Glossary

Asbestos is a silicate mineral that commonly occurs in nature. Unlike typical silicates, however, the molecular structure of asbestos is fibrous; that is, its atoms are arranged in long, thin molecules that resemble threads.

The threadlike nature of asbestos gives it a number of unusual properties, the most useful of which is that it can be spun, woven, and used to make a fabric. In this form, the mineral nature of asbestos is combined with the flexibility and utility of cloth, making it an ideal material for use in construction.

As a mineral, asbestos is tough, nonreactive, and an excellent insulator against heat and electrical current; it is also fireproof. This makes asbestos an ideal insulating and protective covering for piping, machinery, and all types of industrial equipment. It was once also widely used in the walls, floors, and ceilings of buildings; in the making of boilers, power plants and ship engines, in fireproof clothing and other materials; and in appliances.

Unfortunately, asbestos is toxic. When flexed or otherwise disturbed, the crystalline threads of asbestos shatter, releasing billions of microscopic shards into the air as dust. When inhaled, these tiny, razor-sharp “dust particles” slice through the lung wall and into the cells of the mesothelium, where they mutate the mesothelial cells and turn them cancerous.

This ability of asbestos to trigger mesothelioma is the reason for the near-ban on asbestos starting in the 1970s – and for the large number of workers with mesothelioma today.

Mesothelioma means “cancer of the mesothelium”. The mesothelium is a membrane that lines the inside of certain body cavities: the pleura (chest cavity), the peritoneum (abdominal cavity) and pericardium (sac surrounding the heart). It also envelops the internal reproductive organs in both men and women. The mesothelium covers and protects the internal organs of the body. It is composed of a thin layer of mesothelial cells that produce a slick, protective lubricating fluid that cushions the organs and allows them to slide over and around each other as necessary.

Malignancy is another word for cancer. Cancer is the condition in which the natural process of programmed death (apoptosis) within living cells is halted and replaced by a process of uncontrolled growth. As the now-immortal cell grows, it divides again and again far beyond the normal limit, creating a lump of tissue called a neoplasm or tumor. These tumors cause harm in two ways: by growing on, over, and into neighboring tissues and organs, damaging them and disrupting their function (invasion); and by spreading to other locations in the body via lymph or blood (metastasis).

Mesothelioma is a malignancy of the mesothelium. When asbestos fibers are inhaled, the tiny, razor-sharp crystals sink into and through the walls of the lung, stabbing into and piercing the cells of the mesothelium. Since asbestos is rock, the body’s natural hunter-killer cells cannot digest and remove the asbestos crystals as they enter the mesothelium – and once inside, the fibers interact with the DNA of the mesothelial cells, “hacking” their cellular programming and turning them into malignant cells.

Soon tumors begin to form and spread; when these become widespread enough to interfere with body functions, the symptoms of mesothelioma appear.

Mesothelioma is in incurable disease. Since it cannot be cured, its progress can only be managed in order to give the patient the longest and highest-quality life during the time remaining to them. This process is called staging. Staging is the process of characterizing the patient’s condition based upon the spread and locations of the cancer within their body and designing a treatment based upon this characterization.

Three staging systems exist for the management of pleural mesothelioma: the Butchart System, the TNM System (Tumor-Node-Metastasis), and the Brigham System. Each of these staging systems has its strengths and weaknesses, and a given case may be staged in terms of more than one system.

Using these systems, doctors can determine how much time the patient has remaining, which treatments (if any) will allow him or her to extend that time, and the best methods by which to manage pain and loss of function as the disease progresses.