significant for OS in univariate analysis (P=0.013). PI was also found to be an independent prognostic factor for all patients (P=0.035). Aneuploidy was significantly higher in erionite group compared with asbestos group. Male predominance and poor survival were also prominent in erionite group, though not statistically significant. In conclusion, PI is an independent prognostic factor for patients with MPM and the biologic features of the disease may show differences with respect to different etiologies.

Percutaneous balloon pericardiotomy for patients with malignant pericardial effusion including three malignant pleural mesotheliomas

Ten patients were enrolled in this study to evaluate the therapeutic value of percutaneous balloon pericardiotomy in patients with symptomatic pericardial effusion secondary to malignant diseases. Four patients had breast cancer; 2 had lung cancer; 1 had non-Hodgkin's lymphoma; and 3 had malignant pleural mesothelioma, which is commonly seen in Central Anatolian region of Turkey. All patients underwent percutaneous balloon pericardiotomy with monofoil balloons (Mansfield, NuMed). No complication was seen during these procedures. In 3 patients, the balloon could not be expanded completely and was entered from a more lateral position by a second puncture. There was no recurrence of pericardial effusion in 6 of 7 patients without mesothelioma. After percutaneous balloon pericardiotomy, surgical subxiphoid windowing was performed due to drainage greater than 100 mL/day in a patient with lung cancer and in 1 patient with mesothelioma. In the other 2 patients with mesothelioma, recurrence of pericardial effusion was seen and then subxiphoid surgical windowing was performed due to development of cardiac tamponade in 1 of them. All the patients died 68.6 +/- 36 days later due to the primary malignancies. The survival time of patients with mesothelioma was shorter than that of the others (p < 0.05). These results suggest that percutaneous balloon pericardiotomy may be used in the treatment of patients with malignant pericardial effusion as an alternative to surgical pericardial window creation. But in patients with malignant pleural mesothelioma, the success rate of this procedure was lower than that of the others.

The role of environmental and occupational exposures in Turkish immigrants with fibre-related disease

Environmental exposure to tremolite and erionite causes endemic diseases of the lung and pleura in Turkey. This study aimed to evaluate the impact of these exposures and further occupational exposures on fibre-related diseases in Turkish immigrants living in Belgium. The study included 51 males and 17 females that emigrated < 1-38 yrs ago. Most of them (n=46) had nonmalignant pleural lesions, one had asbestosis and one had mesothelioma. Environmental asbestos exposure was likely for the majority of patients (60%), but there were also reports of possible occupational asbestos (n = 14) and erionite (n = 2) exposure. Tremolite was the main fibre type in bronchoalveolar lavage fluid (BALF). Elevated concentrations of amosite or crocidolite were detected in only two patients. The delay elapsed since the end of the environmental exposure had no influence on the asbestos body or the tremolite fibre concentrations in the BALF of Turkish immigrants. Most fibre-related diseases in Turkish immigrants are probably due to environmental rather than occupational exposure. Precise information about geographical origin and occupation should be obtained when investigating these patients. Mineralogical analysis of bronchoalveolar lavage fluid gives valuable information on the type and intensity of exposure, especially in patients with both environmental and occupational exposure.

Malignant mesothelioma in Japan: analysis of registered autopsy cases

In the Annual of the Pathological Autopsy Cases in Japan, issued by the Japanese Society of Pathology from 1958 to 1996, a total of 1,846 (0.17%) malignant mesothelioma cases (1,287 male, 558 female, 1 unknown) were registered among 1,056,259 autopsy cases. The frequency of mesothelioma (number of cases/total autopsy cases) was 0.10% (461/440,334) for the term 1958-1979, 0.18% (716/390,124) for 1980-1989, and 0.30% (669/225,801) for 1990-1996; the frequency of cases increased significantly over the time periods (p < .0001). Among 1,785 cases for which tumor sites were ascertained, there were 1,213 pleural mesothelioma (68.0%), 431 peritoneal (24.1%), 108 pericardial (6.1%), 6 tunica vaginalis testis (0.3%), and 28 "others" (1.6%). Histological cell type was noted in 598 cases; 245 (41.0%) were epithelial, 168 (28.1%) were biphasic, and 185 (30.9%) were sarcomatous. Seventy-three (0.007%) cases of malignant mesothelioma with asbestosis were found during the entire 39-y period. The frequency of those with asbestosis (number of cases/total autopsy cases) was 0.001% (5/440,334) for the term 1958-1979, 0.006% (27/390,124) for 1980-1989, and 0.018% (41/225,801) for 1990-1996; this increase over time was statistically significant (p < .0001). Researchers expect that cases of asbestos-related mesothelioma will increase in Japan in the future. Tumor sites and histological cell types of mesothelioma with asbestosis did not differ from those in individuals without asbestosis.

