Mesothelioma – classification of stages, prognosis

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Mesothelioma is an aggressive malignant tumor that develops on the surface of the pleura and sometimes grows locally. However, more often it diffusely spreads along the inner surface of the pleura and penetrates into the pericardium. Usually at patients pleural effusion is observed and bilateral tumor is sometimes formed.

 

PLEURAL MESOTHELIOMA | Mesothelioma - classification of stages, prognosis

 

 

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In some cases, primary peritoneal mesothelioma develops, which does not affect the pleura; at the same time, in patients with a primary lesion of the pleura, symptoms of peritoneal damage sometimes appear. In the past, most patients with mesothelioma had long-term exposure to asbestos, and tumor development is usually preceded by a long latent period, sometimes up to 20 years.

 

The incidence of mesothelioma is increasing, apparently due to the increasing prevalence of asbestos in various areas of our lives. It is estimated that in the UK in 2000, asbestos caused 1,500 deaths, and by 2020 this figure should double. Although strict measures have been taken over the past 10 years to limit the use of asbestos, the danger of this material has not yet been adequately assessed.

Until 2020 in the UK, an increase in diseases associated with asbestos exposure to the body is predicted. It is believed that the most carcinogenic mineral is crocidolite. In mesothelioma, the SV 40 virus (poliomavirus) is often detected. However, its role in the onset and development of tumors remains unclear.

 

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Mesothelioma pathogenesis

Mesothelioma is a tumor of the sarcomatous type, and the fibrous and epithelioid elements in it can be so anaplastic that often the neoplasm cannot be distinguished from a poorly differentiated carcinoma. The severity of anaplastic changes does not coincide with the clinical symptoms observed during the development of the tumor. In differential diagnosis, it is very difficult to distinguish mesothelioma from adenocarcinoma.

 

Mesothelioma is characterized

Mesothelioma is characterized by local growth, and usually tumors affect the ribs and chest wall. Early spread of the tumor into the intercostal ligaments is the cause of the development of severe characteristic pain. The tumor also invades the diaphragm , invades regional lymph nodes, and usually metastasizes via the hematogenous route.

It has now been established that the most important autocrine tumor growth factors are vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF); hyperexpression of the epidermal growth factor was noted. Therefore, chemotherapy drugs that control the production of these factors, such as thalidomide, bevacu-zimab (Avastin), and gefitinib, show a curative effect.

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A system for determining the stage of development of mesothelioma has been developed , which makes it possible to predict the course of the disease and plan therapeutic measures. The clinical picture of mesothelioma Patients complain of increasing chest pain , sometimes very painful, and the onset of shortness of breath during exercise. Shortness of breath takes on a continuous progressive character, and often patients begin to suffocate, even while at rest. On examination, they show signs of reduced chest mobility and pleural effusion. The typical picture of asbestos dust damage on the radiograph looks like multiple rashes on the pleura, usually associated with pleural effusion.

 

Mesothelioma is characterized

Mesothelioma is characterized by invasion of the pleura and spread of the tumor into the mediastinum. In this case, there is a “squeezing” of the ribs, which occurs due to compression of their growing tumor. Diagnosis of mesothelioma The initial diagnosis is usually confirmed after a pleural biopsy. In cases of extensive tumor spread and the impossibility of resection, diagnostic thorectomy should be avoided.

Usually, in this case, the tumor spreads to the surgical suture, which causes additional pain to the patient. To assess the spread of the tumor, CT is necessary, especially of the nearby pleura and pericardium. Mesothelioma treatment Mesothelioma is difficult to treat. Surgical intervention is possible only in a small number of cases of a localized tumor, although a therapeutic effect is achieved.

Since relapses are common, most surgeons prefer to perform a major resection if possible, removing part of the chest wall, diaphragm, pericardium, and, if necessary, the adjacent lobe of the lung. Radiation therapy , in general, is ineffective, although in some cases, after irradiation, tumor growth slows down.

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Irradiation of the entire surface of the pleura is difficult due to the proximity of the lungs, but the emergence of new methods of tangential irradiation allows us to hope for further development of radiation therapy techniques. A variety of drugs have been used to treat patients with mesothelioma, but until recently, only a short-term effect was achieved.

Among the most effective drugs are (approximate effectiveness is indicated in brackets): methotrexate (30%), vinorelbine (20%), mitomycin (20%), cisplatin (15%), doxorubicin (15%), docetaxel (10%), gemcitabine (10%). Much higher efficiency (40-50%), although in small groups of patients, showed new analogues of folic acid – pemetrexed and raltitrexed.

These drugs can be considered the most effective in the treatment of mesothelioma. Pemetrexed is a folic acid analogue that inhibits at least three enzymes involved in nucleic acid synthesis. In Phase 3 clinical trials, the drug has shown over 40% efficacy and has recently been approved for clinical use in combination with cisplatin in the treatment of malignant pleural mesothelioma.

This is an outstanding result in the treatment of such a difficult tumor as mesothelioma, and the new drug is the most effective known to date. Currently, patients with mesothelioma can be given a combination of pemetrexed with cisplatin. The combination of gemcitabine with cisplatin was effective in approximately 35% of patients, however, according to the results of randomized trials, it did not exceed cisplatin in terms of effectiveness.

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There are reports of the effectiveness of a-interferon. Approximately 20% of patients had an effect with the combined use of interferon with cisplatin, and in some patients it manifested itself for many months. Additional studies are needed to evaluate the effectiveness of other combinations of chemotherapy drugs.

Nevertheless, chemotherapy is now gaining a place among the treatments for such a complex tumor as mesothelioma. In a number of cases, intrapleural chemotherapy has been tried to control tumor spread, but the results have been disappointing.

 

The median overall survival of patients is a little over 1 year; unfavorable prognostic factors include: the presence of a tumor of the sarcomatous type, poor general condition of the patient and lymphocytosis. Men have a less favorable prognosis. Less than 15% of patients live for five years. The median survival for inoperable patients receiving maintenance therapy is about 6 months.

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Such unfortunate results indicate the need to introduce strict control over the use of products containing asbestos. Patients with a tumor who have worked in the asbestos industry in the past are usually considered the most likely candidates for appropriate legal compensation.

 

Recently, new legal norms have been adopted in the British legislation in this direction. Thanks to this, the claims of patients whose pleural lesions have developed as a result of constant washing of work clothes contaminated with asbestos, or even as a result of a single contact with asbestos at the workplace, are satisfied.

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