Mesothelioma

Mesothelioma can mainly be classified by its location and by its tissue type. It most often develops in the pleura. It develops less often in the peritoneum. Much rarer sites are the pericardium and the tunica vaginalis testis. The latter is the covering of the testicle. These rare forms are also important. They are often detected late and can be harder to diagnose because of their unusual location. Regardless of location, doctors also classify mesothelioma by tissue type. These types include epithelioid, sarcomatoid and biphasic mesothelioma. This classification is especially important for treatment planning and prognosis.

Pleural mesothelioma is the most common type of mesothelioma. It develops in the pleura, also called the lining of the lung. The pleura is a thin, double-layered serous membrane. It surrounds the lungs and lines the chest cavity. A close link with asbestos exposure is especially typical. Inhaled asbestos fibers can remain in tissue for a long time. They can trigger chronic inflammation, cell damage and genetic changes. Over time, this can contribute to malignant cell transformation. For this reason, a long latency period is typical. This means many years can pass between asbestos contact and the onset of disease. Pleural mesothelioma usually grows along the pleura. Over time, it can increasingly restrict the lung. This often causes symptoms such as shortness of breath, chest pain or pleural effusions. While lung cancer develops from lung tissue itself, pleural mesothelioma starts in the pleura.

Peritoneal mesothelioma develops in the peritoneum. It is much less common than pleural mesothelioma. Because of its location, this form causes symptoms in the abdomen. Typical signs include ascites, an increasing abdominal size, pressure, bloating or non-specific digestive symptoms. Asbestos is also an important risk factor for peritoneal mesothelioma. However, the exact mechanisms of tumor development are not fully understood in all cases. One important difference from the pleural form is treatment. In some situations, cytoreductive surgery may be used together with intraperitoneal treatment approaches.

In most cases, mesothelioma develops because mesothelial cells have been damaged over many years. Exposure to asbestos fibers plays a key role. It is considered the most important and best documented risk factor. When these fibers enter the body, they can remain in tissue for many years. There, they can trigger chronic inflammation, oxidative cell damage, problems with cell division and genetic changes. Because many years often pass between exposure and disease, mesothelioma is usually diagnosed long after contact with the original trigger.

The most important known risk factors include:

• Asbestos exposure
• Fibrous minerals, such as erionite
• Genetic predisposition, especially an association with BAP1
• Ionizing radiation
• Rare occupational or environmental exposures

The long-term damage of mesothelial cells by fibrous particles is especially important. This mainly refers to asbestos. This connection remains the best documented cause. It also explains a large share of cases, especially in pleural mesothelioma. Occupational exposure is important. Long-term lower-level or indirect exposure can also matter.

Besides asbestos, other fibrous minerals such as erionite are described as rare but relevant triggers. Genetic factors can also increase susceptibility. This is especially true in connection with BAP1 tumor predisposition syndrome. In addition, researchers discuss whether ionizing radiation may contribute to mesothelioma in individual cases.

It is important to know that not everyone with asbestos contact will develop mesothelioma. Still, asbestos remains a central risk factor. A detailed medical history is therefore an important part of diagnosis. This includes occupational, environmental and family history.

Mesothelioma symptoms mainly depend on the location of the tumor. All forms of mesothelioma often cause few or rather non-specific symptoms at first. For this reason, the disease is often detected at a more advanced stage.

In pleural mesothelioma, the main symptoms are often:

• Shortness of breath
• Pleural effusion
• Chest pain
• Persistent cough
• Painful breathing
• Pressure or tightness in the chest

Because pleural mesothelioma grows along the pleura, it can increasingly displace the lung. These symptoms usually appear only when the tumor has already become larger.

Peritoneal mesothelioma causes symptoms that affect the abdomen:

• Abdominal pain
• Increase in abdominal size
• Ascites
• Nausea
• Vomiting
• Constipation
• Loss of appetite
• Pressure or bloating

Mesotheliomas of the pericardium or the tunica vaginalis testis are much rarer. Pericardial mesothelioma may cause shortness of breath, chest pain, cough, fatigue or peripheral edema. Mesothelioma of the tunica vaginalis testis is often noticed because of a hydrocele. It may also cause painless swelling or a palpable change in the testicular area. These rare locations are especially challenging in diagnosis. Their symptoms do not usually point directly to mesothelioma.

