Malignant Mesothelioma

In this article, we will discuss Malignant Mesothelioma (Epidemiology). So, let’s get started.

Malignant Mesothelioma (Epidemiology)

Malignant mesothelioma (MM) is a rare tumor, rare tumors are those with incidence <6/100,000 per year (RARECARE), that originates from the inner lining of the body’s serous cavities (pleura, peritoneum, pericardium, and vaginal tunic of the testicle). It has a bad prognosis and is characterized by a short survival (about 12 months). It is considered a “sentinel event” of past exposure to asbestos in all areas where exposure to other risk factors for MM can be ruled out. Because of their physical characteristics, asbestos fibers remain in the lung, regional lymph nodes,
and pleural cavity and induce chronic inflammation through the production of reactive oxygen/nitrogen species. As a consequence, immunocompetent cells can have their cellular and molecular features altered by chronic and recurrent encounters with asbestos fibers, all of which eventually lead to decreased tumor immunity. Potential cofactors for the development of MM are also exposure to other elongated mineral particles (EMPs) such as synthetic materials (ceramics, nanoparticles), ionizing radiation, and SV-40 virus infections. Genetic factors can also play a role in the onset of MM. Indeed, family clusters in blood relatives have been described. Many studies have shown that polymorphism in the genes involved in xenobiotic and oxidative metabolism or in DNA repair processes may play an important role in the etiology and pathogenesis of these diseases. Early symptoms of MM are usually nonspecific, and diagnosis may be delayed. There are a number of comprehensive studies in the literature investigating potential biomarkers for the early diagnosis of MM in symptomatic patients exhibiting past exposure to asbestos. Among these, Mesothelin is one of the several well-known biomarkers used in the diagnosis of pleural MM. Other studies showed that miRNA expression in tissue and body fluids is aberrant in various tumors, revealing miRNAs as promising diagnostic biomarkers. It is a disease characterized by a long latency interval between the onset of exposure and the appearance of the disease (from 20 to 40 years and over). The average overall survival rates (OS) range from 4 to 13 months for untreated patients and from 6 to 18 months for treated patients, only 7% of patients are still alive at five years from the diagnosis. A better survival was reported with multimodal surgical-based therapy. The Surveillance, Epidemiology, and End Results (SEER) database was explored from 1973 to 2009 to identify all 14,228 cases with diagnostic certainty. In multivariate analyses, female sex, younger age, early stage, and treatment with surgery were independent predictors of longer survival. Despite the development of surgical techniques, prognosis has not improved in the last four decades. After the cessation of use at work, the public health danger is the presence of both large quantities of materials containing asbestos in a friable matrix, in civil and industrial buildings as well as in transport sector facilities (e.g., naval), and significant quantities of material containing asbestos in a compact matrix whose progressive deterioration can cause the release of fibers with consequent risk to human health. In addition, asbestos is extremely widespread and can be hidden in living areas and in everyday objects (ironing board covers, curtains, cardboard, toys, etc.). The analysis of data provided by epidemiological studies has shown that the risk of MM increases with the increase in exposure to asbestos fibers, so there are no doubts regarding the proportional relationship between cumulative dose and MM frequency. It is also agreed that the most recent exposure has a lower role, but not a null one. As with all carcinogens, however, there is no safety “threshold” below which there is no risk. The incidence is increasing worldwide, and it is expected to reach its peak in the coming years, especially in developing countries where asbestos is still used and often without adequate control measures. Because of the long latency period of the disease, deaths are expected to peak between 2015—2025 and, according to some experts, even in 2040.

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