Pleural tumors are found in the pleural—the cavity between the lungs and chest wall that contains lubricating pleural fluid. Pleural cancers can be divided into four subcategories:

• Malignant pleural mesothelioma;
• Solitary fibrous tumour of the pleura;
• Secondary neoplasms (from other cancers);
• Lymphomas.

STAFF

At the IEO pleural tumors are treated by a multidisciplinary team consisting of specialists in:

• Thoracic Cancer Surgery
• Thoracic Oncology
• New Drugs and Early Drug Development for Innovative Therapies
• Department of Pathology and Laboratory Medicine
• Department of Medical Imaging and Radiation Sciences

The main risk factor for mesothelioma is exposure to asbestos. The majority of these cases involve people who have come into contact with this substance in the workplace. (1) Other less common risk factors are exposure to zeolite (minerals with chemical characteristics similar to those of asbestos), radiation to the chest and abdomen or injections of thorium dioxide (used in medicine until 1950) and, according to a few studies, SV40 virus infection.

The solitary fibrous tumor of the pleura is a mostly benign (non-cancerous) overgrowth arising from mesenchymal tissue. No clear-cut risk factors for Solitary Fibrous Tumor of pleura have been established to date.

(1) The main risk factor for mesothelioma is exposure to asbestos. The majority of these tumours involve people who have come into contact with this substance in the workplace. The term asbestos means a family of minerals rather common in nature, with a fibrous structure that is highly resistant to heat. Asbestos is a health hazard because its fibres are over a thousand times thinner than a single human hair and so can be inhaled and cause damage to the mesothelial cells, causing cancer in some cases. If these small fibres are deposited into the lungs, they can cause diseases such as asbestosis (a type of scarring in the lung tissue that prevent the expansion of the organ), or lung cancer. It may take more than 20 years between the first exposure to asbestos and the onset of mesothelioma and the risk does not decrease once the exposure has been completely removed, but remains constant throughout life. There is no threshold beyond which the danger of asbestos is certain. In theory, even a single fibre can cause cancer, but the risks increase with increasing exposure in terms of time and quantity and are therefore very high in people who have worked in factories for the production or manufacturing of articles containing asbestos. The family members of these workers are also at risk, because the asbestos fibres can stick to clothes coming from the workplace to home.

Malignant mesothelioma is a rare cancer that affects men more frequently and in Italy represents 0.4% of all cancers diagnosed in men and 0.2% of those diagnosed in women. This is equivalent to saying that 3.4 cases of mesothelioma occur per 100,000 men and 1.1 per 100,000 women. Mesothelioma is rare before the age of 50 and peaks at around 70 years old; the 5-year survival after diagnosis is just under 20 per cent in the 45-54 age group and progressively decreases with increasing age. From the most recent data, it seems that this cancer in Italian women is slightly but steadily increasing.

Mesothelioma is quite a rare disease and for this reason there are no screening programs for the early diagnosis in persons not at risk. In the case of persons exposed to asbestos for longer or shorter periods, some doctors recommend periodic examinations (X-ray or Computed Tomography) to monitor any changes over time in the structure of the lungs that might indicate the presence of mesothelioma or lung cancer. However it is not yet clear whether this strategy could lead to early diagnosis.

The best way to prevent mesothelioma is to avoid or at least minimise the exposure to asbestos. New laws require the verification of the presence of asbestos in public buildings such as schools, but there may also be traces of this material in older homes. It is important to contact professional technicians who will check construction materials and remove the parts that are not up to standard. DIY removal should be avoided, since bad work may cause the risk of contaminating other areas of the house and the inhalation dangerous fibres.

Symptoms of the malignant pleural mesothelioma

The symptoms of mesothelioma are initially non-specific and they are often ignored or interpreted as signs of other more common and less severe diseases. Early signs of pleural mesothelioma may include pain in the lower back or side of the chest, shortness of breath, cough, fever, fatigue, weight loss, difficulty swallowing, muscle weakness. Abdominal pain, weight loss, nausea and vomiting are more common symptoms of peritoneal mesothelioma.

Test for diagnosing malignant pleural mesothelioma

The first step for a proper diagnosis remains a visit to the general practitioner or a specialist, inquiring about medical history to determine whether there has been exposure to asbestos and assessing the presence of fluid in the abdomen or in the cavity around the heart. In cases of suspected mesothelioma, more specific tests will be carried out. 

