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Mesothelioma: symptoms, prevention, causes, diagnosis and new treatment

Malignant mesothelioma is a rare cancer that affects men most frequently and is primarily associated with asbestos exposure.

Last updated: February 15, 2021 Time taken to read: 12 minutes




What's this thing?


It is called a mesothelioma tumor that arises from mesothelium cells. Mesothelium is a tissue that covers the surface of the serous membranes that "line" the inner wall of the chest, abdomen, and space around the heart like a thin film.

Mesothelium also covers most internal organs and protects them besides producing a particular lubricating liquid that facilitates movement.

Mesothelium seems to have different names depending on the area it covers: it is called pleura in the chest, peritoneum in the abdomen, and pericardium in the space around the heart.

Mesothelioma can originate in four areas of the body: the chest, the abdomen and, very rarely, the cardiovascular cavity and the membrane that lines the testicles.

Benign tumors could also arise from mesothelioma (adenomatoid tumors, benign cystic mesothelioma, etc.) which are generally surgically removed and do not require further treatment.

How widespread it is


Malignant mesothelioma is a rare cancer that affects men more frequently and accounts for 0.4% of all cancers diagnosed in men in Italy and 0.2% of those diagnosed in women in Italy. According to the Italian Cancer Registry Association (AIRTUM), an estimated 1,500 cases between men and 400 cases among women have also been confirmed in 2017.The number of cases among women is slightly increasing, probably because the number of female workers employed in the industrial production of asbestos-containing materials or asbestos, the main cause of this cancer, has increased in recent years.

In the different regions of Italy, there are enormous differences in the number of cases of mesothelioma, as this tumor is mainly associated with exposure to asbestos: in the province of Alessandria, where an important industry was involved in the production of asbestos materials, the incidence is above the national average, with 16 cases per 100,000 for males and 13 cases per 100,000 for females.

Mesothelioma is rare before the age of 50 and has a maximum peak of around 70 years; 5 years post-diagnosis survival in the age group between 45 and 54 years of age stops just below 20% and gradually decreases with increasing age.

Who's at Risk


Exposure to asbestos is the main risk factor for mesothelioma. Most of these cancers involve people who have come into contact with this substance at the workplace. Environmental exposure to these fibers plays an important role, even if it is difficult to assess them.

The term asbestos refers to a family of minerals quite common in nature, with a fibrous structure that is very resistant to heat. Asbestos is dangerous to health because the fibers that make up it, which are more than a thousand times thinner than human hair, can be inhaled and can damage mesothelial cells, causing pleural cancer in some cases.

If they lodge in the lungs, these small fibers may cause other diseases such as, for example, asbestosis (a kind of scarring in the lung tissue that prevents the organ from spreading correctly) or lung cancer. It is important to remember that it may take up to fifty years between the first exposure to asbestos and the onset of mesothelioma, and that the risk does not decrease once the exposure is completely eliminated, but remains constant throughout life.

There is no threshold below which you can be sure of the impertinence of asbestos. It should be noted, however, that a single fiber cannot cause cancer, but a sufficient "cumulative dose" is needed. With increased exposure, both time and the amount of asbestos inhaled are at higher risk, and thus are very high among people who have been employed in factories for manufacturing or processing of asbestos-containing goods, even though the "dose-cumulative" differs widely between individuals.

Such less common risk factors for mesothelioma are exposure to erionite-like zeolites (physical minerals, asbestos fibers) to chest and abdomen, or thorium dioxide injections (used in medicine up until 1950) and SV40 infection, as stated by several trials.

Finally, the role of mutation in the emergence of pleura-type tumor in the presence of an exposure to asbestos fibers of certain genes (such as BAP1) must also be noted.

Groups Inside


Depending on the body region in which they originate, mesotheliomas are classified into:

Pleural mesothelioma: originates in the thoracic cavity and is the most prevalent form of mesothelioma (approximately 3 out of 4 cases);

Peritoneal mesothelioma: occurs in the abdomen and represents almost all the remaining mesotheliomas after the pleural ones;

Pericardial mesothelioma: occurs and is exceedingly rare in the cavity around the heart;

Vaginal tunica mesothelioma: it occurs and is very unusual from the membrane covering the testicles.

