Mesothelioma and Pleural Mesothelioma in Asbestosis: Diagnosis, Prognosis, and Treatment of Malignant Tumors

The mesothelium is a specialized layer of tissue that lines various organs and cavities in the body. By far the most commonly affected area is the pleura—this is referred to as pleural mesothelioma. Mesothelioma develops much less frequently in other areas, such as the pericardium.

The pleura is covered by a film of fluid. This fluid ensures that the lungs move smoothly within the chest cavity during breathing. If certain cells of the pleura—known as mesothelial cells—become cancerous, pleural mesothelioma can develop.

The degeneration of pleural cells is primarily caused by contact with asbestos (asbestos exposure). People who have been exposed to asbestos in the workplace have a risk of developing this cancer that is approximately a thousand times higher.

There is usually a latency period of 30 to 50 years between asbestos exposure and the development of cancer. For this reason, those affected are usually over 50 years old.

Pleural mesothelioma is rare overall. In Germany, approximately 1,600 people are newly diagnosed with it each year. Men are affected on average four times more often than women.

The clinical presentation is very nonspecific at first. As a result, three to six months often pass between the onset of the first symptoms and the diagnosis.

Pleural mesothelioma typically presents with the following symptoms:

• Shortness of breath, especially during exertion (approximately 90 percent of cases)
• Cough or dry, irritating cough
• Dull chest pain that is difficult to localize
• Fatigue, tiredness, and weight loss (approximately 15 percent of cases)

In addition, about 30 percent of those affected experience recurrent pleural effusions. These are accumulations of fluid in the pleura that are difficult to treat.

In advanced stages, the following often occur:

• coughing up blood (hemoptysis),
• difficulty swallowing (dysphagia),
• hoarseness, and
• so-called Horner’s syndrome

.

Horner’s syndrome describes nerve damage characterized by the three symptoms

• a drooping eyelid,
• a marked narrowing of the pupil, and
• a sunken eyeball

.

Occupational history and evidence of asbestos exposure play a decisive role in the diagnosis. The physician must therefore know whether and when the patient may have been exposed to asbestos.

During the physical examination, the following are usually observed:

• diminished breath sounds as well as
• a muffled percussion sound when tapping the lungs with the fingers.

In advanced stages, there may also be

• a pain-induced compensatory posture,
• palpable masses,
• an asymmetrical chest cavity (thorax),
• restricted or absent movement of the chest during inhalation and exhalation, as well as
• enlarged lymph nodes in the area of the collarbone

may be observed.

In addition, various imaging and other diagnostic procedures are used to better assess the tumor:

• Chest X-ray: A conventional X-ray shows whether there is a pleural effusion and whether the tumor is diffuse or nodular. The latter is significant for the prognosis, as diffuse tumors are more likely to spread to other organs (metastasis).
• Computed tomography (CT): A chest CT scan is used to better assess the tumor and its extent.
• Magnetic Resonance Imaging (MRI): If the findings are unclear, a magnetic resonance imaging scan may also be performed.
• Ultrasound (sonography): A procedure known as pleural sonography can visualize even small pleural effusions. Ultrasound imaging can also be used to assess the extent of the tumor and its invasion into adjacent chest wall structures, such as the diaphragm or the abdomen.
• Pleural puncture: A pleural puncture is used to obtain cellular material from a pleural effusion, which is then tested for the presence of cancer cells.
• Thoracoscopy: A tissue sample is taken during a thoracoscopy. Since the procedure is performed under direct visualization, suspicious areas can be specifically targeted for sampling and examination.

Surgical removal of the tumor as part of a so-called radical operation is the only curative treatment option. Only this procedure can lead to a cure.

This involves removing the pleura and the entire lung (extrapleural pleuropneumonectomy). If necessary, the pericardium and diaphragm may also need to be removed in addition to the pleura and lung (P3D surgery).

In addition, a combination of chemotherapy drugs is generally administered either during or after surgery. These include, among others, 

• carboplatin and paclitaxel,
• cisplatin, and
• permetrexed.

When used in combination, these drugs can significantly improve quality of life and survival rates.

In addition, radiation therapy is administered to the affected half of the chest cavity and the connective tissue space in the center of the chest cavity (mediastinum) to control the tumor locally.

Possible new therapeutic approaches are currently being

• gene therapy approaches,
• photodynamic therapy,
• immunotherapy, and
• the use of so-called VEGF inhibitors

as part of clinical trials.

For most patients, the cancerous tumor is inoperable. For these patients, therefore, only palliative and symptomatic treatment is possible. This means that the cancer is incurable, but treatment improves the patient’s quality of life.

In cases of severe symptoms, chemotherapy may be appropriate in individual cases. According to studies, chemotherapy can

• in 79 percent of cases, pain,
• cough in 67 percent of cases, and
• breathing difficulties in 54 percent of cases

can be reduced.

Before prescribing chemotherapy drugs, the doctor always weighs the benefits against the potential side effects, taking into account

• the patient’s age and general health,
• additional comorbidities,
• the current symptoms, and
• tumor progression

.

Local radiation therapy or partial removal of the pleura can also help alleviate pain and breathing difficulties.

In cases of recurrent effusions, a procedure known as pleurodesis may also be beneficial. In this procedure, the pleural layers are fused together by the doctor introducing talcum powder into the pleural cavity. In some cases, patients in the terminal stage of the disease may benefit from permanent drainage of the effusion fluid via a drainage tube.

The prognosis for pleural mesothelioma is extremely poor. The 5-year survival rate ranges from five to ten percent. The average survival time is approximately one year after diagnosis.

Most patients die as a result of lung failure (respiratory insufficiency). The primary reason for this poor prognosis is late diagnosis. Individuals at occupational risk should therefore undergo screening for early detection.