Mesothelioma is a rare, highly aggressive type of cancer that can be caused by exposure to asbestos. This cancer can affect the lining of the lungs or the abdominal lining and is the most lethal of all asbestos related diseases. Unfortunately it is also one of the most prevalent.
The time between first exposure to asbestos and the onset of the symptoms could be anywhere from 20 years to 50 years. The latency period for mesothelioma is rarely less than 20 years.
There are three types of Mesothelioma. Each type has its own distinct set of symptoms.
Pleural Mesothelioma – This is a cancer of the mesothelium or lining of the lungs. It is the most common type of mesothelioma, accounting for 75% of all diagnoses. When the fibres are inhaled, they get lodged in the mesothelium that lines the chest and lungs, causing the lining to get irritated and inflamed. As the disease progresses the pleura thickens and forms a hard tumour mass that compresses the lungs. Symptoms of pleural mesothelioma range from shortness of breath and chest pain to persistent coughing and sometimes fluid build up in the chest.
Peritoneal Mesothelioma – Cancer of the mesothelium surrounding the abdomen is known as peritoneal mesothelioma. It is caused by ingesting asbestos fibres and accounts for about 20 % of all diagnoses. Symptoms of peritoneal mesothelioma include stomach pain, weight loss and build up of fluid.
Pericardial Mesothelioma – Pericardial cancer affects the mesothelium or lining surrounding the heart. This is the rarest form of mesothelioma and is rarely diagnosed while the patient is still alive. Symptoms of pericardial mesothelioma are similar to those of other heart ailments and include heart murmurs and chest pain.
Mesothelioma has 4 stages, each marking an increase in severity. Stages are determined according the location of the cancer and by how much it has spread to the rest of the body. The farther the cancer spreads, the more advanced the staging. Stage 4 is the most advanced and dangerous diagnosis.
Mesothelioma is almost exclusively caused by exposure to asbestos. This exposure can occur either occupationally (working in an industry where asbestos is used), environmentally (living in the vicinity of any workplace that uses asbestos) or as a result of secondary exposure (inhaling the fibres or dust that may be present on another person’s clothes, skin or hair).
When asbestos fibres are inhaled, they lodge in the mesothelial tissue of the lungs, abdomen or heart. Over a period of time, these fibres trigger a series of physical and metabolic changes leading to inflammation, scarring and genetic damage that sometimes leads to cancer. These asbestos fibres can become trapped in the lining of the lungs or in the lining of the abdominal cavity or the heart. Once the biological damage starts, the stage is set for the development of malignant mesothelioma.
The fibres that penetrate the lung cause cancer in the pleura or the lining of the lung. Those that penetrate the bowel or stomach cause cancer in the peritoneum or the lining of the abdomen and the fibres that penetrate the heart cause cancer in the pericardium or lining of the heart.
Mesothelioma: Risk Factors
Construction workers and workers employed in the shipbuilding industry, asbestos mines and asbestos processing plants are at highest risk for mesothelioma. Although asbestos is no longer used in any of these industries today, the fibres and dust can still become airborne during maintenance and repair work, putting workers at risk for all types of asbestos related diseases.
Other occupations at a high risk for mesothelioma include roofing contractors, HVAC engineers, maintenance workers, painters, pipe fitters, plasterers and demolition crews. Higher-exposure occupations include plumbers, electricians, carpenters, boilermakers and joiners.
People living in residential areas in the vicinity of an asbestos mine or asbestos related industry are also at high risk.
Mesothelioma: The Diagnosis
Imaging technology, such as X-Rays, PETs, CATs and MRI are the primary tools that are used to determine the presence of any cell growth. A doctor may start with a biomarker test to check a patient’s blood for certain common signs that the cancer is present. A needle or surgical biopsy may also be done to remove cells and tissue for review in order to obtain a more conclusive diagnosis of mesothelioma.
Mesothelioma: Treatment & Prognosis
Mesothelioma is an extremely aggressive cancer that is very difficult to treat as it is often discovered only when it is in an advanced stage. While there are a few treatment options available, most of these treatments aim at managing the symptoms and slowing down the progression of the disease. There is no known cure.
The most effective treatment for is multimodal or a combined use of different therapies. The use of radiation therapy or chemotherapy after surgery has produced the most promising results so far. The exact treatment used depends on the type and location of the cancer as well as the stage it is at.
There are several factors that impact the prognosis in someone who has mesothelioma.
Type of cancer – Pleural mesothelioma, which is the most common, also has the best rate of survival. Peritoneal mesothelioma, which is the second most common type of cancer has the second best rate of survival. Less common types of cancer such as pericardial cancer are the most difficult to treat and have the lowest survival rate.
Stage of the disease – How early the disease is diagnosed and how soon treatment can begin play key roles in the prognosis for the cancer. Because of the long latency period, the cancer is often not diagnosed until it has reached Stage 3 or 4, when the symptoms finally appear. Unfortunately, many of these symptoms are common to a wide range of respiratory diseases including the flu or pneumonia. This often results in misdiagnosis.
Metastasis – By the time the diagnosis is finally confirmed, oncologists will often find that the cancer has metastasized or spread from the primary location to other parts of the body, often to the nearby organs and lymph nodes. The extent of the metastases will determine what type of treatment is recommended as well as the prognosis.
General health of the patient – Patients who are younger and stronger live longer than those of advanced age who have other health problems. Older people can often be already dealing with issues such as high blood pressure, diabetes and heart disease, which severely limit treatment options that are available to them.
Today there are several clinical trials being carried out that offer patients access to emerging treatments such as photodynamic therapy, gene therapy and immunotherapy treatments. These are still at the trial stage however and their long-term effectiveness has not yet been proven.