If the type of malignant cell present in the tumor, on the other hand, is taken into account, three types of mesothelioma are distinguished:

Epithelioid: the most common and the one that appears to have a stronger prognosis (60-70% of cases);

Sarcomatoid (or fibrous): 10 to 20% of mesothelioma;

Mixed (or biphasic): 30 to 40 percent of mesotheliomas represent epithelioid areas and sarcomatoid areas.

The Symptoms


Initially, the symptoms of mesothelioma are rather unspecific and are frequently overlooked or interpreted as signs of other diseases which are more common and less severe.

Pressure in the lower back or one side of the chest, shortness of breath, cough, fever, exhaustion, loss of weight, trouble swallowing, muscle weakness can be early symptoms of pleural mesothelioma.

The most frequent symptoms in the case of peritoneal mesothelioma are abdominal pain, weight loss, nausea and vomiting.

Prevention, Prevention


Preventing or otherwise reducing asbestos exposure is the safest way to avoid mesothelioma . Law 257 of 1992 requires that the existence of asbestos be tested in public buildings, such as schools, but all old houses can contain traces of this substance. Subsequent laws passed in 2009 and 2011 include more requirements for the handling of hazardous materials. For the first time, the 2011 legislation also recognised the right of employees exposed to asbestos to be paid for occupational diseases.

It is necessary to contact specialist technicians who will inspect the manufacturing materials and extract the non-compliant pieces when you want to remove asbestos. Relying on the elimination of "do-it-yourself" is an option that should be completely avoided, as you run the risk of contaminating other parts of the house and inhaling harmful fibers with a bad job.

Diagnostic


Mesothelioma is a very rare disease and there is no screening for early diagnosis in people not at risk for this reason.

Some doctors prescribe annual examinations (radiography or CT) in the case of persons exposed to asbestos for occupational purposes or for proximity to polluted areas for shorter or longer periods.

Any changes in the lung structure that may suggest the existence of mesothelioma or lung cancer should be monitored over time. It is still uncertain, however, whether this method will lead to early diagnosis in a useful way. In the United States, studies are evaluating the efficacy of tracking mesothelin, a protein formed by mesothelioma cells that may be an early wake-up call for high-risk people, with measurements.

However, the first step towards a proper diagnosis remains a visit to the GP or a doctor who will ask medical history questions to assess any asbestos toxicity and to examine the presence of fluids around the heart in the abdomen or cavity.

In the case of suspected mesothelioma, a few more basic tests are conducted:

  • Chest x-ray: may reveal anomalies in the chest cavity mesothelium, called the pleura (changes in calcium deposit thickness or presence), or in the lungs.

  • Chest tomography (CT): enables the presence of the tumor to be determined, its exact location and its possible spread to other organs, allowing the surgeon to identify the most effective form of surgery as well. The so-called spiral CT is now used more efficiently, which is quicker compared to the conventional one and allows more accurate pictures of the lung structures to be obtained. It also exposes a lower dose of radiation to the patient and is thus more appropriate for close monitoring of at-risk patients.

  • PET/CT scan: enables cells that are growing faster and that lead to cancer cells to be detected. The images obtained are not as thorough as those of high-resolution CT, but the combination of the two techniques will help doctors understand whether tumors or other lesions are actually mesothelial anomalies and whether the cancer has spread to the lymph nodes or other sections of the body.

  • Magnetic resonance: Accurate images of the body's soft tissues, such as CT, can be obtained without the use of X-rays. It may be helpful to determine the health of the diaphragm, the thin muscular membrane below the lungs required for breathing, and any penetration of the disease into the chest wall in the case of mesothelioma.

