Malignant pleural mesothelioma (Respiratory system)

Introduction and definition – Mesothelioma is a rare and aggressive tumor associated with exposure to asbestos by inhalation or oral intake during life. It is made up of mesothelial cells of the simple flaky epithelium lining the membranes around individual body cavities or organs, the lungs (lung tissue-pleura), abdominal cavity (abdominal-peritoneum), heart (cardiac tissue-pericardium) and tunics of the vaginalis membrane around the testis. There are 4 types of mesothelioma: pleural, peritoneal, pericardial and testicular. The focus of this text will be on mesothelioma pleura, which is the most dominant frequency with more than ¾ of all mesotheliomas. The tumor has a very bleak prognosis of fatal outcome, it is still incurable, but the hope is given by the fact that there are various new methods in the experimental research and clinical study phase that can improve current treatment prognoses. Current therapeutic modalities prolong survival, but most often do not provide a complete cure. There is also benign mesothelioma that is localized and does not diffuse as malignant mesothelioma.

Epidemiology

The disease affects the elderly population over 45 years because the disease occurs after a long latent period of 20 to 50 years from the time of exposure to asbestos. It accounts for about 2% of all malignancies, affecting 1 in 250,000 people in the general population. The highest incidence occurs in people with occupational exposure to asbestos. It more often affects the male population than the female population, which is explained by the fact that men are more likely to engage in these occupations that are at risk.

Asbestos is a material that used to be used in the construction of building insulation material, shipbuilding, heavy industry, and ore mining. It is precisely the workers in these industries who are most affected by mesothelioma: construction workers, miners, industrial workers, artisans, firefighters as well. An interesting occurrence of mesothelioma in family members of rye asbestos-infestation in these industries who did not have direct contact with asbestos. Specifically, asbestos dust accumulates on the skin, hair and clothing of these people, who later in such an indirect way expose people from their environment to asbestos fibers. Mesothelioma is also intensifying in the places where the mines of this material are located, because of the exploitation, air contamination and exposure of the residents who are not employed at these facilities are exposed.  

Pathogenesis and risk factors

Asbestosis by far the most important factor influencing the development of mesothelioma! It takes a very long time to develop, the latency period from asbestos exposure to tumor development is 20 to 50 years, but when it develops it is extremely fast and aggressive. It is correlated with dose and length of exposure, so higher and longer exposures carry greater risk. Some forms of asbestos fibers are more pathogenic than others. Persons exposed to asbestos for more than 20 years are considered to be at particularly high risk. Workers inhale asbestos fibers, which are very resistant to environmental effects. Intact asbestos-containing material is not dangerous, however, by treatment and damage it creates asbestos dust from its fibers, which is inhaled by humans and thus builds up in the lungs. Lymphatic asbestos enters the pleura and mesothelial cells that make up this envelope around the lung, both in the pleura leaf, visceral and parietal. These fibers cause inflammation and irritation of the mesothelium and consequently damage and mutation of the DNA of the mesothelial epithelium at the irritation site. The cell cycle of these cells is also disrupted, uncontrolled divisions occur, and the production of free radicals in the field of chronic inflammation increases, further damaging the cells. All these effects together affect malignant alteration and mesothelioma formation. The production of free radicals in the field of chronic inflammation increases, further damaging the cells. All these effects together affect malignant alteration and mesothelioma formation.  All these effects together affect malignant alteration and mesothelioma formation.

Smoking is also an important factor in the development of mesothelioma. It does not in itself cause its occurrence, but persons who are simultaneously exposed to asbestos are far more likely to develop this malignancy than non-smokers. Synergies between these two risk factors have been observed and it is very important to prevent them and to prevent the disease.

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