General symptoms can also occur, regardless of location. These mainly include:

• Unintentional weight loss
• Reduced appetite
• Tiredness or reduced performance
• General exhaustion
• Gradual physical decline
• Sometimes night sweats

New and persistent symptoms should therefore be taken seriously as possible warning signs. These include increasing shortness of breath, chest pain, repeated pleural effusions or a persistent cough. In peritoneal mesothelioma, increasing abdominal size, ascites, persistent abdominal symptoms, bloating and unexplained weight loss can be important clues.

Mesothelioma is usually diagnosed step by step. Diagnosis combines a detailed medical history, imaging, histological examination and tissue confirmation. Doctors often suspect mesothelioma when symptoms persist. These may include ongoing shortness of breath, pleural effusions or chest pain. In peritoneal mesothelioma, ascites and unclear abdominal symptoms can raise suspicion. Mesothelioma spreads along serous membranes. Early symptoms can therefore be non-specific. A single examination is usually not enough.

Imaging is important for the diagnosis of mesothelioma. In pleural mesothelioma, doctors usually perform a chest X-ray and a CT scan of the chest. These can help assess pleural effusions, pleural thickening, deposits and the local spread of the tumor. MRI or PET-CT may also be useful. They can help with staging or show whether the tumor has spread into the diaphragm, chest wall or neighboring structures. In peritoneal mesothelioma, a CT scan of the abdomen is especially important.

If a pleural effusion or ascites is present, fluid can be removed and examined. However, this test is usually not enough to confirm the diagnosis. A biopsy is therefore needed. The final diagnosis of mesothelioma is made by tissue examination and immunohistochemistry. This confirms the presence of mesothelioma. It also determines the histological type. This means whether the tumor is epithelioid, sarcomatoid or biphasic. This exact classification is especially important for treatment planning and prognosis.

Mesothelioma treatment aims to slow tumor growth and relieve symptoms. The choice of treatment depends on several factors. These include the tumor location, histological type, stage, general health and whether surgery is possible. Treatment is therefore usually planned by several specialists. These may include thoracic surgery, oncology, radiation oncology, radiology and pathology.

In pleural mesothelioma, systemic therapies, surgery and sometimes radiation therapy may be used. The choice depends on the stage and treatment options. In recent years, immunotherapies have become increasingly important. Surgery is not always useful. It is mainly considered when the tumor is localized and judged to be operable. Treatment for pleural mesothelioma is therefore often multimodal.

In peritoneal mesothelioma, cytoreductive surgery can be useful in selected cases. The aim is to remove the tumor sites as completely as possible. This method is often combined with HIPEC. HIPEC stands for hyperthermic intraperitoneal chemotherapy. During this treatment, the abdominal cavity is rinsed with a heated chemotherapy solution directly after tumor removal. This can treat microscopic remaining tumor cells locally.

In addition to standard oncological treatment, supportive complementary measures are increasingly used today. They aim to relieve symptoms and improve quality of life. Studies suggest that acupuncture may have a positive effect on symptoms in thoracic tumors, including mesothelioma. These symptoms may include shortness of breath, pain or treatment-related stress. Mistletoe therapy is also often used in integrative oncology. It is mainly used to support fatigue, general well-being and quality of life. Local hyperthermia is also being studied. Targeted heat treatments may support the effects of chemotherapy or radiation therapy.

Local hyperthermia is also gaining attention as a supportive physical treatment. Both local and systemic approaches may be used. Because mesothelioma often grows regionally in the chest, local hyperthermia aims to improve blood flow in the affected tissue. It may also make tumor cells more sensitive to accompanying chemotherapy or radiation therapy. Mild whole-body hyperthermia may also be used as a supportive measure. It aims to gently stimulate the body’s own immune response. This combined approach is intended to support conventional medical treatment. It may also help maintain quality of life.

Mesothelioma life expectancy depends mainly on the tumor stage, subtype and general health. Because the disease is often detected late, the overall prognosis is unfavorable. More favorable courses are mainly seen in early diagnosed mesotheliomas, localized tumors and the epithelioid subtype. Modern multimodal treatment concepts and immunotherapies have improved treatment options in recent years. Alongside tumor-specific treatment, early palliative care also plays an important role. It can help relieve symptoms and maintain quality of life.

The information listed contains relevant topics and serves to improve understanding.