Most people who have heard of malignant mesothelioma know of it as a lung disease that occurs in people who work or have worked with asbestos. While it is in most cases a rare form of cancer that grows in the layer of tissue covering the lungs, the layer of tissue known as the mesothelium actually covers most internal organs, and the mesothelium can develop cancer in places other than around the lungs, including the heart, the abdomen, and the testicles. According to the American Cancer Society, asbestosis is diagnosed in 2,000 to 3,000 people per year in the U.S.
It is a risk for anyone who works around asbestos fibers. When asbestos breaks apart, like when it is mined or when asbestos insulation is removed, the dust that is created may be inhaled (causing pleural mesothelioma) or swallowed (causing peritoneal mesothelioma). How the asbestos fibers cause the cell mutations that lead to cancer is not understood, but it may be the result of the asbestos irritating the tissues of the mesothelium.
Pleural (lung) mesothelioma causes symptoms such as painful breathing (also called pleurisy), shortness of breath, coughing, chest pain, weight loss, and lumps of tissue under the skin of the chest. When it attacks the mesothelium in the abdomen, a form of the disease known as peritoneal mesothelioma, symptoms include swelling of the abdomen, pain, altered bowel habits, weight loss, and lumps of tissue in the abdominal area. In the tissue layer over the heart, it can cause chest pain and difficulty breathing. Mesothelioma of the testicles is so rare that little information is available about the symptoms.
In addition to difficulty breathing, difficulty swallowing, and chest pain, it can put pressure on the superior vena cava, the large vein leading from the upper body to the heart and can press on the nerves and spinal cord, causing pain. It can also cause fluid to accumulate in the chest, compressing the lungs and making breathing labored. People who die of this disease are usually killed by complications like heart failure, lung failure, or stroke.
This disease is what is known as “dose-dependent,” which means that the longer you were exposed to asbestos, or the heavier the exposure to it, the greater the chances of developing it (whether of the lungs or another type). The dose dependency also affects the length of time between exposure and diagnosis, which can range from 10 to 50 years. Because even doctors sometimes have a hard time diagnosing mesothelioma, it is vital for anyone who has been exposed to asbestos to bring symptoms like shortness of breath to the attention of their doctor promptly. The earlier the diagnosis, the greater the survival rate.
The mesothelioma survival rates look particularly bleak because the disease is not usually diagnosed until it is advanced enough to cause symptoms. At that point, the treatment options are very limited. Generally speaking, from 7 to 20% of patients will survive for five years or more after being diagnosed. The average survival for someone with mesothelioma is between four and 18 months after being diagnosed. Symptoms can take as long as 50 years to develop after exposure to asbestos, so most people with mesothelioma don’t know that they have it.
Because of this, development of new tests and aids to earlier diagnosis are important areas of research into mesothelioma. The relatively recent Mesomark blood test is able to help some people be diagnosed earlier than they would otherwise, making more treatment options available and improving survival rates.
Treatment options include the traditional cancer treatments of surgery, radiation, and chemotherapy. Usually two or more of these treatment options will be combined. A number of clinical trials in the U.S. are showing promising results, particularly for those whose disease was diagnosed relatively early. In these cases, some clinical trials are showing survival rates of up to 40% as opposed to the 10% or so average mesothelioma survival rate.