Mesothelioma is a rare type of cancer that occurs in the thin protective layer of tissue lining important internal organs such as the heart and lungs. It is caused by exposure to asbestos, usually at the workplace, and can take as long as 10 to 50 years to develop after the first exposure to asbestos. When individuals are exposed to asbestos, the fibers work their way through the lungs and into the lining surrounding internal organs eventually causing cancer. This membrane surrounding these vital organs is called the mesothelium, thus the name mesothelioma.
High rates of mesothelioma occur in people who mine asbestos, manufacture asbestos products, work with asbestos products, live with asbestos workers, or work in buildings or homes containing asbestos.
The diagnosis of mesothelioma is usually made by a chest X-ray or High Resolution Computerized Tomography (HRCT), and is usually confirmed by a pathologist either examining fluid or by a tissue biopsy. Diagnosis usually occurs after the age of 65 and most deaths occur around age 70. The disease was rare before the commercial use of asbestos and is still an extremely rare form of cancer.
Mesothelioma accounts for less than 1% of all cancers in the United States. Mesothelioma typically occurs in men more than women. The majority being men over the age 60 who served in the military or worked in construction. However, anyone exposed to asbestos could be at risk for developing the disease.
The time of an individual’s initial exposure to asbestos until the development of mesothelioma, lung cancer, or asbestosis is typically around 10 to 50 years later. This concept is known as latency. The significance of latency is that individuals who were frequently exposed to asbestos don't develop mesothelioma until decades later in their life.
There are four types of mesothelioma: pleural (lungs), peritoneal (abdomen), pericardial (heart), and testicular. In addition, mesothelioma can be categorized based on cell type – epithelioid, sarcomatoid, or biphasic – and according to which cells are affected.
Pleural Mesothelioma is the most common type of mesothelioma, accounting for roughly 75 percent of mesothelioma diagnoses. This most common form of mesothelioma accounts for approximately 2,500 – 3,000 cases a year in the United States. It affects the tissue that surrounds the lungs known as the pleura. It is caused by inhaling asbestos fibers into the lungs.
Peritoneal mesothelioma is the second most common type of mesothelioma. It accounts for less than 20 percent of mesothelioma diagnoses. This form of mesothelioma is discovered in approximately 250 cases a year. It occurs in the lining of the abdomen (the peritoneum). It is caused by the ingestion of asbestos fibers.
Pericardial mesothelioma is a rare form of mesothelioma that develops in the lining surrounding the heart (the pericardium). This type of mesothelioma accounts for approximately 5 percent of the newly diagnosed cases per year.
Testicular mesothelioma is an extremely rare, and accounts for less than 1 percent of mesothelioma diagnoses. This asbestos cancer occurs around the lining of the testicles.
Epithelial cells are one of the four basic types of cells in the human body and line the cavities, blood vessels, and organs throughout the body. Once exposed to asbestos these normally healthy cells mutate into cancer cells or epithelioid mesothelioma. The prognosis for epithelioid mesothelioma is more favorable, with more treatment options available, than those with sarcomatoid or biphasic mesothelioma.
Sarcomatoid cells are located in connective tissue such as bone, cartilage, muscle, blood vessels, or lymphoid tissue throughout the body. Sarcomatoid mesothelioma is the least common of the mesothelioma cell types and is unfortunately the most resilient to cancer treatment. Diagnosis is difficult because these cells can appear healthy even though they may have become malignant after being damaged from exposure to asbestos. The treatment options available for sarcomatoid mesothelioma are limited and the most common approach is palliative care. This extremely aggressive form of cancer is also known as spindle-shaped/spindle-cell mesothelioma, based on their appearance, or sarcomatous mesothelioma.
Biphasic mesothelioma is a combination of epithelioid and sarcomatoid cells. Understanding the different types of mesothelioma and which cells have been affected can assist in making important treatment decisions.
