Pleural mesothelioma is a connective tissue tumor of the mesothelium, a membrane that lines serous body cavities.
The mesothelium is an epithelium that is not supplied with blood (it does not contain blood vessels) that produces a serous, mucus-like fluid and forms the covering tissue of:
- testicles and other organs.
Mesothelioma is mainly caused by prolonged exposure to asbestos fibers.
asbestos causes the inflammation of mesothelial cells; the evolution of this process causes:
- Irreversible scarring, the macrophages stimulate the fibroblasts to produce connective tissue. The result is the formation of interstitial fibrosis.
- The asbestos fibres enter the cell and hinder the functioning of the cell structures, which are fundamental for normal cell division.
- Production of free radicals that damage the DNA of the cell.
- Production of oncoproteins that eliminate the blockade mechanisms of cell proliferation.
As a result, cancer can develop.
People who are directly exposed to asbestos fibers are classified in the high pleural mesothelioma risk groups.
When a person inhales the fine asbestos fibres, they settle in the lungs. Hair and clothing of people who are in direct contact with asbestos pose a danger to others with whom they come into contact.
It has been observed that the development of pleural mesothelioma with serious consequences is about 30-40 years after the first exposure to asbestos.
Types of mesothelioma
Depending on the affected mesothelium, mesotheliomas can be divided into four groups:
- Pleural mesothelioma affects the pleura that covers the lungs: the pleura (especially the inner layer: pleura or pleura visceralis). It is the most common type of mesothelioma and accounts for over 80% of cases.
- Peritoneal mesothelioma is a tumor that affects the coating of the stomach (peritoneum). It is not very common and accounts for 10-20% of cases of mesothelioma.
Peritoneal mesothelioma occurs on the outer walls of the stomach.
- Pericardial mesothelioma affects the pericardium. It is a rare form of mesothelioma (1-5% of cases).
There are few people diagnosed with metothelioma who suffer from this type of tumor.
- Testicular mesothelioma – develops in the testicular protective sheath (tunica vaginalis) and is very rare.
Gutartiges und bösartiges Mesotheliom
Das Mesotheliom kann in zwei Formen auftreten:
Benign: The benign form of mesothelioma is very rare. Examples of benign mesotheliomas are:
- adenomatoid tumor,
- benign, cystic mesothelioma.
Malignant: Is the more common form, a rare but extremely aggressive neoplasia.
Malignant mesothelioma is distinguished by malignant cell type.
Cell types of mesothelioma
1. Epitheloid mesothelioma Epitheloid mesothelioma
is the most common cell type and covers about 50-75% of cases diagnosed in a year. All these cells show a roundish or polygonal shape, which is easily distinguishable under the microscope.
This type of tumor cell is similar to that of adenocarcinoma.
2. Sarcomatous mesothelioma
Sarcomatous mesothelioma is a less common type of cell and occurs in about 7-20% of cases diagnosed each year. These cells are fish-like like those of muscles and bones.
Because of this similarity, it may be difficult to distinguish sarcomatous mesothelioma under the microscope from tumors:
- of the bones (osteosarcoma),
- of connective tissue (fibrosarcoma).
3. Biphasic mesothelioma
Biphasic mesothelioma is formed by both epithelial cell components and sarcomatous components.
It accounts for about 30-40% of mesotheliomas.
Treatment options for mesothelioma do not vary significantly between different cell types, but sarcomatous mesothelioma is often the most difficult to treat due to its spread to surrounding tissues.
Causes of pleural mesothelioma
The main cause of mesothelioma is exposure to asbestos (80% of cases), but only 5% of people exposed to asbestos develop mesothelioma.
This means that exposure to asbestos is not solely responsible for the tumor.
Less common causes of mesothelioma:
- Virus SV40 (not confirmed)
Mesothelioma is not a common form of cancer, but it is not so rare in people exposed to asbestos.
These individuals have a 1000 times higher risk of developing mesothelioma.
