Researchers investigating a potential causal relationship between asbestos exposure and peritoneal mesothelioma reviewed published data — clinical, epidemiological, and experimental — on the two. They suggested that all exposure levels are dangerous, and that no threshold of exposure to asbestos appears to be safe.
The review, by researchers from the School of Medicine and Public Health and the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison, is titled “Peritoneal Mesothelioma and Asbestos: Clarifying the Relationship by Epidemiology,” and published in Epidemiology.
Mesothelioma is a rare but aggressive cancer of the specialized cells that line body organs and structures, and malignant mesothelioma remains stubbornly resistant to existing treatments — namely, radiation and chemotherapy. Exposure to asbestos, a group of minerals found naturally as fiber bundles in soil and rocks, is the leading cause of malignant mesothelioma, especially pleural mesothelioma. Occupational exposure, especially among men, is thought to account for the majority of cases.
Peritoneal mesothelioma is rarer than pleural mesothelioma, accounting for about 5 percent to 20 percent of all cases, although rates have been increasing, especially among women. The causal relationship between asbestos and peritoneal mesothelioma remains controversial, as the scientific community has not yet reached a consensus regarding causation, a potential threshold of exposure, and which population is more at risk.
In the review, researchers sought to clarify the role of asbestos in the development of peritoneal mesothelioma by evaluating the epidemiology and experimental data available, and also by focusing on the type of fiber, disease occurrence in women, and dose issues. The researchers first highlight that this type of mesothelioma is difficult to diagnose, as the malignancy can be mistaken for ovarian, colon, and other abdominal cancers. According to the literature, women have a higher proportion of peritoneal than pleural mesothelioma, patients with peritoneal are significantly younger than those with pleural, and median survival for peritoneal mesothelioma is shorter than pleural.
Moreover, it is clear from the existing studies that occupational exposure, in fields such as mining or construction, or from working in places with asbestos, contributes to peritoneal mesothelioma development. Other exposures, such as neighborhood asbestos exposure, have also been documented. Amphibole and chrysotile asbestos are noted as causes of mesothelioma and deaths for both genders in many countries. As there is currently no dose-response established for asbestos and peritoneal mesothelioma, researchers suggest, as a precaution, that all exposures should be considered dangerous and potentially the cause of malignancy.
“The use of asbestos is continuing in many countries of the world, particularly in India and others where worker protections are often lax, and thus the issues reviewed here are of public health importance to prevent future peritoneal mesotheliomas. Post-occupational health surveillance of asbestos workers is necessary for early detection and treatment of cancer in future victims of work that led to asbestos exposures,” the researchers conclude.
According to the Mesothelioma Cancer Alliance, only 5 percent to 10 percent of mesothelioma patients live five years after diagnosis, and about 43,000 people worldwide die from the disease each year.