  • Biopsy: It is the most effective method for verifying mesothelioma suspicion. In certain cases, samples of fluid are collected with a long, thin needle from the chest (thoracentesis), abdomen (paracentesis) or the space around the heart (pericardiocentesis), and the presence of cancer cells is examined under a microscope. In other instances, however, by inserting a probe fitted with a video camera through a small cut in the skin, it is appropriate to take small portions of tissuemesothelial with a fine needle inserted under the skin. This way, the doctor will see unusual areas and take samples under a microscope that are then examined. Although more invasive, this last procedure allows a higher volume of tissue to be removed and thus enables a more accurate diagnosis. The samples taken with the biopsy can be subjected to immunohistochemistry (to know which proteins are present on the surface of the cell) or genetics to differentiate mesothelioma from other cancer forms with certainty (to identify the genes typically expressed by mesothelioma).

  • Blood tests: typically, they are not used to arrive at a diagnosis, but they may be useful to validate the diagnosis obtained by other methods and, in particular, to monitor the path of the disease during and after treatment. The levels of tumor markers such as osteopontin, soluble mesothelin peptide (SMRP) and fibulin-3, the molecules found in higher concentrations in the case of mesothelioma, are measured in particular.

Production


It is necessary to assess the stage of the cancer, i.e. how extensive the disease is, in determining the type of therapy. For mesothelioma, four stages are defined on the basis of TNM parameters that take into account the severity of the tumor (T), the probable involvement of the lymph nodes (N) and the metastases (M).

The lower the point, the better the chances of effective treatment, as with most cancers, including with mesothelioma. However, when the disease has already reached its initial stages and is already difficult to treat, the diagnosis of this tumor also occurs.

Doctors have several options for treating mesothelioma after all the required studies have been carried out: surgery, radiation and chemotherapy.

The probability of surgical intervention is first and foremost assessed when deciding on the method of treatment. In fact, a resectable tumor, that is, one that can be fully removed by surgery, is more likely than one that can not be completely removed to be healed. 

Step I, II and III mesotheliomas are usually operable, but the probability of eliminating them depends on the subtype, position and general condition of the patient, as well as, of course, on the size of the patient.

The operation can have a curative or palliative effect. In the first case, the goal of the operation is to fully eliminate the tumor that must be well placed, while the tumor has already spread in the case of palliative surgery and the main aim is to avoid or minimize symptoms.

Other procedures are also available, which are less invasive than the actual procedure and can be used for palliative purposes: the removal of fluid from the thoracic cavity (thoracentesis), the abdominal cavity (paracentesis) or around the heart (pericardiocentesis) by means of a long and thin needle can provide relief, for example, but, sadly, it must be repeated regularly because the fluid continues to give relief.

For people undergoing surgery (adjuvant therapy) to kill small groups of cancer cells, radiation therapy can be effective if it is not visible and thus not removed during the procedure. Or it can serve a palliative function, with treatment, to relieve chest pain that does not subside.

Chemotherapy for mesothelioma is based on the use of a single medicinal product, or combinations of medicinal products can help delay the progression of the disease, although it can hardly be permanently cured.

The drug can be given systemically or directly into the thoracic cavity (intrapleurally) or abdominal with an intravenous injection that carries it across the body (intraperitoneally).

This localized administration allows higher doses of chemotherapy to reach the tumor, which is often heated to improve its potency (hyperthermic chemotherapy), thus limiting the side effects to the rest of the body.

If chemotherapy is performed to minimize mass and promote removal prior to surgery, it is referred to as neoadjuvant chemotherapy; if, on the other hand, the drug is offered after surgery, it is referred to as adjuvant chemotherapy, which is normally intended to kill tumor cells that are not visible to the naked eye and to enhance the outcome of the surgery.

For several years, numerous biological drug therapeutic studies have been ongoing, but none of these interventions have yet shown a real significant effect on the survival of treated patients. However, the steady improvement in clinical knowledge regarding this condition opens up exciting new therapeutic perspectives.

The material on this page is not a replacement for the opinion of the doctor.

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