Mesothelioma is a type of cancer that affects the lungs, abdomen, or heart. It is an aggressive form of cancer associated with exposure to asbestos. The name “mesothelioma” comes from the part of the body where the disease originates: the mesothelium or the layer of cells that act as protection for internal organs.
The definitive cause of mesothelioma is difficult to discern because the cancer develops during the course of at least a decade, sometimes over 50 years. To date, exposure to asbestos is the only settled caused of malignant mesothelioma, accounting for about 90 percent of known cases.
Asbestos is a fibrous material that was previously used for items like fabrics and building insulation. Because it is heat-resistant, asbestos was widely used for many purposes. Exposure occurs when someone swallows or inhales asbestos fibers. The fibers can lodge in soft tissue, causing irritation, inflammation, and scarring. Asbestos reactions in the body can impede a person’s natural defenses against cancer, allowing the scar tissue to develop into cancerous tumors.
Symptoms will generally depend on the location of the cancer. Symptoms can include:
- Chest pain or back pain
- Difficulty swallowing
- A chronic cough, sometimes producing blood
- Hoarseness of the voice
- Shortness of breath
- Fluid on the lungs
- Abdominal pain or swelling
- Nausea and vomiting
- Bowel obstruction
- Abnormal heart rhythm
- Fluid on the heart
- Nerve damage in the limbs or face
The above symptoms are somewhat nonspecific and can be indicative of several conditions. These vague symptoms, combined with the delay in cancer development after asbestos exposure, make it difficult for doctors and patients to arrive at mesothelioma diagnoses.
The mesothelioma diagnostic process will vary from patient to patient. Often patients will need to make several trips to primary care doctors and specialists before they receive solid diagnoses. Usually, diagnoses will involve the following steps:
- Thorough information gathering by a doctor about a patient’s medical history
- Medical examinations and evaluations
- X-rays, MRIs, or other imaging
- Biopsies or tissue sampling
Physicians will ordinarily begin with conservative testing and move to more invasive testing as necessary. Many patients can be diagnosed with imaging and bloodwork, as physicians will often be able to see tumors and observe abnormal substances in the bloodstream that are indicative of cancer. However, doctors frequently require surgery and biopsy to be completely sure a patient has mesothelioma. Absent a biopsy, the disease can be confused with many other conditions.
There are four known types of mesothelioma, which are based on the area of the body affected. The four main types of mesothelioma are:
- Pleural Mesothelioma – Mesothelioma cancer affecting the lungs. This is the most common type of mesothelioma by far, accounting for about 75 percent of all cases. Pleural mesothelioma develops in the pleura or lining of the lungs. Typical symptoms will include chronic chest pain, cough, fever, and unexplained weight loss.
- Peritoneal Mesothelioma – Mesothelioma cancer affecting the organs in the abdominal cavity. This is the second-most common type of mesothelioma, accounting for approximately 10 percent of all cases. Typical symptoms will include abdominal pain, nausea or vomiting, and fever.
- Pericardial Mesothelioma – Mesothelioma cancer affecting the heart. This is a rare type of mesothelioma, accounting for only about 1 percent of all cases. Typical symptoms will somewhat mimic a heart attack and include nausea, shortness of breath, and chest pain.
- Testicular Mesothelioma – Mesothelioma cancer affecting the testes. This is an extremely rare type of mesothelioma, with only about 100 total cases reported. Because of its rarity, a specific set of symptoms has not been identified. Some patients will experience swelling or fluid buildup in the scrotal area.
In addition to understanding the location of the cancer, doctors will examine the cell type of the patient’s tumors. Cells can be epithelioid, sarcomatoid, or biphasic. Identification of the cell type will help a doctor understand how quickly the tumors will grow, how likely the cancer is to metastasize/spread, and how effective available treatments might be for a patient. All of this information helps doctors discuss expectations and prognoses with patients.
Patients with epithelioid cell tumors usually have the best prognoses. These cells are typically found in pleural mesothelioma. Patients with sarcomatoid cell tumors typically have poor prognoses, as these tumors are the most aggressive. Sarcomatoid cells are usually associated with pleural mesothelioma or peritoneal mesothelioma. Patients with biphasic cell tumors have both epithelioid and sarcomatoid cells in their tumors. Their prognoses will depend on the amount of each cell type.
Upon arriving at an appropriate diagnosis and identifying the cell type, a physician will develop a treatment plan individualized to the type of mesothelioma a patient has, including the tumor cell type, and the advancement of the cancer.
Though their occurrence is rare — identified in only about 200 cases total — some mesothelioma tumors are benign, meaning they are noncancerous. These tumors are not well understood but generally will not spread or grow in the manner usually found in cancerous tumors. Benign mesothelioma will typically manifest as a single mass.
Even benign tumors have the potential to turn malignant so that many physicians will recommend surgery to patients with noncancerous mesothelioma. Removal of the mass seems to produce the best chance of cancer prevention and the lowest rate of recurrence.
To date, there is no cure for malignant mesothelioma. However, several treatment options exist to address the size of the tumors, their potential to spread, and the symptoms they produce. The most common forms of treatment include:
Surgery is usually considered “primary” therapy, designed to remove as much of the cancer as possible and halt progression or alleviate discomfort. The effectiveness of surgery will depend on location and metastasis.
Chemotherapy will often be used before surgery (referred to as “neoadjuvant” therapy) in an attempt to shrink tumors and provide patients with more surgical options. Chemotherapy is also a treatment option post-surgery (referred to as “adjuvant” therapy) to prevent cancer progression. Doctors will also often use radiation therapy, sometimes in combination with chemotherapy, to fight cancer cells molecularly.
In addition to mesothelioma, asbestos has been linked to the following severe medical conditions:
- Lung cancer
- Ovarian cancer
- Laryngeal cancer
- Testicular cancer
- Pleural plaque, thickening, and effusion
Asbestos’s varied public dangers have resulted in the material’s near-elimination from commercial use. However, because of the widespread nature of its use historically, the battle against asbestos is far from over.