The diagnosis of MM was made by means of thoracoscopy or video-assisted thoracoscopic surgery (VATS) in patients with pleural MM and by means of laparoscopy or laparotomy in peritoneal MM. The diagnosis was confirmed histopathologically by an experienced pathologist.2 (link)
The diagnosis of “no asbestos related disease” in the control group was confirmed by the experts of the Board for Recognition of Occupational Asbestos Diseases at the Clinical Institute of Occupational Medicine, which consisted of an occupational physician, pulmonologist and radiologist, as previously described. 16 (link)
A personal interview with each of the subjects was conducted to get the data about smoking using a standardized questionnaire. 29 (link) To determine asbestos exposure, a semiquantative method was used. For all the controls, data on cumulative asbestos exposure in fibres/cm3-years were available from the previous study. 29 (link) Data on cumulative asbestos exposure were also available for 27 MM patients. Based on these data, we divided the subjects into three groups: low (< 11 fibres/cm3-years), medium (11–20 fibres/cm3-years) and high (> 20 fibres/cm3-years) asbestos exposure. For the rest of the patients with MM, a thorough work history was obtained and where enough information was available, their exposures were compared with those from the group of patients with known cumulative asbestos exposure and were correspondingly divided into three groups with presumed low, medium and high asbestos exposures. 2 (link) Thus, 37 MM patients were assigned to one of these three groups, but for 95 MM patients epidemiological data were not sufficient to allow the assignment of patients to one of the groups; consequently, they were only categorized as exposed or non-exposed. The influence of asbestos exposure on MM risk was determined in the subgroup of patients where the asbestos exposure was known or could be assessed.
DNA of the MM patients and some controls without asbestos related diseases was available from our previous studies2 (link),30 (link), DNA of the rest of the controls was isolated from peripheral venous blood samples using FlexiGene DNA kit (Qiagen, Hilden, Germany).
Real-time polymerase chain reaction (PCR) based TaqMan assays were used for the analysis of NQO1 rs1800566, CAT rs1001179, SOD2 rs4880 and hOGG1 rs1052133 polymorphisms as recommended by the manufacturer (Thermo Fisher Scientific, SNP genotyping assay C_2091255_30, C_11468118_10, C_8709053_10 and C_3095552_1_, respectively). Genotyping was performed blinded regarding the study endpoints and repeated in 20% of samples to check for genotyping accuracy and all the genotypes were concordant. Amplification was not successful in 11 subjects for NQO1, in 2 for CAT, in 6 for SOD2 and in 7 subjects for hOGG1 polymorphism.
The diagnosis of “no asbestos related disease” in the control group was confirmed by the experts of the Board for Recognition of Occupational Asbestos Diseases at the Clinical Institute of Occupational Medicine, which consisted of an occupational physician, pulmonologist and radiologist, as previously described. 16 (link)
A personal interview with each of the subjects was conducted to get the data about smoking using a standardized questionnaire. 29 (link) To determine asbestos exposure, a semiquantative method was used. For all the controls, data on cumulative asbestos exposure in fibres/cm3-years were available from the previous study. 29 (link) Data on cumulative asbestos exposure were also available for 27 MM patients. Based on these data, we divided the subjects into three groups: low (< 11 fibres/cm3-years), medium (11–20 fibres/cm3-years) and high (> 20 fibres/cm3-years) asbestos exposure. For the rest of the patients with MM, a thorough work history was obtained and where enough information was available, their exposures were compared with those from the group of patients with known cumulative asbestos exposure and were correspondingly divided into three groups with presumed low, medium and high asbestos exposures. 2 (link) Thus, 37 MM patients were assigned to one of these three groups, but for 95 MM patients epidemiological data were not sufficient to allow the assignment of patients to one of the groups; consequently, they were only categorized as exposed or non-exposed. The influence of asbestos exposure on MM risk was determined in the subgroup of patients where the asbestos exposure was known or could be assessed.
DNA of the MM patients and some controls without asbestos related diseases was available from our previous studies2 (link),30 (link), DNA of the rest of the controls was isolated from peripheral venous blood samples using FlexiGene DNA kit (Qiagen, Hilden, Germany).
Real-time polymerase chain reaction (PCR) based TaqMan assays were used for the analysis of NQO1 rs1800566, CAT rs1001179, SOD2 rs4880 and hOGG1 rs1052133 polymorphisms as recommended by the manufacturer (Thermo Fisher Scientific, SNP genotyping assay C_2091255_30, C_11468118_10, C_8709053_10 and C_3095552_1_, respectively). Genotyping was performed blinded regarding the study endpoints and repeated in 20% of samples to check for genotyping accuracy and all the genotypes were concordant. Amplification was not successful in 11 subjects for NQO1, in 2 for CAT, in 6 for SOD2 and in 7 subjects for hOGG1 polymorphism.
