Mesothelioma is an extremely rare form of cancer which affects the mesothelium, a thin tissue that lines the inside of the body cavities and surrounds the organs. This tissue both protects the organs and produces a lubricating fluid that prevents friction during their movement.
The mesothelium can be found in several different locations in the body; when it encases the lungs, it is called the pleural mesothelium. The pericardial mesothelium covers the heart, while the peritoneal mesothelium envelops the abdomen. There is also a testicular mesothelium.
The Link Between Asbestos Exposure and Mesothelioma
Mesothelioma is almost always associated with exposure to asbestos. Once a predominant material used in the construction and manufacturing sectors, asbestos was popular because of its non-conductive, non-flammable and heatproof qualities. It is also strong, pliable and inexpensive. When asbestos is damaged or cut, however, it can disintegrate into a fine dust composed of microscopic, sharp fibers. These fibers are too small to be caught by the lungs’ natural filtration system, and eventually make their way to the mesothelium, where they penetrate the cells. They cause irritation, as well as damage to the DNA, leading to mitosis – the random and uncontrollable cell division that characterizes tumor formation.
There is a long latency period between the contact with asbestos and the development of related diseases like mesothelioma; it can take 20 to 50 years before symptoms become evident. In the interim, a tumor may have spread across most of the mesothelium, and the cancer may have metastasized to other organs. Most patients are not diagnosed with mesothelioma until they are 55 or older, although there are some notable exceptions to this rule.
The most common form of mesothelioma, malignant pleural mesothelioma, has symptoms which can easily be mistaken for those of other respiratory conditions. A dry cough, chest pain, shortness of breath, and fatigue can lead the patient to believe that he or she has a chest cold or a mild bout of the flu. Often, patients don’t seek medical treatment until these symptoms have persisted for some time, further complicating the diagnosis and treatment of mesothelioma.
Similarly, physicians frequently misdiagnose this form of cancer, since it is so rare and since it can resemble emphysema, bronchitis or pneumonia. Knowledge of the patient’s asbestos exposure history can help the physician to screen for mesothelioma.
Pericardial mesothelioma symptoms are similar to those associated with the pleural variety, but may also include heart palpitations or murmurs. Peritoneal mesothelioma presents with stomach pain, bowel obstruction, rapid weight loss, and swelling or lumps in the abdominal area. Testicular mesothelioma is so rare – fewer than 100 cases have ever been diagnosed – that the symptoms are unknown, but any changes to, or pain in, the testes should be closely monitored.
The physician may order x-rays, a CT scan or an MRI, as well as a biopsy, if mesothelioma is suspected. A needle biopsy may be conducted, but it’s more likely that the patient will undergo excision biopsy using thoracoscopy, peritoneoscopy, bronchoscopy or mediastinoscopy – all procedures which allow the physician to visually inspect for the presence of tumors as well as to collect a small sample of tissue. This sample will be sent to a pathologist for review.
Treating mesothelioma can be tricky. If it is caught in the early stages, surgery may be an option. This also depends on the location and size of the tumor. Mesothelioma, however, is almost always diagnosed in Stage III or Stage IV, when it is inoperable. In some cases, radiation therapy can be administered, but the mesothelioma tumor’s diffuse nature – it spreads across the membrane like a rind, rather than forming a discrete lump, as in other cancers – as well as its proximity to the major organs makes radiation risky.
Another option for treating this disease is chemotherapy. Currently there is one drug approved by the FDA for the treatment of mesothelioma, Alimta. It is usually used in combination with cisplatin or carboplatin, and chemotherapy is often given either before or after surgery as an adjutant therapy. Since each case of mesothelioma is different, the treatment plan will be unique to the patient.
Some patients, based on their age, strength, and overall health, may choose not to undergo these aggressive treatments. Each has debilitating side effects, and some patients would rather pursue pain management methods in order to live out the remainder of their life as comfortably as possible.
Palliative treatments are not intended to cure the cancer, but instead provide relief from its painful symptoms. One of the most common of these symptoms is a condition called pleural effusion, or fluid build-up in the space between the pleural mesothelium lining the chest and that covering the lungs. Several minor surgical procedures can alleviate this; thoracentesis drains the fluid by means of a thin needle and catheter, and pleurodesis actually fuses the linings together with talc or other irritating agent.
Some patients have found relief using alternative therapies such as nutritional or herbal supplements, massage, acupuncture and hypnosis. There are also a number of experimental therapies on the horizon that are providing hope to mesothelioma patients. These include photodynamic therapy, immunotherapy, gene therapy, and the development of new chemotherapy drugs.
Since mesothelioma is almost exclusively linked to asbestos exposure, workers who used or worked around asbestos on the job have the most risk for diagnosis of this dreadful disease. It’s also possible to breathe asbestos fibers that are brought home on the workers’ clothing, so their family members are also at risk. Some of the occupations with high levels of asbestos exposure include U.S. Navy veterans, pipefitters, machinists, boilermakers, millwrights, masons, shipbuilders and forge men.
Mesothelioma is an incurable cancer, but fortunately it is fairly rare. Only about 3,000 people are diagnosed with it each year in the United States, and it causes approximately 20,000 fatalities worldwide annually. The cancer’s decades-long latency period, combined with the fact that asbestos’s peak usage occurred in the mid-20th Century, means that the highest rate of diagnosis is yet to come.