Pleural cancer is a malignant tumor of the parietal or visceral leaf of the serous lining of the lungs. Disease is characterized by rapid progression: early onset of pain, accumulation of exudate in the pleural cavity, increasing shortness of breath. For the detection and histological confirmation of pleural cancer, X-ray examination, ultrasound of the pleural cavity, diagnostic puncture, pleural biopsy, precalescent biopsy, thoracoscopy, cytological examination of pleural effusion, morphological analysis of the biopsy is performed. Treatment requires a pleurectomy or pleuropulmonectomy, supplemented by radiation therapy and chemotherapy.
Malignant tumors affecting the pleura, by their origin, can be primary and secondary. Primary malignant lesions of the pleura in pulmonology include mesothelial tumors, with a predominance of fibrous (pleural sarcoma) or epithelial component (pleural cancer). In some cases, there are tumors of mixed structure containing elements of sarcoma and cancer (sarcocarcinoma). According to the type of growth, primary pleural cancer is divided into localized and diffuse. Histologically, disease is represented by various variants of mesothelioma. Primary form accounts for 0.3% in the structure of all oncopathology; it occurs with the same frequency in men and women.
Secondary form has a metastatic character. Most often, lung, ovarian, breast, and thyroid cancers metastasize to the pleura.
Causes of pleural cancer
It has been established that more than 70% of cases of pleural cancer are etiologically associated with inhalation of asbestos dust. Contact with such varieties of asbestos as crocidolite, chrysolite and amosite is considered especially harmful. Pathology can develop 30-40 years after contact with asbestos, therefore, despite the serious legal restrictions on the use of asbestos in force today, pleural mesotheliomas still occur due to the influence of this production factor. The risk category includes persons employed in the mining, construction, textile industry, shipbuilding.
Asbestos dust can also cause pneumoconiosis (asbestos), asbestos pleurisy, plaques on the pleura, pleural fibrosis, lung cancer, laryngeal cancer, peritoneal mesothelioma. In addition to exposure to asbestos, the importance of other harmful factors, especially smoking, is considered among the causes of this disease.
The diffuse growth of mesothelioma occurring in most cases causes its spread through the pleura and lymphatic pathways with the formation of multiple nodes thickening the pleural leaves. Diffuse pleural cancer affects the visceral and parietal leaves early, causing their fusion and obliteration of the pleural cavity over an extended area. In the absence of obliteration, serous pleurisy develops in the pleural cavity – serous exudate accumulates, which, as a result of desquamation of the epithelium and damage to small vessels, quickly acquires a hemorrhagic character. When pleural cancer spreads through the interstitial crevices, the intra-thoracic fascia, ribs and intercostal muscles, esophagus, vertebrae, peritoneum are involved in the process.
Classification of pleural cancer, according to the TNM system, provides for the allocation of stages:
- Tx – T0 – absence of signs of primary pleural cancer
- T1 – the prevalence of the tumor is limited to the parietal pleura
- T2 – lesion of the parietal, diaphragmatic, mediastinal and visceral pleura, germination of pleural cancer into the lung or diaphragm
- TK – the germination of pleural cancer into the ribs, intra-thoracic fascia, pericardium, chest wall muscles, mediastinal tissue, mediastinal organs
- T4 – the spread of pleural cancer to the pleura and lungs from the opposite side, peritoneum, abdominal organs, neck tissue, spine. Pleural cancer is inoperable.
- Nx – N0 – lack of data for regional metastases
- N1 – metastasis to the peribronchial nodes or lymph nodes of the lung root on the side corresponding to the lesion
- N2 – metastasis to mediastinal lymph nodes and tracheal bifurcation on the side corresponding to the lesion
- N3 – metastasis to lymph nodes (mediastinum, lung root, subclavian, etc.) from the opposite side.
- Mx – M0 – lack of data for distant metastases of pleural cancer
- Ml – detection of distant metastases in various organs.
Pleural cancer symptoms
Pleural cancer has a rapid course and usually leads to death within a few months.
