Malignant mesothelioma is a form of cancer. It is an asbestos-related disease that develops in the lining around the lungs. Up until recent years it was extremely rare. More cases are diagnosed now, because malignant mesothelioma is caused by exposure to asbestos, and doesn’t result in mesothelioma symptoms for several decades. Hence, people who were exposed to asbestos in the 1970s, the 1960s, and even the 1950s and earlier are only just now being diagnosed with the disease.
Mesothelioma comes in several forms, and is not always found in the lung lining (pleural mesothelioma). Peritoneal mesothelioma develops in the lining over the abdominal organs, and pericardial mesothelioma develops in the membrane surrounding the heart.
Malignant mesothelioma is further classified by the type of cancer cells found in the tumor. Epithelial cell mesothelioma is the most common type. The second most common type is a tumor with both epithelial mesothelioma cells and sarcomatoid mesothelioma cells. The rarest type of malignant mesothelioma with respect to cell type is pure sarcomatoid mesothelioma.
One of the problems with the mesothelioma diagnosis is that it can closely resemble other types of cancer, particularly a type of cancer called adenocarcinoma. Often it takes pathologists with experience in diagnosing mesothelioma to make a definitive diagnosis when it comes to distinguishing mesothelioma from adenocarcinoma.
How does asbestos cause malignant mesothelioma?
Asbestos has been used since ancient times, when the Chinese made “miraculous” garments woven from asbestos that could be cleaned just by exposing them to fire. Asbestos is a silicate mineral that is formed of long, thin crystals. The use of asbestos jumped with the coming of the industrial revolution in the mid 19th century. It was fireproof, soundproof, and could easily be mixed in with other materials like concrete. The first documented death that was attributed to asbestos was in 1906. It was around that time that researchers started noticing increasing numbers of untimely deaths in towns where asbestos was mined.
“Asbestosis” was first officially diagnosed in Britain in 1924. In the 1930s, the UK started regulating ventilation for asbestos mining. In 1931 the word “mesothelioma” was first published in medical literature, and its connection to asbestos exposure was noted in the 1940s. The U.S. government and the asbestos industry were criticized for not informing the public of the dangers of asbestos quickly enough, and did not act to reduce exposure to asbestos. It was not until the 1970s that proof was obtained that the asbestos industry had known of the dangers since the 1930s and had not made these hazards public.
The asbestos that causes malignant mesothelioma is “friable,” which means that it is crumbly enough that it can be crushed between the fingers. Once asbestos fibers are inhaled, they spend years breaking into even smaller crystals. Eventually working their way to the mesothelium, they cause a local irritation that in many cases turns into malignant mesothelioma after several years or even decades.
Mesothelioma Treatments and Prognosis
Malignant mesothelioma is mainly treated by the standard methods of treating cancer: with radiation, surgery, and chemotherapy or some combination of the three. Newer treatments are aimed at recruiting the patient’s own immune system to fight the cancer, and these immunotherapy treatments have shown promise. There are currently many clinical trials that malignant mesothelioma patients can participate in that are designed to develop new treatments.
The mesothelioma survival rate is not good. Most people diagnosed with mesothelioma do not live longer than a year or so after their mesothelioma diagnosis. However, there have been several cases of mesothelioma patients defying the odds and living with the disease for a decade or longer. One of the reasons that the mesothelioma survival rate is low is that the disease does not usually cause symptoms until it is fairly advanced.
People who, for whatever reason, are diagnosed at an earlier stage of the disease, respond much better to treatment. Therefore, there is also research going on to develop diagnostic tools that can diagnose mesothelioma at an earlier stage.
Anyone who has been exposed to asbestos in the workplace should notify their primary care physician of this fact. If mesothelioma symptoms do show up (or if an early diagnostic test is developed), the diagnosis may be quicker. As it is now, it takes an average of three to six months for the average malignant mesothelioma patient to be properly diagnosed.