Mesothelioma

Mesothelioma is recognized as a notifiable occupational disease. If you suspect that asbestos is the possible cause of your illness, you should contact your employer’s accident insurance (SUVA), even if you have already retired.

What is mesothelioma?

Asbestos has been banned in Switzerland since 1990. Due to the long latency period between exposure and the onset of the disease (on average 20 – 40 years), a higher incidence can be observed around 2020. Exposure to asbestos can also cause other cancers such as lung cancer, laryngeal cancer and ovarian cancer. A genetic component is also suspected in a few cases. This is due to a so-called BAP1 mutation, which is associated with the occurrence of other types of cancer (e.g. skin cancer or renal cell cancer) in combination with malignant pleural mesothelioma.

Malignant pleural mesothelioma

The pleura consists of two wafer-thin sheets, the pleura (lining the chest wall from the “inside”) and the pleura (thin membrane that covers the lungs). The two “leaves” cannot be distinguished from each other with the naked eye and are connected by a pleural gap. The pleural cavity is lined with a film of fluid and “glues” the two leaves together through a so-called negative pressure, thus significantly supporting the lungs in expanding.

Men are four times more likely to be affected by MPM than women. At the time of diagnosis, almost 40 percent of patients are between 50 and 69 years old. Around 60 percent are aged 70 and over. The disease rarely affects people under the age of 50. Occasionally, mesothelioma can also occur in the peritoneum.

Occupational risk factor

Asbestos fibers were usually inhaled at the workplace. Protective measures did not exist in the past. In some cases, even the protective clothing contained asbestos.

In addition to occupational exposure to asbestos, there are other risk factors:

• Proximity to asbestos processing factories
• Private contact with asbestos-containing materials (DIY work)
• Staying in areas with natural asbestos deposits
• Improper renovation of building components containing asbestos in old buildings (e.g. old farms)

Symptoms: Mesothelioma causes non-specific symptoms

Pleural mesothelioma can affect the entire pleura and also spread to neighboring organs such as the lungs or diaphragm. In the early stages, the disease is often asymptomatic. The main symptoms are non-specific. Therefore, a lot of time often passes between the first symptoms and the clinical diagnosis.

Symptoms of malignant pleural mesothelioma

• Localized pain in the chest
• Shortness of breath (see below)
• Cough
• Ejection
• Night sweats
• Fatigue
• Weight loss

An indicator of mesothelioma in the majority of patients is shortness of breath (dyspnea) due to pleural effusion. This leads to an excessive accumulation of fluid in the pleural cavity. Chest pain occurs with increasing organ infestation.

Mesothelioma: Diagnosis with us

If a malignant pleural mesothelioma is suspected, a histological examination by means of a so-called pleural biopsy, i.e. taking samples of tissue for microscopic processing and examination, is required. In addition, various imaging procedures (conventional X-ray, computer tomography and positron emission tomography (PET/CT)) are used.

The safest way to obtain a biopsy is via thoracoscopy. Using the so-called “keyhole technique” (minimally invasive), a camera is inserted into the chest cavity and pieces of tissue are removed from the pleura with forceps for histological examination.

The diagnosis of pleural mesothelioma is often very difficult and it can happen that it is wrongly assumed that there is no mesothelioma.

Classification of the stages of disease in mesothelioma

Malignant pleural mesothelioma is mainly divided into three subtypes based on the cell type:

• the epithelioid type
• the biphasic type
• the sarcomatoid type

The epithelioid type is associated with a better prognosis than the other types and, in favorable cases, can result in several years of survival.

As with many cancers, mesothelioma is staged according to the TNM classification. This is a common method for classifying malignant tumors.

Mesothelioma: Treatment in designated centers

The type of treatment depends on how far the malignant pleural mesothelioma has already spread. Malignant pleural mesothelioma should be treated in specialized hospitals, such as the USZ, which have experience in dealing with this rare disease. We also consist of an interdisciplinary team that has worked together for many years. Patients suffering from malignant pleural mesothelioma are discussed at our weekly interdisciplinary tumour board and an individualized treatment concept is determined. Depending on the stage of the disease, the benefits for the person affected must be weighed against the burden of treatment. Diffuse, extensive growth is a major challenge.

Various therapy options are available for treatment:

• Surgical intervention
• systemic therapy
• Radiotherapy
• multimodal concepts

The so-called “multimodal therapy concept” has proven to be the “therapy of choice”, if feasible. The therapy consists of a combination of initial chemotherapy, followed by surgery and, in some cases, further treatment (radiotherapy/chemotherapy). The prerequisite for this is that the tumor is not yet so advanced that it is still operable. In the case of surgery, there are various approaches that are the most common:

• (E)PD: (extended) plerectomy/decortication
• P/D: Pleurectomy/decortication
• EPP: Extrapleural pleuropneumonectomy

These procedures are performed to achieve a macroscopically complete resection, i.e. any visible tumor is removed. This can be achieved with a lung-preserving, extended pleurectomy/decortication (P/D) or an extrapleural pneumonectomy (EPP). For the time being, there is no scientifically sound answer to the question of whether EPP or P/D is the more suitable surgical procedure for MPM, although in recent years there has been a clear trend towards the lung-preserving variant ((E)PD or P/D).

However, a lung-preserving procedure (P/D) is promising if a macroscopically complete resection can be achieved; however, this seems to be more possible in the early tumor stages. In cases of extensive, infiltrative growth into the lung parenchyma, complete macroscopic resection appears to be possible only in the form of an EPP. However, the situation is clearer for patients with impaired heart or lung function, reduced general condition or relevant concomitant diseases. In this case, P/D is certainly the more suitable operation, especially in the early stages of the disease, in order to preserve lung function.

In P/D, a distinction is made between an extended P/D (removal of the pleura from the chest wall and lungs + resection of the diaphragm and/or pericardium), a P/D (removal of the pleura from the chest wall and lungs without resection of the diaphragm and pericardium) and a partial pleurectomy (partial removal of the pleura of the chest wall and/or lungs, leaving a large part of the tumor behind). In EPP, the pleura, a complete lung, the pericardium (heart sac) and the diaphragm (diaphragm) are removed.

Both procedures – EPP and P/D – take five to eight hours and are very demanding operations that should only be performed at centers with the appropriate experience and expertise for the entire peri- and postoperative management.

If inoperable, new therapies such as immunotherapies should be used in the first line, as well as chemotherapy. Participation in a clinical trial is recommended if possible and is often offered in specialized centers.