The risk doubles if the person exposed to asbestos is also a smoker; Smoking stimulates the macrophages that play an important role in the development of mesothelioma.
Exposure to asbestos may occur:
Direct exposure occurs when the person concerned comes into direct contact with asbestos fibres. For example:
- workers in an asbestos mine,
- Construction worker
- Car scrappers and mechanics dealing with brakes and clutches of vehicles.
Indirect exposure to asbestos is present in the case of:
- indirect contact with asbestos (e.g. people who live in or frequently stay in buildings with asbestos parts, such as pipes, roofs, etc.;
- Contact with people directly exposed to asbestos. For example, family members and friends of people with direct exposure to asbestos who have ingested the asbestos fibers through clothing and hair.
You do not have to be exposed to asbestos fibers for a long time, even short-term exposure could cause mesothelioma.
After asbestos inhalation, mesothelioma is the most common health effect. But it can also develop:
- Asbestosis: formation of scar tissue or pulmonary fibrosis caused by asbestos fibres,
- Lung tumor: the carcinoma develops in the lung tissue.
Mesothelioma is something else and should not be confused with asbestosis and lung tumor.
Symptoms of pleural mesothelioma
Signs and symptoms of pleural mesothelioma may include:
- chest pain (from mild to severe);
- Pleural effusion;
- shortness of breath or dyspnea, first during exercise, then also at rest;
- nodules on the skin and chest;
- persistent cough (from mild to severe);
- Weight loss;
- constant wheezing when breathing;
- Traces of blood in sputum in catarrh.
Symptoms of peritoneal mesothelioma
Signs and symptoms of peritoneal mesothelioma may include:
- constant abdominal pain (from mild to severe);
- abdominal swelling;
- nodules in the abdomen;
- Intestinal obstruction and constipation;
- sudden and unexplained weight loss;
Symptoms of pericardial mesothelioma
Possible symptoms include:
- irregular heartbeat (cardiac arrhythmia),
- chest pain,
- shortness of breath,
- night sweats.
Symptoms of testicular mesothelioma
The leading symptom of testicular mesothelioma is the formation of nodules on the testicles.
In some cases, testicular pain occurs.
Diagnosis of mesothelioma
The diagnosis of mesothelioma is not easy to make because the symptoms are similar to other more common conditions, such as:
- seasonal allergies.
After collecting the patient’s complete medical history, the doctor prescribes other examinations if mesothelioma is suspected.
Imaging examination methods
The best method of detecting mesothelioma is through instrumental examination, for example:
- X-ray horax (X-ray) – the most important examination. In mesothelioma, the X-ray shows a thickening of the mesothelium in the lower (basal) area of the lungs. In advanced stages, thickening spreads to the upper areas of the lungs. Often you can also see a pleural effusion.
- CT – helpful to assess the extent of the disease.
- Magnetic resonance imaging – this examination can be used to determine the severity of mesothelioma.
- Positron emission tomography PET – used for stage determination.
Biopsy and laboratory tests
Another way to determine mesothelioma is to examine a biopsy. This can be done by:
- surgically performed in laparoscopy thoracoscopy for pleural mesothelioma,
- Peritoneoscopy for peritoneal mesothelioma (in laparoscopy).
Treatment of mesothelioma
A definitive cure of mesothelioma is not possible; the therapies should:
- alleviate the symptoms,
- increase the life expectancy of the patient.
The doctor takes into account:
- localization of the tumor,
- State of health of the patient.
The most common therapy for mesothelioma is surgery, followed by:
Depending on the specific case, these types of treatment can be combined.
Those who suffer from this condition should stop smoking, because the smoke from cigarettes can greatly worsen the situation.
Surgical intervention for pleural mesothelioma
Surgeons remove mesothelioma if it was diagnosed at an early stage and is still operable.
Surgery can reduce the signs and symptoms caused by mesothelioma spreading throughout the body.
There are the following surgical options:
- Surgery to reduce fluid retention.
