Ecological association between asbestos-related diseases and historical asbestos consumption: an international analysis

Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2'-deoxyguanosine (80HdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFbeta) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 80HdG in DNA. Elevated levels of 80HdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [> 60(ff/cm3) x years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

Recent mortality from pleural mesothelioma, historical patterns of asbestos use, and adoption of bans: a global assessment

BACKGROUND

In response to the health risks posed by asbestos exposure, some countries have imposed strict regulations and adopted bans, whereas other countries have intervened less and continue to use varying quantities of asbestos.

OBJECTIVES

This study was designed to assess, on a global scale, national experiences of recent mortality from pleural mesothelioma, historical trends in asbestos use, adoption of bans, and their possible interrelationships.

METHODS

For 31 countries with available data, we analyzed recent pleural mesothelioma (International Classification of Diseases, 10th Revision) mortality rates (MRs) using age-adjusted period MRs (deaths/million/year) from 1996 to 2005. We calculated annual percent changes (APCs) in age-adjusted MRs to characterize trends during the period. We characterized historical patterns of asbestos use by per capita asbestos use (kilograms per capita/year) and the status of national bans.

RESULTS

Period MRs increased with statistical significance in five countries, with marginal significance in two countries, and were equivocal in 24 countries (five countries in Northern and Western Europe recorded negative APC values). Countries adopting asbestos bans reduced use rates about twice as fast as those not adopting bans. Turning points in use preceded bans. Change in asbestos use during 1970-1985 was a significant predictor of APC in mortality for pleural mesothelioma, with an adjusted R(2) value of 0.47 (p < 0.0001).

CONCLUSIONS

The observed disparities in global mesothelioma trends likely relate to country-to-country disparities in asbestos use trends.

Gene-environment interactions in the development of complex disease phenotypes

The lack of knowledge about the earliest events in disease development is due to the multi-factorial nature of disease risk. This information gap is the consequence of the lack of appreciation for the fact that most diseases arise from the complex interactions between genes and the environment as a function of the age or stage of development of the individual. Whether an environmental exposure causes illness or not is dependent on the efficiency of the so-called “environmental response machinery” (i.e., the complex of metabolic pathways that can modulate response to environmental perturbations) that one has inherited. Thus, elucidating the causes of most chronic diseases will require an understanding of both the genetic and environmental contribution to their etiology. Unfortunately, the exploration of the relationship between genes and the environment has been hampered in the past by the limited knowledge of the human genome, and by the inclination of scientists to study disease development using experimental models that consider exposure to a single environmental agent. Rarely in the past were interactions between multiple genes or between genes and environmental agents considered in studies of human disease etiology. The most critical issue is how to relate exposure-disease association studies to pathways and mechanisms. To understand how genes and environmental factors interact to perturb biological pathways to cause injury or disease, scientists will need tools with the capacity to monitor the global expression of thousands of genes, proteins and metabolites simultaneously. The generation of such data in multiple species can be used to identify conserved and functionally significant genes and pathways involved in gene-environment interactions. Ultimately, it is this knowledge that will be used to guide agencies such as the U.S. Department of Health and Human Services in decisions regarding biomedical research funding and policy.

[Asbestos clinics and asbestos health examinations--findings from a questionnaire survey of implementing organizations]

In June 2005 the press reported that many former employees of a company which used asbestos, and individuals who lived near the company's factory, had been diagnosed with mesothelioma. This finding triggered concern and alarm in Japan. In response, many "asbestos clinics" were formed, and recognized medical institutions began to implement asbestos-related health examinations. We conducted a nationwide questionnaire survey to evaluate the activities in, and the challenges for, these medical institutions. We received 137 valid responses, more than half of which were from clinics and hospital-based "asbestos clinics" instigated after the "Kubota shock." Among the asbestos exposure history interviewing practices, job histories of the interviewee were prioritized, over place of residence, and possible exposure of family members. Standard questionnaires were utilized by over 70% of respondents. The practitioners reported problems with lack of manpower and evaluation of asbestos exposure. Examinees consulted attending physicians on a wide range of matters including asbestos-related diseases, asbestos exposure, and financial compensation. It is predicted that asbestos-related diseases in general, and mesothelioma in particular, will increase in the future. Accordingly, early detection and treatment should be accorded high priority. The organizations we surveyed have important roles to play. Although resources are limited, effective diagnosis and treatment are essential, and a system assisting organizations to make accurate and efficient identification of asbestos exposure hazards is imperative.

Multiple mechanisms of telomere maintenance exist and differentially affect clinical outcome in diffuse malignant peritoneal mesothelioma

PURPOSE

This study aims to investigate the prevalence of the two known telomere maintenance mechanisms, telomerase activity (TA) and alternative lengthening of telomeres (ALT), and to assess their prognostic relevance in diffuse malignant peritoneal mesothelioma (DMPM).

EXPERIMENTAL DESIGN

In 44 DMPM specimens obtained from 38 patients, TA was determined using the telomeric repeat amplification protocol and ALT was detected by assaying ALT-associated promyelocytic leukemia nuclear bodies. The prognostic significance of telomere maintenance mechanisms was analyzed by Cox regression in the overall series and in a subset of 29 patients who underwent a uniform treatment regimen consisting of cytoreductive surgery and hyperthermic i.p. chemotherapy.

RESULTS

Telomere maintenance mechanisms were detectable in 86.4% of DMPM: ALT or TA alone was found in 18.2% or 63.6% of lesions, respectively, whereas two cases (4.6%) were ALT+/TA+. TA and ALT proved to be inversely associated (P = 0.002). In the overall series, TA was prognostic for 4-year relapse (TA+ versus TA-, hazard ratio, 3.30; 95% confidence interval, 1.23-8.86; P = 0.018) and cancer-related death (TA+ versus TA-, hazard ratio, 3.56; 95% confidence interval, 1.03-12.51; P = 0.045), whereas ALT failed to significantly affect clinical outcome. These results held true also in the subset of patients submitted to uniform treatment with cytoreductive surgery and hyperthermic i.p. chemotherapy.

CONCLUSIONS

Our results indicate that both known telomere maintenance mechanisms, TA and ALT, are present in DMPM and differentially affect patient prognosis.

Molecular and genetic changes in asbestos-related lung cancer

Asbestos-exposure is associated with an increased risk of lung cancer, one of the leading causes of cancer deaths worldwide. Asbestos is known to induce DNA and chromosomal damage as well as aberrations in signalling pathways, such as the MAPK and NF-kappaB cascades, crucial for cellular homeostasis. The alterations result from both indirect effects through e.g. reactive oxygen/nitrogen species and direct mechanical disturbances of cellular constituents. This review describes the current knowledge on genomic and pathway aberrations characterizing asbestos-related lung cancer. Specific asbestos-associated molecular signatures can assist the development of early biomarkers, molecular diagnosis, and molecular targeted treatments for asbestos-exposed lung cancer patients.

Incidence and descriptive epidemiology of mesothelioma in the United States, 1999-2002

To estimate the recent incidence of mesothelioma in the United States and characterize its descriptive epidemiology, incidence data were obtained from the National Program of Cancer Registries (NPCR) and the Surveillance, Epidemiology and End Results (SEER) Program. Age-adjusted incidence rates and 95% confidence intervals were calculated. The U.S. incidence was 1.11 cases per 100,000 persons. Most cases occurred among older, white males. However, 173 cases (< 2%) occurred in persons younger than 40. The proportion of women with peritoneal mesothelioma was triple that of men (14.8% vs 5.4%). Of 40 reporting states, 11 had incidence rates significantly higher than the national rate.