What Is Pleural Mesothelioma?

Pleural mesothelioma (pleuralmesothelioma) is a primary tumor derived from pleural mesothelial cells, accounting for 5% of pleural tumors, which is rare in clinical practice. Pleural mesothelioma can occur in any part of visceral pleura and parietal pleura. 80% of pleural mesothelioma occurs in visceral pleura and 20% of parietal pleura. It can occur at any age, and is usually 40 to 60 years old. The rate has an upward trend.

Pleural mesothelioma (pleuralmesothelioma) is a primary tumor derived from pleural mesothelial cells, accounting for 5% of pleural tumors, which is rare in clinical practice. Pleural mesothelioma can occur in any part of visceral pleura and parietal pleura. 80% of pleural mesothelioma occurs in visceral pleura and 20% of parietal pleura. It can occur at any age, and is usually 40 to 60 years old. The rate has an upward trend.

Chinese name

Pleural mesothelioma

Foreign name

pleuralmesothelioma

Causes and common diseases of pleural mesothelioma

Pleural mesothelioma is a tumor caused by environmental, biological, and genetic factors. Asbestos has been identified as a carcinogen by the International Cancer Research Centre (IARC). Asbestos is considered to be the leading cause of malignant mesothelioma in the United States and Western countries. Asbestos refers to a group of natural hydrated silicic mineral fibers, which mainly include two forms: serpentine asbestos (chrysotile) and amphibole. The risk of developing mesothelioma depends on the exposure of different types of asbestos mineral fibers. The diagnosis of mesothelioma can be directly attributed to occupational asbestos exposure. However, there is evidence that mesothelioma may originate from sub-occupational exposures (for example, women cleaning their husband's work clothes) and occupational unrelated environmental exposures. Idiopathic or spontaneous mesothelioma can occur in animals and humans who have not been exposed to asbestos. A recent comment indicates that the incidence of spontaneous mesothelioma in humans is one in one million. Asbestos-induced malignant pleural mesothelioma has an incubation period of 30 to 40 years, and the peak period of onset is 45 years after exposure. Different asbestos types cause different types of malignant pleural mesothelioma. The most commonly used and widely used in industry is chrysotile. Blue asbestos is generally considered the most carcinogenic type of asbestos. Long and thin fibers are considered more dangerous because they can penetrate the lungs to cause multiple injuries, tissue repair and local inflammation. The role of amphibole in the pathogenesis of malignantmesothelioma (MM) is widely accepted, and whether chrysotile can cause MM is still controversial. Some researchers believe that chrysotile can induce DNA damage and chromosomal abnormalities in mesothelial cells, while others have suggested that chrysotile can not cause MM but MM caused by amphibole contamination by chrysotile. According to statistics, 80% of MM formation in western countries is related to direct or indirect contact with asbestos. Although asbestos is generally considered to be the most common factor for MM formation, asbestos cannot change the phenotype of cultured mesothelial cells, indicating that there may be Other asbestos-related or independent carcinogens cause malignant mesothelioma.

Differential diagnosis of pleural mesothelioma

Pleural mesothelioma is generally well-defined and has few glitches, while peripheral lung cancer masses generally have irregular edges and visible glitches; the former is an obtuse angle with the chest wall when the tumor is small, and the latter is generally an acute angle; Lung cancer is difficult to identify. Observing the angle formed by the mass and the chest wall may be helpful. The acute angle below the obtuse angle is often the manifestation of pleural mesothelioma. Both pleural mesothelioma and extensive pleural metastases can show extensive irregular or nodular thickening of the pleura with pleural effusion, but the latter has rapid pleural effusion, with fewer signs of pleural volume reduction and mediastinal fixation; many pleural metastases The primary foci are not difficult to identify in combination with clinical and laboratory tests. Tuberculous pleurisy pleura often shows localized thickening, a few are nodular thickening, there is no sign of "freezing" in the mediastinum, and the ipsilateral thorax does not become smaller; chest pain generally occurs early, and chest pain disappears when a large amount of pleural effusion is formed However, chest pain of malignant pleural mesothelioma is progressively aggravated, pleural effusion increases and chest pain is not relieved.

