Mesothelioma: Types, Symptoms, Diagnosis, and Treatment

Mesothelioma is a kind of cancer that originates in the lining around the organs. There are different types of mesothelial cancers and some of them will be discussed below.

Additionally, it can occur in any region where there is a mesothelium and there are four significant mesotheliomas depending on the location of the tumor.

• Peritoneal mesothelioma.
• Pleural mesothelioma.
• Pericardial mesothelioma.
• Testicular mesothelioma.

Introduction to Mesothelium

The mesothelium is a single layer of mesothelial cells that covers the major organs of our body. It is derived from the mesodermal embryonic layer.

Depending on the location, the mesothelium is also divided into four regions and these are:

• Pleural mesothelium.
• Pericardial mesothelium.
• Peritoneal mesothelium.
• Tunica vaginalis.

It covers the organs, protects them from abrasion or friction against each other or from accident, and secretes serous fluid that works as a lubricant material.

Causes of Mesothelioma

Though there are different types of mesotheliomas that occur in the body, the main cause of all types of these cancers is ASBESTOS.

Exposure to asbestos which is a mineral present in construction site products results in the damage of cellular machinery which can lead to cell death and chronic exposure results in tumor production.

Almost 70% of the cases of mesothelioma reported are due the exposure to asbestos in the lives of patients. [Ref]

Asbestos does not have immediate effects on the body for the onset of a tumor, rather it takes more than 20 years at least to develop mesothelioma.

Asbestos is present in vinyl floor tiles, textured paints, adhesives, etc. Due to the increased risk of mesothelioma by exposure to asbestos, it was banned entirely in 1989 in the US but it is still in use in different forms. [Ref]

Mechanism of Action of Asbestos

The mechanism of action of asbestos is typically like most other carcinogens. First of all, it causes the destruction or damage to the double bond of DNA which then results in mutations and abnormal functioning of cells. Lastly, it also causes abnormal chromosomal segregation which results in chromosomal aberrations.

Apart from the reactions of asbestos with DNA, it also affects indirectly by generating and accumulating the oxidative reactive species (ROS).

In the case of the lungs, the fibers of asbestos inhaled by the person result in the stiffness of the lungs which continues gradually until the lungs do not expand and contract normally.

In the case of peritoneal mesothelioma, the asbestos fibers get stuck within the peritoneum and remain there for years.

These fibers continuously irritate the cells which become inflamed with time. Years of irritation along with inflammation result in fluid accumulation in the peritoneum which puts pressure on the organs and then causes the beginning of a tumor that can spread from one place to another.

Pleural Mesothelioma

The mesothelioma that occurs in the lining of the lungs is known as pleural mesothelioma and it is the most common form of mesothelioma and probably accounts for 75 to 80% of all types of mesotheliomas.

Due to exposure to asbestos, the fiber gets entrapped in the lungs leading to scarring of the lungs and loss of efficiency of the lungs as well. It affects men more than women.

Symptoms:

• Shortness of breath.
• Pain in the chest.
• Trouble breathing.
• Continuous dry cough.
• Hemoptysis ( blood in coughing).
• Edema at the face and arms.
• Dysphagia
• Lower back aches.
• Fever and sweating at night.
• Wollen lymph nodes under the skin of the chest.
• Fluid in the lungs.
• Weight loss and tiredness.

Diagnosis:

Chest pain alerts the doctor for an X-ray examination which reveals fluid in the lungs in case of asbestos exposure.

For a complete and accurate diagnosis, a biopsy for the detection of cancerous cells is done. Blood tests may be useful to check the biomarkers of lung cancer.

Pericardial Mesothelioma

Pericardial mesothelioma is a rare type of cancer that develops in the lining around the heart and is known as the pericardium.

However, Exposure to asbestos is less likely thought to be the etiology of this disease. This is because only 25% of all the cases of pericardial mesotheliomas had asbestos toxicity while there was not a trace of asbestos in the other 75% of patients with pericardial mesothelioma.

Just like other mesotheliomas, it also occurs in old people 55 years of age, representing the median age for this cancer.

Moreover, the chances of this cancer are only less than 1% in all mesothelioma [Ref]. It affects men more than women.

Symptoms:

• Chest pain.
• High temperature and sweating at night.
• Abnormal heart rhythm (arrhythmia ).
• Dyspnea
• Muttering
• Cough
• Shortness of breath while lying at the back.

Diagnosis:

One of the most important and accurate diagnostic techniques is a biopsy in which the tissue pericardium is removed and checked for cancerous cells.

Apart from this CT scans, MRIs, blood tests, and ECGs can be helpful for diagnostic purposes.

Peritoneal Mesothelioma

One of the rare but aggressive types of mesothelioma is malignant peritoneal mesothelioma which occurs in the peritoneal mesothelium.

Like pleural mesothelioma, it is also caused by exposure to asbestos. Abdominal mesothelioma or mesothelioma of the stomach are the two other names for peritoneal mesothelioma. The ratio of cancer is equal in both men and women.

Symptoms :

• Abdominal aches.
• Nausea
• Vomiting
• Constipation
• Diarrhea
• Fever along with sweating at night.
• Swelling of the abdomen which is also known as ascites occurs in this.
• Anorexia with weight loss is common among all types of mesotheliomas.

Diagnostic techniques:

A biopsy of the peritoneum is done to detect it alongside blood tests and imaging scans which are also useful.

Treatment of Mesothelioma

• Surgery:

Surgery can only be performed when the cancer is diagnosed at the initial stage. After that, the tumor mass is resected from the body, and by removing the cancerous mass, so, one can live longer than expected. Lastly, it is done with chemotherapy.

• Chemotherapy:

Some drugs (which are known as chemotherapeutic drugs) are used to treat mesothelioma and these drugs normally either kill the fast-growing cells or stop them from spreading.

Furthermore,  such drugs are mostly used either with surgery or when the surgery is impossible and the use of these drugs has increased the life span of patients as well.

• Radiation:

In this method, radiations from the outside source are targeted at the cancerous cells which destroy them by interacting with their nuclear material.

So, one of the most important advantages of it over other treatments is that it decreases the recurrence of cancer.

However, radiation therapy is not fruitful in the case of pleural mesothelioma but it can decrease the painful condition.

• Immunotherapy:

It is the procedure in which WBCs and other lymph tissues are injected to boost the immune system. Sometimes antibodies are used against the stimulus to limit the growth of tumor cells.

Some drugs are available that boost the immune system in a way that recognizes and kills the cancer cells more effectively.