Early clinical manifestations are pain on the affected side of the chest when breathing, dry cough, subfebrility. The pains have a persistent aching, often painful nature, can radiate into the upper arm, shoulder blade. When the thoracic sympathetic chain is compressed, Gorner’s syndrome develops (ptosis, miosis, enophthalmos, weak pupil reaction to light, dyshydrosis).
Pathology proceeds with a rapid and constant accumulation of exudate in the pleural cavity, which leads to an increase in shortness of breath. With thoracocentesis, a dense thickened pleura is felt; the exudate has a hemorrhagic character and after removal it quickly accumulates again. Cytological analysis of pleural effusion reveals atypical cells in it.
Manifestations due to compression of the mediastinal organs develop, in particular, the syndrome of the superior vena cava. With this disease, general weakness, anemia and cachexia rapidly progress. The clinic of secondary pleural cancer is similar to that of pleural mesothelioma: there are pains on the side of the lesion, accumulation of hemorrhagic exudate, shortness of breath. All these manifestations are aggravated by the symptoms of the primary cancer process.
The detection of pleural cancer is based on the comparison of anamnesis, clinical picture, X-ray, endoscopic, cytological and morphological studies. In case of suspicion of pleural mesothelioma, it is of paramount importance to clarify the professional history, namely, contact with asbestos-containing products.
Lung x-ray reveals a lumpy uneven thickening of the pleura (focal or diffuse), multiple nodes along the periphery of the pulmonary fields. Lung CT (MRI, PET) is used to clarify the localization and prevalence of pleural cancer, detect infiltration of the chest, lung lesions, mediastinal lymph nodes, pericardium, and the opposite lung. X-ray and tomographic examination is carried out after preliminary pleural puncture and maximum evacuation of exudate.
During ultrasound of the pleural cavity, pleural effusion is detected, and in its absence, a tubercle-like thickening of the pleura. Diagnostic pleural puncture and transthoracic puncture biopsy of the pleura are performed under the control of ultrasound. In some cases, cytological examination of pleural effusion and morphological examination of the biopsy can confirm the diagnosis of pleural cancer. Targeted biopsy and visual examination of the pleura is carried out during diagnostic thoracoscopy (pleuroscopy).
Bronchoscopy can be used to exclude bronchial cancer, confirm asbestos intoxication by conducting bronchoalveolar lavage and detecting asbestos particles in flushes from the bronchi. Differential diagnosis of pleural cancer is carried out with tumors of the chest wall, obstructed pleurisy, benign pleural tumors, peripheral lung cancer, metastases of tumors from distant organs.
Treatment for pleural cancer
When the parietal pleura is affected, a pleurectomy is performed, and in the case of a visceral pleura lesion, a pleuropulmonectomy is performed. These types of operations are often combined with resections of the affected organs (diaphragm, pericardium, ribs, etc.), with postoperative chemotherapy and radiation. However, even radical surgery is usually accompanied by short-term treatment success.
In most cases, due to the late diagnosis of pleural cancer and the vastness of the lesion, radical surgery is impossible, therefore, polychemotherapy and radiation therapy are performed. Symptomatic treatment of pleural cancer includes discharge punctures (pleurocentesis), drainage of the pleural cavity, the introduction of cytostatic drugs into the pleural cavity to slow the rate of exudation and stimulate obliteration of the cavity (pleurodesis), anesthesia. Innovative methods of treating disease that have not yet been widely used include gene therapy, photodynamic therapy and immunochemotherapy.
Prognosis and prevention
The outcome of pleural cancer is unfavorable: most patients die within a few months of diagnosis. Early multimodal treatment of disease, including pleuropneumectomy with chemotherapy and postoperative radiation, allows achieving five-year survival in 17-25% of patients.
The main measure for the prevention of pleural mesothelioma is the exclusion of contact with asbestos and the use of alternative materials in the production. Also, the recommendations of pulmonologists include quitting smoking and conducting an annual screening of the population (fluorography).