Pleural mesothelioma examination

The characteristics of pleural mesothelioma are: (1) Thickening of the pleura is the basic feature of the disease. Benign pleural mesothelioma is mostly limited pleural thickening, and malignant pleural mesothelioma is mostly diffuse pleural thickening. The disease is prone to unilateral invasion, and a few may be bilateral invasion. Pleural thickening can affect both the visceral and parietal pleura, and appears as oval, hump-shaped, nodular, wavy, and ring-shaped thickening. Pleural thickness 1cm has characteristic significance for the diagnosis of this disease. In diffuse pleural thickening, multiple nodular thickening is the most common, and pleural ring thickening is mostly in the middle and late stages. It is a lesion that infiltrates the entire thorax, and the pleura is generally thickened and fixed, showing a "frozen" sign. (2) Most cases have a large amount of pleural effusion. In severe cases, the pleural effusion can occupy the entire thoracic cavity up to the apex of the lung. In some cases, interlobular effusion can be seen. A few patients can invade the pericardium and cause pericardial effusion. (3) "Frozen" sign, that is, the tumor infiltrating the mediastinum causes the mediastinum to be fixed, and the volume of the affected thorax is reduced. The pleura is widely thickened, and the intercostal space is narrowed due to a large amount of pleural effusion, which is common in patients with diffuse pleural thickening. (4) Other manifestations: bone destruction can be seen in tumor-infiltrated ribs; pleural plaques and pleural calcifications can occur in those with asbestos exposure history; lymphatic metastasis can cause mediastinal and hilar lymphadenopathy. (5) CT enhancement features: Thickened pleura is generally significantly strengthened, cystic changes and necrosis can occur when large lumps are formed, and the enhancement scan is unevenly enhanced. Enhanced scanning has obvious advantages in clarifying the pleural thickening, the shape, scope, blood supply, surrounding invasion, and lymphadenopathy of pleural thickening.

Principles of pleural mesothelioma treatment

Malignant pleural mesothelioma is a disease with a high degree of malignancy. When diagnosed, it usually reaches stage III to IV, and local treatments such as surgery and radiation therapy are difficult to achieve. Therefore, the treatment of malignant pleural mesothelioma is still mainly medical, but its efficacy and survival are limited, mainly for the purpose of palliative symptomatic treatment. In recent years, with the advent of third-generation chemotherapy drugs and targeted drugs, it has brought new opportunities for the treatment of malignant pleural mesothelioma.

Antimetabolites are one of the most effective drugs for malignant mesothelioma. In a phase II clinical study, high-dose methotrexate treatment with 60 patients was able to achieve a 37% response rate and median survival of 11 months. The response rate of another antifolate drug, idatrafloxacin, is 16% to 25%, and the median survival time is 6.6 to 9.6 months. It is worth noting that the drug combined with folinic acid (formyltetrahydrofolate) can make toxicity Decreased, but at the same time reduced the rate of remission.

Gemcitabine is an anti-metabolic drug. The response rate of malignant pleural mesothelioma as a single drug is 0 to 31%. However, the results of combining gemcitabine and cisplatin are better. Some scholars have used gemcitabine (1000mg / m2, d1, d8, d15) combined with cisplatin (100mg / m2, d1) for 28 days to treat 21 patients. The survival time was 9.4 months, the one-year survival rate was 41%, and 90% of patients had reduced disease-related symptoms. Another multi-center study involving 52 patients also used the 28-day gemcitabine plus cisplatin regimen, with a partial response rate of 33% and a median survival of 11.2 months. In addition, the response rate of gemcitabine combined with carboplatin in 26 patients was 26%, and the median survival was 15.1 months. The response rate of gemcitabine combined with oxaliplatin was 40% in 25 patients, and the median survival was 13.0 months. The above results suggest that gemcitabine combined with platinum is an ideal combination for malignant pleural mesothelioma.