Veel mensen zijn intensief in contact met asbest geweest. Een klein aantal van hen krijgt mesothelioom. Drie recent gepubliceerde studies wijzen erop dat erfelijke aanleg een verhoogde gevoeligheid kan geven voor het krijgen van deze aandoening. In een Italiaans onderzoek werd een verhoogde kans op mesothelioom gevonden bij mensen met een lage activiteit van het mEH-enzym. Turkse onderzoekers vonden dat mesothelioom in bepaalde families wel voorkomt en in andere families niet, terwijl de blootstellingsniveaus aan erioniet, een asbestachtig materiaal, gelijk waren. Amerikaanse onderzoekers vergeleken een groep mesothelioompatiënten met drie andere groepen asbestblootgestelden. De mesothelioompatiënten hadden meer eerstelijns-familieleden met kanker en bij hen was vaker een tweede kanker vastgesteld. Bron: Laan, G. van der (2006). Asbestkanker en genethisch bepaalde gevoeligheid. TBV 14, 7, september 2006, pag. 298. Ohar, J.A. et al. (2006). Identification of a mesothelioma phenotype. Respitory Medicine, article in press.
Neri, M., Filiberti, R, Taioli, E. et al., (2005). Pleural malignant mesothelioma, genetic susceptibility and asbestos exposure. Mutat Res , 592, 36-44.
Pleural malignant mesothelioma (MM) is a rare but extremely aggressive cancer. The limited impact of standard therapeutic treatments on survival rates makes the identification of factors that increase the individual risk a leading priority. The high proportion of cases explained by exposure to asbestos has guided intervention policies to an effective ban of this compound from our environment. However, MM cannot be solely attributed to this agent, and the role of predisposing factors and their interaction with asbestos exposure is increasingly studied. The role of mEH, GSTM1, GSTT1, NAT2, and CYP1A1 genotypes in modulating susceptibility to MM was examined in a case-control study of 80 subjects with a confirmed diagnosis of MM and 255 controls. Subjects with low mEH activity showed a significantly increased risk of MM (OR, 2.51. 95% CI, 1.11-5.68). The association was stronger in the group with low asbestos exposure (OR, 7.83. 95% CI, 0.98-62.60). A significant increased risk of MM was also found in NAT2 fast acetylators (OR, 1.74. 95% CI, 1.02-2.96). The presence of synergisms between genotypes, i.e., mEH and NAT2 (LRT for heterogeneity p<0.023), mEH and GSTM1 (LRT p<0.061), and NAT2 and GSTM1 (LRT p<0.049), combined with the interaction observed with exposure to asbestos, suggests the presence of gene-environment and gene-gene interactions in the development of MM, although the size of the study group does not allow to draw clearcut conclusions. Since genetic polymorphisms can also modify the extent of genetic damage occurring in subjects exposed to carcinogens, we measured the frequency of micronuclei in peripheral blood lymphocytes of a subgroup of MM cases. The limited number of cases (28) did not allow to observe significant effects. In conclusion, these results strengthen the hypothesis that individual susceptibility to MM can be modulated by the interaction between polymorphic genes involved in the metabolism and the intensity of asbestos exposure. Dogan AU, Baris YI, Dogan M, Emri S, Steele I, Elmishad AG, Carbone M., (2006). Genetic predisposition to fiber carcinogenesis causes a mesothelioma epidemic in Turkey. Cancer Research, mei 15.66(10):5063-8.
Malignant mesothelioma in the western world is often associated with asbestos exposure. It is a relatively rare cancer that causes approximately 2,500 deaths yearly in the United States and 1,000 deaths yearly in the United Kingdom. In contrast, among people born in the Cappadocian (Turkey) villages of Tuzkoy, Karain, and “Old” Sarihidir, approximately 50% of deaths are caused by malignant mesothelioma. This epidemic has been attributed to erionite exposure, a type of fibrous zeolite mineral commonly found in this area of Turkey. In these three villages, malignant mesothelioma occurs in certain houses but not in others. The hypothesis was that a unique and more carcinogenic erionite was present in certain houses and caused malignant mesothelioma. We determined the X-ray diffraction pattern and the crystal structure of erionite from malignant mesothelioma villages and compared the results with the erionite samples from nearby non-malignant mesothelioma villages and from the United States. We found the same type of erionite in Cappadocian villages, with or without a malignant mesothelioma epidemic, in households with high or no incidence of malignant mesothelioma and in the United States. Pedigree studies of the three malignant mesothelioma villages showed that malignant mesothelioma was prevalent in certain families but not in others. When high-risk malignant mesothelioma family members married into families with no history of it, malignant mesothelioma appeared in the descendants. Genetically predisposed family members born and raised outside the malignant mesothelioma villages did not seem to develop malignant mesothelioma. In summary, pedigree and mineralogical studies indicate that the malignant mesothelioma epidemic is caused by erionite exposure in genetically predisposed individuals. This is the first time that genetics is shown to influence mineral fiber carcinogenesis.
Ohar, J.A. et al. (2006). Identification of a mesothelioma phenotype. Respitory Medicine, article in press.
Despite the strong association of asbestos exposure to mesothelioma, only a fraction of persons exposed develop this neoplasm which is characterized by long latency and shortened survival. Familial clustering implicates both exposure and genetic predisposition as causative, but a biologically relevant mesothelioma phenotype essential to genetic analysis has not been defined. To identify a more extensive set of traits that would define a mesothelioma phenotype for the purpose of genetic analysis, we set to determine characteristics that distinguish mesothelioma patients from others exposed to asbestos and to identify factors that predict the presence of mesothelioma over other mesenchymal tumors of the peritoneum and carcinoma metastatic to the pleura. We compared demographics in four asbestos-exposed groups (controls n=347, bronchogenic cancer n=67, mesothelioma n=179 and benign asbestos-induced lung disease (BALD) n=3757). Within the mesothelioma group, we compared traits to identify characteristics associated with shortened survival. We found that compared to other asbestos-exposed groups, subjects with mesothelioma were younger at first asbestos exposure, had a greater risk of a second cancer diagnosis (odds ratio=3.29), had a longer disease latency, and had a greater risk of cancer among first-degree relatives (point estimate for risk 2.93. 95% CI 2.5-3.5). Thoracic tumor location, work exposure and male gender were consistently associated with shortened survival (1.9+/-1.3 years). We conclude that thoracic tumor location, work exposure, male gender, long latency, early age at first exposure, presence of a second cancer, and first-degree relative with cancer define a phenotype that sets mesothelioma patients with a short survival apart from other asbestos-exposed individuals. We propose that this phenotype be applied to candidate gene analysis.