Pleural mesothelioma can cause fluid accumulation (pleural effusion) and thus cause difficulty breathing.
The surgeon inserts a tube or catheter into the chest to drain the fluid. He may also introduce a medication into the chest to prevent recurrence of fluid retention (pleurodesis).
- Surgery to remove the tissue surrounding the lungs or abdomen (pleurectomy). The surgeon removes the pleura and pleura. This procedure can only be performed in 10-15% of patients.
- Surgery to reduce fluid retention.
- Surgical intervention to remove most of the cancerous tissue (debulking or cytoreduction).
If the removal of the entire tumor is not possible, surgeons can try to remove the largest possible part. Debulking allows the doctor to perform more precise chemotherapy or radiotherapy to relieve symptoms.
- Surgical procedure to remove a lung and surrounding tissue (extrapleural pleuropneumonectomy). Removal of the affected lung and surrounding tissue can reduce the discomfort and symptoms of pleural mesothelioma. If radiotherapy of the chest is carried out after this operation, a higher dose of radiation can be used because no lung tissue can be affected by the damaging side effects.
Chemotherapy is performed using chemical substances that kill the tumor cells. Systemic chemotherapy affects the entire body and can reduce or slow the growth of inoperable mesothelioma.
Chemotherapy can also be performed:
- before surgery (neoadjuvant chemotherapy) to facilitate the procedure,
- after surgery (adjuvant chemotherapy) to reduce the possibility of recurrence.
Drugs for chemotherapy can also be warmed up in peritoneal mesothelioma and directly:
- into the abdominal cavity (intraperitoneal chemotherapy)
- or in the case of pleural mesothelioma in the thoracic cavity (intrapleural chemotherapy).
When using this therapy, mesothelioma can be reached directly without harming healthy cells in other parts of the body.
It allows doctors to use high doses of chemotherapeutic drugs.
Radiation therapy involves administering high-energy rays such as X-rays to one or more specific points of the body.
The rays can reduce discomfort and symptoms in people with pleural mesothelioma.
Sometimes radiation therapy is done after biopsy or surgery to prevent the spread of mesothelioma after surgery.
Immunotherapy: vaccination Scientific studies are
currently being carried out on a vaccine against diseases caused by asbestos.
This drug can help the immune system identify the cancer cells.
The vaccination could be useful for blocking tumor growth.
The therapy recognizes and alters the genes responsible for cancer development.
Photodynamic therapy uses the property of light and consists of:
- Administration of a light-activated substance (a so-called photosensitizer), which is absorbed by the tumor cells in increased quantities.
- Laser therapy on mesothelioma to destroy the cells.
Prognosis, survival and life expectancy for patients with pleural mesothelioma
Mesothelioma is not only a very rare tumor, it is also the deadliest tumor.
Survival time after diagnosis (usually 30-40 years after exposure to asbestos) is only 12-18 months or less without therapy/medication.
One of the main factors in survival time is the stage to which the disease has progressed.
Course and development of the disease
One of the typical characteristics of mesothelioma is the latency period (i.e. the time between exposure to asbestos and the onset of the disease), which is about 15 to 40 years.
- Stage I: in the initial phase, mesothelioma is localized on a pleural layer and the tumor may have spread to the pericardium or diaphragm.
The life expectancy of a patient with mesothelioma in the first stage is about 2 years (21 months). Studies show that 50% of patients diagnosed with mesothelioma can survive another five years with forced therapy.
- Stage II: in the second phase, the involvement of both pleural sheets can be observed on only one side of the body. Life expectancy at this stage is about 1-2 years after the diagnosis was made.
- Stage III: in the third phase, the tumor spreads to the chest wall, esophagus and the lymph nodes on one side of the body. Life expectancy at this stage is about 16 months.
- Stage IV (last stage): in the fourth stage (final stage) of mesothelioma, it spreads to other body organs and metastases form in bones, liver, lymph nodes, brain or other areas of the body.
In the fourth stage of mesothelioma, the hope of survival is less than 12 months.