Environmental asbestos exposure and mesothelioma

Epidemiologic studies of mesothelioma have focused primarily on occupational exposures to asbestos. Nonoccupational exposure to asbestos can be grouped into three main categories: paraoccupational (familial), neighborhood, and true environmental exposures. Elevated mesothelioma rates not attributable to occupational exposures have been observed in asbestos mining and manufacturing areas. Asbestos is one of the most dangerous environmental carcinogens because of the small dose known to cause mesothelioma and the rapid lethality of the disease once it develops. Further research is needed to characterize the contribution and risk profile for environmental asbestos and mesothelioma, and for the development of public health policy.

Cisplatin, mitomycin, and interferon-alpha2a combination chemoimmunotherapy in the treatment of diffuse malignant pleural mesothelioma

STUDY OBJECTIVE

To investigate the therapeutic activity and toxicity of combination chemoimmunotherapy with cisplatin, mitomycin, and interferon (IFN)-alpha2a, by comparing the responses in a group of patients with diffuse malignant pleural mesothelioma (DMPM) to the responses in a control group of DMPM patients given supportive care alone.

DESIGN

Patients with histopathologically confirmed DMPM were evaluated for treatment with chemoimmunotherapy.

SETTING

After the initial evaluation, all patients received either chemoimmunotherapy or supportive care from the Osmangazi University Medical Faculty, Department of Chest Diseases.

PATIENTS

Forty-three patients with DMPM received chemoimmunotherapy until the end of the survey; 19 patients were given supportive therapy alone after refusing chemoimmunotherapy.

INTERVENTIONS

Drugs were administered according to the following schedule: IV cisplatin, 30 mg/m2 qd on days 1 and 2; IV mitomycin, 8 mg/m2 on day 1; and subcutaneous IFN-alpha2a, 4.5 million IU twice weekly. The courses were repeated every 4 weeks.

RESULTS

Overall, 232 chemoimmunotherapy cycles were administered. A total of 10 objective responses (ORs) in 43 patients (23%) were assessed, including 2 complete responses (5%), 4 partial responses, and 4 regressions. Seventeen patients had stable disease, and 16 patients had progression. The median survival time was 11.5 months for the 43 patients who received chemoimmunotherapy and 7.0 months for the 19 patients who received supportive therapy alone. The difference in survival times between the chemoimmunotherapy and supportive therapy groups was not significant. However, the median survival time for the patients who had OR was 21.3 months, which is significantly longer than that of the patients who received supportive care alone and that of patients with progressive disease (6 months). The toxicities associated with the treatment schedule of this study were, for the most part, tolerable.

CONCLUSIONS

The drug combination used in this study is moderately effective and well tolerated in patients with DMPM, especially in those who responded to the treatment.

Mesothelioma: cases associated with non-occupational and low dose exposures

OBJECTIVES

To estimate the importance of low dose exposure to asbestos on the risk of mesothelioma.

METHODS

A review of the literature.

RESULTS AND CONCLUSIONS

There is no evidence of a threshold level below which there is no risk of mesothelioma. Low level exposure more often than not contains peak concentrations which can be very high for short periods. There might exist a background level of mesothelioma occurring in the absence of exposure ot asbestos, but there is no proof of this and this "natural level" is probably much lower than the 1-2/million/year which has been often cited.

Environmental asbestos exposure and malignant pleural mesothelioma

Asbestos-related benign and malignant pleural diseases are endemic in some rural parts of central Turkey because of environmental exposure to asbestos fibres. We report here epidemiological data on 113 patients with diffuse malignant pleural mesothelioma (DMPM) diagnosed in our clinic in Eskişehir, located in central Turkey. Of the 113 patients, 59 were men and 54 women (male:female ratio = 1). Ninety-seven patients (86%) had non-occupational asbestos exposure; all were living in villages. Their mean age was 56 years. As the patients had been exposed to asbestos from birth, the latency period was equivalent to the age of the patients. Twenty-eight patients (29%) had lived in villages their entire lives. The other 69 (71%) had been born in a village but migrated to the city or had given up white-soil usage for various reasons. The mean exposure time was 55 years for those with a long exposure period and 25 years for those with a short exposure period, but there was no significant difference between the age of the disease appearance for both groups (55 and 56 years, respectively). Thus, the latency time of mesothelioma due to environmental exposure to asbestos was longer than that due to occupational exposure, but independent of the length of exposure. Soil samples from 67 villages were analysed, comprising a population of 10,120 villagers. Tremolite and some other types of asbestos were found. In conclusion, DMPM in our region is due to mainly to environmental exposure to asbestos. The risk is substantial as a large proportion of the villagers are exposed. After smoking, asbestos exposure is one of the most serious health hazards in our rural population.

