Asbestos Exposure and Mesothelioma
Mesothelioma is a rare and aggressive form of cancer whose only known cause is asbestos exposure. While in most cases mesothelioma develops on the outer lining of the lungs, it can also affect the lining of the abdomen, heart, and testicles. Every year, between 2,400 and 2,800 people are diagnosed with this malignant disease in the U.S. only, 80% of whom were exposed to asbestos in the workplace. The term mesothelioma pertains to the membrane on which this form of cancer occurs – the mesothelium. It covers the majority of internal organs in the body and has multiple functions, such as serving as a protective layer of cells.
Since it has a long latency period, mesothelioma develops within 20 to 50 years of first contact with airborne asbestos. The human body cannot naturally eliminate asbestos fibers due to their rough texture and a needle-like shape. Consequently, the majority of inhaled or ingested fibers will lodge in the lining of the organs, which might produce severe inflammation and tissue scarring over the years. In turn, these symptoms will gradually give way to the development of cancer. Although mesothelioma is typically associated with a history of heavy and prolonged asbestos exposure, anyone who came in contact with airborne fibers is at risk.
Mesothelioma Types and Symptoms
Depending on the location of the malignant tumor in the body, mesothelioma is of four types: pleural, peritoneal, pericardial, and testicular. Each type of mesothelioma has a set of specific symptoms and requires a different treatment approach.
Accounting for over 75% of cases, pleural mesothelioma is the most common type. It affects the outer lining of the lungs (pleura). Since the early symptoms of pleural mesothelioma are very similar to those of less severe conditions, such as pneumonia or asthma, it is often diagnosed when cancer has produced extensive damage to the lungs. For this reason, pleural mesothelioma has a poor prognosis, with a life expectancy ranging between 6 and 12 months. However, when the disease is detected in its early stages, it tends to respond better to treatment, which improves prognosis considerably.
The symptoms of pleural mesothelioma include:
- a persistent dry cough
- chest pain
- shortness of breath
- difficulty swallowing
- lumps under the skin in the chest area
- unintentional weight loss
- coughing up blood
- loss of appetite
- night sweats
In 90% of cases, people suffering from this type of mesothelioma experience pleural effusion, which occurs when excess fluid accumulates between the two layers of the pleura. This condition may hinder lung capacity to a great extent, also making deep breathing and coughing painful.
Significantly less common than the former, this disease represents between 15 and 20 percent of all diagnosed mesothelioma cases. As the name suggests, peritoneal mesothelioma develops on the lining of the abdominal cavity – the peritoneum. It generally has a better prognosis than pleural mesothelioma, entailing a median life expectancy of one year. Similarly, early diagnosis can prolong survival to a great extent: most peritoneal mesothelioma patients whose disease is discovered at stage 1 or 2 will live for 5 years or more, as they are usually eligible for aggressive surgery.
The most common symptoms of peritoneal mesothelioma are:
- changes in bowel habits
- abdominal pain
- night sweats
- abdominal swelling
- loss of appetite
- nausea and vomiting
- diarrhea or constipation
- unexplained weight loss
- excess fluid in the abdomen
- feeling full after eating small amounts of food
Additionally, peritoneal mesothelioma can cause a series of other symptoms, such as hypoglycemia (low blood sugar), venous thrombosis (blood clots which form in a vein) or thrombocytosis (high platelet count). Both inhaled and ingested asbestos fibers can lead to this disease. While fibers in the lungs can reach the peritoneum via the lymphatic system, asbestos fibers which were swallowed can travel to it through the digestive system.
This type of mesothelioma is very rare, occurring in less 2% of all people suffering from this disease. Since pericardial mesothelioma has such a low prevalence, approximately 200 cases are documented by medical literature at the moment, makes diagnosing it quite challenging even for specialists. Occurring on the lining of the heart (pericardium), this malignant disease has a very poor prognosis. The average life expectancy for pericardial mesothelioma patients is 6 months.
Some of the symptoms frequently associated with pericardial mesothelioma are:
- heart palpitations
- chest pain
- shortness of breath
- heart murmurs
- irregular heartbeat
- a chronic cough
- night sweats
- difficulty breathing
- pericardial effusion (excess fluid in the chest cavity)
As the rarest type of mesothelioma, testicular mesothelioma represents less than 1% of all diagnosed cases. It develops on the tunica vaginalis testis, which the inhaled or ingested asbestos fibers also reach by travelling through the lymphatic system. Although the disease is extremely uncommon, it has a substantially better prognosis than the other three mesothelioma types, with a median life expectancy ranging between 20 and 23 months.
The most common symptoms of testicular mesothelioma include:
- testicular swelling
- excess fluid in the scrotum
- a lump in the testicles
Another criterion for classifying mesothelioma is cell type. There are three types of cells which can be involved in a mesothelioma tumor, as follows:
- Epithelioid. Between 50 and 70 percent of mesothelioma tumors display this type of cells, which is also the most responsive to treatment. Epithelioid cells have a uniform appearance and occur in complex patterns.
- Sarcomatoid. Mesothelioma tumors containing sarcomatoid cells are the rarest, accounting for less than 20% of all diagnosed cases. These spindle-shaped malignant cells are also the most aggressive, spreading more rapidly than the previous type and thus implying a shorter life expectancy. Sarcomatoid cells are highly resistant to treatment as well.
