Pleural Mesothelioma | Causes, Symptoms, Diagnosis and Treatment Options for the Pleural Mesothelioma

The Pleural Mesothelioma is the type of cancer that forms down the lining of the lungs when an individual gets continuously exposed to asbestos. Malignant Pleural Mesothelioma (MPM) makes up about 75% of all the mesothelioma cases in record.

Pleural Mesothelioma | Causes, Symptoms, Diagnosis and Treatment Options for the Pleural Mesothelioma
Image credit – asbestos.com

Before we dive into the causes, Symptoms, Diagnosis and Treatment of the Pleural Mesothelioma, let us take a quick look at an overview of what the disease is all about.

Pleural Mesothelioma

The Pleural mesothelioma is a type of mesothelioma cancer which is very rare. It is the type that develops in the Pleura, that is, the thin membrane that lines the lungs and the chest cavity. Whenever there is a lodging of asbestos fibers in the lining of the lungs, they can lead to scaring and inflammation. The tumors themselves that form in the Pleura are what we know as Pleural Mesothelioma.

Some FACTS about the Pleural Mesothelioma are:

  • It is the most common type of mesothelioma amongst all.
  • Pleural mesothelioma is not a curable disease. It can only be managed with some major cancer treatments, which can help to improve the life expectancy of a patient and alleviate symptoms.
  • Symptoms of the disease include dry cough, chest pain, shortness of breath, fatigue, and so on (we will look into that as we move on).
  • Studies have shown that the average life expectancy of patients living with Pleural mesothelioma is 4 – 18 months, and the five-year survival rate is 10%.

Roughly 3,000 new cases of the Pleural Mesothelioma are being diagnosed by doctors in the United States every year.

Causes and Symptoms of Pleural Mesothelioma

Exposure to Asbestos fibers, which an individual can easily inhale into the lungs, remains the major cause of Pleural mesothelioma. After the microscopic cancerous mineral fibers are inhaled, their sharp and pointed shape makes it easy for them to lodge in the lungs and gradually move into the pleural lining.

Over many years, these fibers cause chronic inflammation, irritation, and genetic DNA changes that turn healthy pleural cells to becoming cancerous. After the first exposure to Asbestos of an individual, it usually takes up to 20 – 50 years for the malignant Pleural Mesothelioma to develop. It is because of this latency period that the disease is more predominant in older individual, usually 75 and above.

There are two layers to the pleural lining of the lungs. They are:

  1. The outer layer, which lines the entire Chest cavity under the ribs.
  2. The inner layer, which covers and protects the surface of the lungs.

A malignant tumor may develop on either of the two layers and can spread across to the other layer. They grow to form tumor masses as the nodules develop on the pleural surface. Fluid can also accumulate in the chest cavity as a result on these tumors.

It is the combination of a collection of pleural fluid and tumor masses increases pressure in the chest and prevents the lungs from its normal expanding, which causes difficulty in breathing.

When left untreated, these malignant cells can multiply themselves and cause damage to nearby healthy tissues, or even spread through the bloodstream and lymph system, forming new tumors on distant organs.

Symptoms

Patients living with Pleural mesothelioma have symptoms that make it difficult for them to breath, such as chest pain and shortness of breath, but they also experience a dry, raspy cough and difficulty in swallowing. For the majority, Mesothelioma symptoms are not noticeable until a later stage.

The symptoms of the Pleural Mesothelioma can include:

  • Difficulty in Swallowing
  • Coughing up blood
  • Persistent dry or raspy cough
  • Chest pain or painful breathing
  • Shortness of breath
  • Pain in the lower back or rib area
  • Swelling in the face or arms
  • Lumps under the skin on the chest
  • Fluid in the lungs
  • Unexplained weight loss and fatigue
  • Night sweats or fever

It is very rare for patients to mention weight loss and fatigue during their initial visit to a doctor. These symptoms only Manifests early if the cancer advances sooner than supposed to. Some patients also develop back pain, nerve pain, and swelling of the face or arms.

Several of the pleural cancer symptoms and conditions may also indicate the history of asbestos exposure of the individual, and the potential of a mesothelioma diagnosis. These symptoms and conditions include Pleural plaques, pleural effusions and pleural thickening.

In a 2020 study published in Case Reports, researchers discovered a rare case of mesothelioma through testing done on metastatic gastric and colonic polyps that were identified in image scans. These polyps were the only sign that the patient was living with the pleural mesothelioma.

  • Pleural Plaques: The most common sign that someone has a history of asbestos exposure is the presence of small areas of thickening on the pleura. Research has shown that pleural plaques are not cancerous and usually do not cause symptoms, but they may indicate an elevated risk of cancer.
  • Pleural Effusion: Excess fluid can build up between the two layers of the pleura due to irritation from the asbestos fibers. This condition is present in many pleural mesothelioma cases. Although a little fluid between the pleural layers is healthy, but too much of it puts pressure on the lungs. This pressure causes chest pain that worsens when the patient coughs or takes up a deep breath.
  • Pleural Thickening: It may become difficult and painful to breathe when large areas of pleura become stiffened because of scarring. The pleural thickening around both lungs is often a sign of significant continuous exposure to asbestos. This pleural thickening can get worse due to repeated episodes of pleural effusion, as the scar tissue collects.

Asbestosis

A pulmonary disease that is marked by progressive scarring of lung tissue, caused by asbestos exposure is what we refer to as Asbestosis. Though studies have shown that this condition does not affect the pleural lining, there is a greater risk of someone diagnosed with Asbestosis to develop an asbestos-related lung cancer rather than pleural mesothelioma. But the later has been documented in medical literature.