Mesothelioma is commonly diagnosed after a person goes to a physician for symptoms they are experiencing. If you have symptoms of mesothelioma, which can vary depending on which type of mesothelioma you have, and a history of asbestos exposure contact your physician immediately, it is important to obtain a mesothelioma diagnosis early on in order to get the best possible prognosis for the disease. Unfortunately, most patients with mesothelioma will not develop symptoms until the mesothelioma cancer is in the later stages. Your physician will obtain your work and medical history and most likely perform a physical exam. It is essential during this visit to inform your physician if you have ever been exposed to asbestos, because mesothelioma is extremely rare, difficult to diagnose, and the symptoms are common in other illnesses, most physicians will not likely suspect mesothelioma as a possibility unless they are aware of a history of asbestos exposure.
If mesothelioma is a possibility, you will then be referred to another physician such as a pulmonologist or oncologist, who will perform a variety of tests based on your current health, these tests may include imaging tests and/or blood tests, if either of these preliminary tests indicate mesothelioma as a possibility, a biopsy will be ordered.
Imaging tests such as x-rays, CT scans, PET scans and MRIs, are used to take pictures of the inside of your body. These tests can be used to look for cancer, find out how far the cancer has spread, and determine whether cancer treatment is working. If an abnormal mass that resembles mesothelioma is detected, your doctor will order a biopsy.
Blood tests for mesothelioma include the MESOMARK test, SOMAmer test and Human MPF test. These blood tests cannot confirm a diagnosis of mesothelioma, however, there are 3 substances in the blood which may be elevated (fibulib-3, osteopontin, and soluble mesothelin-related peptides (SMRPs)) in individuals who have mesothelioma, therefore, high levels of these substances can make a mesothelioma diagnosis more likely.
Only a biopsy can determine a mesothelioma diagnosis. It is the last stage of the diagnostic process. It involves removing cells from an abnormal area in the body and examining the cells under a microscope. There are three types of biopsies that are used for mesothelioma: fine-needle biopsies, endoscopic biopsies, and open surgical biopsy.
A long, thin, hollow needle is inserted directly into the mass to obtain tissue samples. This is a quick procedure and there is little downtime, however, in some cases, the tissue sample may be too small to make a diagnosis and a more invasive procedure may be needed, such as a surgical biopsy.
A narrow, flexible tube called an endoscope, which has a tiny camera and a light at the end is inserted through a very small incision in the body to obtain tissue samples. It is performed in an operating room while you are under general anesthesia.
Small incisions are made on the abdomen to examine the abdominal organs and obtain tissue samples from any suspected peritoneal mesothelioma tumors.
A very small incision in made in the chest wall to look at the pleura and obtain tissue samples from any suspected pleural mesothelioma tumors.
A small incision is made in the neck to examine the area between the breastbone and lungs and obtain tissue samples from any suspected pericardial mesothelioma tumors.
Open surgical biopsy
Sometimes, when a needle or endoscopy biopsy is not able to confirm a diagnosis or the location of the tumor is too hard to reach using a needle or endoscope, a more invasive open surgical biopsy may be needed to obtain a tissue sample. In this case, an open surgical biopsy will take a larger sample of the tumor or, in some cases, remove the entire tumor entirely.
There are two types of open surgical biopsies:
A thoracotomy is performed on patients who may have either pleural mesothelioma or pericardial mesothelioma. It is an open-chest surgical procedure.
A laparotomy is performed on patients who may have peritoneal mesothelioma. It is an open abdominal procedure.
Please note, it is always important to get a second opinion if you have been diagnosed with mesothelioma.
If you have been diagnosed with malignant mesothelioma it is important to know at what stage or progression your cancer was discovered in order to determine the best course of treatment. There are four stages of cancer.
The earliest stage of mesothelioma and, if discovered during this stage, the patient has the best prognosis and more treatment options available.
During this stage the mesothelioma has not spread to other parts of the body. The cancer is localized and, therefore, patients have more options for treatment. Patients may elect to have surgery, chemotherapy, and/or radiation.
In stage 3, Mesothelioma has already metastasized to other parts of the body making it more difficult to treat. Surgery is generally not an option at this stage since the cancer has already spread.
In the last stage, the mesothelioma has spread throughout the body and affected multiple organs and parts of the body. Patient’s treatment options are extremely limited and typically palliative care is the only course to ease suffering