• Chest CT with contrast medium is used to determine the presence of the cancer, its exact location and the possible spread to other organs, and assist the surgeon in deciding the type of intervention. A spiral CT has recently been developed that is faster and allows for more detailed images compared to the traditional one.
• PET is used to identify the cells that are growing faster and correspond to cancer cells. The images obtained are not as detailed as those of the TC but may help doctors understand whether the abnormalities of the mesothelium are actually tumours or lesions of other kinds and whether the cancer has spread to lymph nodes or other parts of the body. Today, there are tools that can perform both CT and PET in a single session.
• Biopsy is the most effective tool to confirm a suspected mesothelioma. In some cases  fluid samples are obtained from the chest (thoracentesis), abdomen (paracentesis) or the cavity around the heart (pericardialcentesis) using a long thin needle to ascertain the presence of cancer cells under a microscope. In other cases, it is necessary to withdraw small portions of mesothelial tissue with a thin needle inserted under the skin or with the insertion of a probe equipped with a video camera through a small cut in the skin. This way, the doctor can see the suspicious areas and take the samples to be then analysed under the microscope. To distinguish mesothelioma from other types of tumour with certainty, samples taken by biopsy may be subjected to immune-histochemical assays (to see the proteins present on the surface of the cell) or genetic assays (to detect the expression of genes typical of mesothelioma). Blood tests are not typically used to arrive at diagnosis, but it may be useful to confirm a diagnosis obtained with other techniques or to follow up the evolution of the disease during and after treatment. 

Solitary fibrous tumor of the pleura: symptoms and test for diagnosis

This is a rare, usually benign neoplasm. Solitary fibrous tumour of the pleura is derived from mesenchymal cells in the subpleural connective tissue. This form of cancer affects both serous layers that form the pleura (visceral and parietal); only rarely does it involve the mediastinum, pancreas, neck, nasal sinuses and lungs. Solitary fibrous cancer of the pleura can afflict men and women of every race and age. It has been observed that the majority of these cancers affect people over the age of 60. Solitary fibrous cancer of the pleura has a significantly lower incidence compared to pleural mesothelioma.

This variant of the pleural cancer has a mostly silent course and it is often diagnosed by chance through a simple imaging test. The bigger the mass size the more likely and severe the symptoms are: shortness of breath, chest pain and cough are three recurrent symptoms in patients with pleural fibrous cancer. Less frequently, however, patients suffering from this form of pleural cancer may complain of anorexia, chills, fever, haemoptysis, swelling of the lower limbs, paraneoplastic manifestations (osteoarthropathy and hypoglycaemia by overproduction of the Insulin-like growth factor II), syncope and pleural effusion. In the giant forms hypomobility of the hemithorax affected by the neoplasia may be encountered.

Fibrous cancer of the pleura is often diagnosed by chance via a simple radiological investigation performed for other reasons. Among the diagnostic strategies aimed at ascertaining tumour of the pleura: routine blood tests, upper abdomen ultrasonography, CT scan, chest CT and MRI, are included. A few patients have to undergo a further examination, PET, which is useful in selected subjects with a suspected malignant degeneration of the cancer.

Malignant pleural mesothelioma

There are no guidelines for the treatment of mesothelioma because of the limited number of cases. Therapy is strictly dependent on the stage. For stage I and selected cases in stage II and III the main option is surgery, pleurectomy with decortication or extrapleural pleuropneumonectomy, preceded by induction chemotherapy (before surgery) and possibly post-operative radiotherapy if the patient’s clinical conditions permit.

The surgery also uses talc in a technique practised in video-thoracoscopy using a pleuroscope. The liquid is removed and talc is introduced. Talc creates a local inflammatory reaction and joins the two pleural layers preventing the effusion to be formed again. This technique must be followed by radiotherapy on the thoracoscopy gap in order to limit or avoid a potential seeding of tumour cells that cause the formation of subcutaneous nodules.

Chemotherapy is the treatment of choice in cases not operable with radical technique or after talc has been used. Platinum and its derivatives are used as standard associated with a second drug that may be pemetrexed, gemcitabine or paclitaxel, in combination with or without radiotherapy.

Solitary fibrous tumour of the pleura

There is no standard treatment protocol established for Solitary Fibrous Tumor of Pleura. However, in majority of cases, a complete surgical excision with clear or wide margins is the preferred mode of treatment, which can result in a cure, especially if it behaves in a benign manner. The whole mass should be removed with surgical excision of one or more portions of the parietal/diaphragmatic/mediastinal pleura.