How the Diagnosis of Pleural Mesothelioma is done

The process of diagnosis begins when the doctor evaluates the initial symptoms of the disease. Breathing difficulty and chest pain warrants that a chest X-ray revealing the fluid buildup or tumors around the lung should be carried out. When further testing is required, a primary care physician refers the patient to a specialist.

In order to confirm diagnosis of a pleural mesothelioma, the specialist must use advanced imaging scans and tissue biopsies. In addition to identifying the cancer, determining the cell type and stage of the cancer is vital for creating an effective treatment plan.

Cell Types

Tissue biopsies help to identify the three different types of cells that make up pleural mesothelioma tumors. This information is very vital in determining the treatment plans. Most cases of the malignant mesothelioma are often diagnosed with a high number of epithelial cells (epithelioid cells). This cell type usually responds best to treatment of the cancer.

Sarcomatoid cells of the mesothelioma are the least common cell type. It is usually very aggressive and challenging to treat, and it mostly occurs in patients with the pleural mesothelioma.

The Biphasic cells type is a combination of the initial two cell types above. How it responds to treatment depends on the ratio of occurrence of the two cell types. If there is a presence of more epithelioid cells, it will respond better than tumors composed of more sarcomatoid cells type.

Stages of the Cancer

The Pleural Mesothelioma staging is how a doctor gets to determine the level of progression in the cancer in the body of a patient. The treatment options that the doctor may prescribe for the patient is being influenced by the stage.

The TNM staging system was created by the International Mesothelioma Interest Group, and it is the most widely used staging system for pleural mesothelioma.

The early stages 1 and 2 indicate localized tumors, while the later stages 3 and 4 indicate spreading tumors.

When a doctor diagnoses a patient in stage 1 or 2, they tend to have more options for treatment of the pleural mesothelioma, including surgery, which offers the best increased survival chances. In the later stages 3 and 4, treatment options become limited, since the cancer has started spreading across various other vital organs in the body system.

Below is a view of the life expectancy for patients eligible for surgery by stages.

  • Stage 1: Life expectancy is around 22 months. The tumors remain localized in and around the lining of one lung tissue.
  • Stage 2: Life expectancy is around 20 months, and the cancer cells are beginning to enter nearby lymph nodes.
  • Stage 3: The life expectancy here is around 17 months. At this stage the cancer has spread out to nearby tissues and distant lymph nodes.
  • Stage 4: Life expectancy is about 14 months. At this stage 4, the cancer has spread across distant organs all over the body.

Treatment Options for the Pleural Mesothelioma

Standard treatment options for the pleural mesothelioma can include surgery, chemotherapy, and radiation therapy.

Chemotherapy is the most common type of treatment for the Pleural Mesothelioma. Doctors often prescribe a combination of medicines (multimodal therapy) if they diagnose a patient early enough in the disease process. These treatments can help improve symptoms, such as difficulty in breathing, chest pain, and general improved survival.

Patients can have access to these therapies at top cancer centers that specialize in pleural mesothelioma treatment across the nation.

Chemotherapy

Chemotherapy is known to be the most common pleural mesothelioma treatment. The therapy makes use of one or more drugs, usually a combination of cisplatin or carboplatin and pemetrexed (Alimta) to kill cancer cell or prevent them from being able to reproduce. The level at which patients respond to chemotherapy has improved due to recent advances, but the success rate remains generally low.

A new method of delivery for chemotherapy known as Heated Intrathoracic Chemotherapy (HITHOC) is applied directly to the pleural cavity, following surgery. The chemotherapy drugs are heated before they are being circulated all over the pleural cavity.

Surgery

Surgery is used to diagnose the cancer, remove tumor and relieve symptoms. A common diagnostic surgery includes thoracoscopy, which is a minimally invasive procedure to collect samples of the tumor tissue for biopsy testing.

To control symptoms, patients diagnosed with later stages of the disease may benefit from therapeutic surgeries.  A thoracenthesis is a minimally invasive surgery that is done to remove fluid from the pleural cavity with the use of a tube that is inserted through a small incision in the chest region. A pleurodesis also removes fluid, but it takes the whole procedure a step further by eliminating the pleural space. This pleurodesis is achieved by fusing two pleura layers together. The pleurodesis prevents any future occurrence of pleural effusion.

Patients with the pleural mesothelioma that were diagnosed at early stage benefit the most from tumor-removing surgeries. The goal of the surgery is to remove cancer and prevent it from recurring as long as possible.

The two most common surgery processes for removal of tumor of pleural mesothelioma are Extrapleural Pneumonectomy and Pleurectomy & Decortication. A pleural mesothelioma cancer specialist can always determine your eligibility for surgery and advice you on which procedure is more suitable for you diagnosis.

  • Extrapleural Pneumonectomy: is a more aggressive surgical option where the Extrapleural Pneumonectomy removes the pleura, the diaphragm the heart sac (pericardium), and the entire cancerous lung.
  • Pleurectomy & Decortication: is also known as P/D or radical pleurectomy. It involves the removal of the tumors and affected pleura (lining of the lung).

Radiation Therapy

Tumor size can be decreased, and cancer cell destroyed by implementation of Targeted Radiation. Radiation therapy cannot cure pleural mesothelioma, but it can effectively manage chest pain. Cancer recurrence after surgery can also be prevented with the help of this radiation therapy.

External beam radiation therapy is the most common form of the pleural mesothelioma radiation therapy. Sessions only take a few minutes, and are fast and painless.

Other Emerging Treatment options

Emerging treatment options to take care of pleural mesothelioma in patients include novel therapies such as Immunotherapy, Gene therapy and Photodynamic therapy. Researchers are refining these treatment options to fight cancer more effectively, while still causing fewer side effects on patients.

Through a pleural mesothelioma clinical trial, a patient may be able to receive experimental therapy. And through compassionate use of programs, some patients may be eligible for immunotherapy drugs and other emerging treatment options.

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