Assessment of environmental asbestos exposure in Turkey by bronchoalveolar lavage

Environmental or domestic exposure to asbestos fibers originating from local soil is responsible for a high incidence of diseases in large rural areas of Turkey. Bronchoalveolar lavage fluids (BALF) were obtained for 65 Turkish subjects originating from these areas and for 42 Turkish controls. Asbestos bodies (ABs) and uncovered fibers (UFs) were quantified by phase contrast light microscopy. Total fiber burden was determined by transmission electron microscopy. The main asbestos types disclosed were tremolite and to a lesser extent chrysotile. AB and fiber concentrations were higher in environmentally exposed subjects (geometric mean [geometric standard deviation]: 5.20 [6.22] AB/ml, 444 [11.6] tremolite fibers/ml) than in control subjects (0.22 [1.45] AB/ml, 12.0 [15.4] tremolite fibers/ml) (p < 0.001). In subjects environmentally exposed in Turkey, AB burdens on tremolite were in the same range as those on commercial amphiboles in subjects occupationally exposed in Belgium. In Turkish subjects, values above either 1 AB/ml, 3 uncovered fiber/ml in light microscopy, or 300 fibers/ml in electron microscopy indicated usually an abnormal alveolar retention reflecting a significant cumulative exposure from environmental or domestic origin. These observations are probably valid for other areas in the world where diseases associated with environmental exposure to soil- derived asbestos fibers occur and for immigrants originating from these areas.

Pleurectomy/decortication for palliation in malignant pleural mesothelioma: results of surgery

OBJECTIVE

Surgery can only offer palliation in an attempt to slow the progression of malignant pleural mesothelioma (MPM). We want to assess the effectiveness and safety of pleurectomy/decortication in establishing a tissue diagnosis, and controlling pleural fluid accumulation and symptoms in patients with MPM.

METHODS

We reviewed our pleurectomy results in 100 patients with MPM over a 19 year period. Major symptoms were chest pain, cough and dyspnea, and radiographic findings included pleural mass, pleural fluid and constriction of involved hemithorax.

RESULTS

Approximately two thirds of the patients underwent surgery prior to tissue diagnosis. Eighty-nine patients had stage I and stage II disease, 8 and 81%, respectively. The patients underwent subtotal (44%) or total pleurectomy (56%). The surgical mortality rate was 1% (1/100) and the morbidity rate was 22%. Morbidity included prolonged air leak (n = 12), empyema (n = 6), reaccumulation of pleural fluid (n = 2) and wound infection (n = 2). Palliative results included dyspnea and cough relief in all patients, chest relief in 60 (85%) and pleural fluid control in 52 (96%) patients. Median survival was 17 months in MPM patients.

CONCLUSIONS

We conclude that pleurectomy/decortication safely provides both tissue diagnosis and effective of pleural effusion and symptoms and therefore excellent palliation in patients with MPM.

Two dose levels of ifosfamide in malignant mesothelioma

Thirty-one consecutive patients with histologically proven and symptomatic malignant mesothelioma were treated with two dose levels of ifosfamide. The first group of 15 patients were given 2.3 g/m2/day for 5 days (group A) and the following 16 patients were treated with 1.2 g/m2/day for 5 days of ifosfamide (group B). Treatment cycles were repeated every 3 weeks. While the partial response rate (PR) in group A was 38.5%, it was only 6.25% in group B (P > 0.05). The 95% confidence interval for the difference in PR rates was 3.3-61.2% > The overall survival (OAS) of groups A and B were similar (8 months and 9 months, respectively). Higher Grade 3-4 myelotoxicity was observed in group A when compared to group B (30.8% vs. 18.7%; P > 0.05). In conclusion, a favourable response rate could be achieved in malignant mesothelioma with high dose ifosfamide at the cost of increased toxicity.