- Biphasic. When both epithelioid and sarcomatoid cells occur, a biphasic mesothelioma tumor is diagnosed. Prognosis depends primarily on which type of cancerous cells is present in a larger amount. A tumor which contains more epithelioid cells entails a better prognosis than one with a majority of sarcomatoid cells. Biphasic cells are found in up to 35% of mesothelioma patients.
Since mesothelioma is a very complex form of cancer which can easily be mistaken for a common respiratory infection or even entirely overlooked by medical professionals due to its rarity, a combination of diagnostic tools is required for a reliable evaluation. The usual tests and examination procedures specialists employ complementarily when diagnosing pleural mesothelioma are:
A chest X-ray can detect a wide range of lung abnormalities, including tumors, as well as reveal their exact location on the organ. However, since it can only provide information regarding the appearance of the lungs, this diagnostic method is limited. By simply examining a patient’s radiographs, a specialist is unable to determine whether a tumor is malignant.
CT, MRI or PET scans
Typically recommended after a tumor is detected on radiographs, these imaging techniques allow a complex, in-depth examination of internal organs and tissues. Unlike X-rays, which provide a 2D perspective, CT, MRI, and PET offer 3D images of the tumor, which will help your doctor assess the stage of cancer, as well as determine whether you are eligible for surgery.
The most common blood tests utilized in the diagnosis of mesothelioma are the MESOMARK assay, Fibulin-3, the SOMAmer panel, and the Human MPF Elisa Kit. Nevertheless, a high concentration of a biomarker in the blood does not necessarily indicate the presence of mesothelioma, as there might be another factor at play.
A tissue biopsy is the most reliable diagnostic method when it comes to mesothelioma. During this procedure, a surgeon will collect one or multiple samples of tissue from the tumor and a pathologist will subsequently analyze them. Following a tissue biopsy, your doctor will be able to confirm the diagnosis of mesothelioma, as well as identify the occurring type of cancer cells.
Mesothelioma vs. Lung Cancer
Because both pleural mesothelioma and lung cancer affect the lungs, these two forms of cancer are often mistaken for each other. However, mesothelioma is a completely distinct disease from lung cancer from numerous points of view. Differentiating between mesothelioma and lung cancer might be challenging even for experts, hence the importance of visiting a specialist if you experience worrisome symptoms. Moreover, each disease requires a specific treatment approach which, in the case of misdiagnosis, you will not benefit from. The main differences between these two malignant diseases refer to:
- the location of tumors on the lungs – while lung cancer develops inside the organs, mesothelioma occurs on the outer lining of the lungs
- latency period – the onset of lung cancer tends to be more rapid than that of mesothelioma: it usually takes between 20 to 50 years for mesothelioma to develop, whereas lung cancer ensues within 10 to 20 years after first exposure to asbestos
- cause – unlike mesothelioma, which is exclusively the result of asbestos exposure, lung cancer can appear as a consequence of multiple factors, including tobacco smoking and exposure to other toxic agents such as radon gas
- tumor appearance – while lung cancer occurs in individual, well-defined tumors, mesothelioma is diffuse in nature, developing as multiple smaller masses spread across the surface of the pleura
How Is Mesothelioma Treated?
The standard treatment for mesothelioma consists in a multimodal approach combining surgery, chemotherapy, and radiation therapy. This treatment approach is currently the most effective, being able to prolong life expectancy considerably if cancer has not metastasized. It is worthy of note that not everyone diagnosed with mesothelioma will qualify for surgery, as this procedure is quite aggressive and thereby not suitable to patients whose disease is very severe. Depending on the extent to which cancer has spread, the surgeon might also remove lymph nodes, the diaphragm, and/or a portion of the affected lung in addition to the pleura.
Besides the standard approach, a series of experimental treatments are available to mesothelioma patients in clinical trial. Oftentimes, mesothelioma sufferers experience significant health benefits following this type of treatments, including partial tumor remission and extended survival. Some of the cancer therapies suitable for mesothelioma which are still undergoing research and improvement are:
- gene therapy – since gene mutations are present in plenty of cancer patients, researchers are trying to develop effective ways of attending to problematic genes
- immunotherapy – this treatment approach focuses on boosting the immune system, which is severely damaged in most cancer patients
- photodynamic therapy – a combination of photosensitizing drugs and light has proved to be quite efficient in eliminating malignant cells with minimal side effects
Mesothelioma is a very complex form of cancer and will occur differently in each patient. Therefore, it always requires an individualized treatment approach, which only a specialist with vast experience in diagnosing and treating asbestos-related diseases will be able to provide. If you have a history of asbestos exposure and notice one or more symptoms associated with mesothelioma, we strongly advise you to seek medical assistance immediately. Early detection is vital for a good prognosis and since mesothelioma progresses very rapidly, it is crucial to visit a specialist as soon as possible.
Finally, because the rate of misdiagnosis is alarmingly high, we also suggest you seek a second opinion from another mesothelioma expert. Please feel free to contact us at 760-208-4196 or by filing out the form on our Contact page and we will gladly help you find a specialist in your area.