Mesothelioma: Asbestos Exposure Continues to Cause Cancer

According to the National Cancer Institute, an estimated 1,735,350 new cases of cancer were diagnosed in 2018, and this number is expected to continue to grow in 2019. This staggering number includes hundreds of cancer types, but one type that often gets lost among these cancers is mesothelioma, which is a rare type of cancer that primarily affects the lining of the lungs but can also be found in the abdomen and heart.

Nearly 3,000 new cases of mesothelioma are diagnosed each year in the United States, and the only known cause of this type of cancer is exposure to asbestos. Because asbestos is still used today around the world, people will continue to be diagnosed with mesothelioma until there is a complete ban of this deadly carcinogen.

For now, a ban in the United States or globally is not likely, and therefore the most effective way to prevent this cancer is through increased awareness.

The Long History of Asbestos Use

Asbestos use has been widespread across the world and in the United States for centuries. Because of its properties of flame retardancy and sound absorption, asbestos became a mineral of choice for many materials, from housing insulation to automobile brake pads. Before our knowledge of its carcinogenic properties, asbestos was considered revolutionary as a result of its many positive uses.

Asbestos is a catch-all term that encompasses 6 types of naturally existing mineral silicates, including actinolite, amosite, anthophyllite, chrysotile, crocidolite, and tremolite. The type that we hear most often about is chrysotile, which accounts for 90% to 95% of all asbestos that remains in buildings and homes in the United States.

Asbestos is a naturally occurring mineral made of microscopic fibers that become a serious threat when airborne. These airborne fibers can be inhaled or ingested, and because they are not visible, exposure is typically unnoticed.

These microscopic, needlelike fibers cling to the surrounding tissues of our internal organs, where they lie dormant for prolonged periods. These fibers are extremely small and durable, making our bodies unable to break down and expel them, eventually leading to scarring of our internal organs and the development of tumors.

Since 1999, more than 45,000 deaths occurred from mesothelioma in the United States, according to the Centers for Disease Control and Prevention. Although regulations have become stricter regarding asbestos, and how it can be used, the Environmental Protection Agency (EPA) has yet to ban this deadly carcinogen, although it came close to a full ban in 1989. As of April 2019, the EPA further tightened the use of asbestos in certain industries, with a new iteration of the Significant New Use Rule; however, this still leaves loopholes for potential exposure.

Who Is at Risk?

The symptoms of a serious asbestos-related disease, such as mesothelioma, do not present immediately after exposure. Most people exposed to asbestos will not be diagnosed with mesothelioma until 10 to 50 years later.

Being aware of the threats of asbestos exposure can make a difference for those who are prone to being exposed. Men and women who are in occupational fields such as contracting, firefighting, construction, engineering, and military are all at an increased risk of exposure, because through such occupations they may come in contact with common materials that contain asbestos.

For those in the construction industry, homes built before 1980 are likely to be harboring some form of asbestos-containing materials. If asbestos has not been removed, these people could be in harm’s way.

Firefighters may also be exposed to asbestos when fighting a fire that releases asbestos-containing materials into the air. And although most of the exposure people face today is through materials in their own homes, military veterans might have also been exposed through the materials used to build naval ships and sleeping barracks.

A Difficult Diagnosis

Every year, only a few thousand Americans are diagnosed with mesothelioma, a number that is much smaller than for more common types of cancer, which make this cancer off the radar in most cancer-related discussions. This does not diminish the fact of how damaging this cancer is for those who are affected, because mesothelioma is a rapidly developing cancer. That is, once diagnosed, mesothelioma typically develops quickly because it is usually diagnosed at such a late stage.

Because symptoms don’t arise for a long period after exposure, and they mimic symptoms of more common diseases, this cancer is often diagnosed at a late and aggressive stage. The vague symptoms that are associated with mesothelioma include:  

• Abdominal pain
• Coughing
• Difficulty swallowing
• Muscle weakness
• Unexplained weight loss.

As in many cancer types, the key to an improved prognosis (survival) is early diagnosis. This is why getting screened regularly, with CT scans or chest x-ray, is very important, especially if you are at risk of exposure because of your line of work.

The 3 Types

Mesothelioma has 3 different types, each affecting different areas of the body:

• Pleural mesothelioma affects the lining of the lungs, and makes up most of the cases of mesothelioma diagnoses
• Peritoneal mesothelioma is diagnosed in the lining of the stomach
• Pericardial mesothelioma affects the lining of the heart

The prognosis of someone who is diagnosed with pleural mesothelioma, which is the type that affects the lungs, is typically less than 1 year. Peritoneal mesothelioma and pericardial mesothelioma are less common than pleural mesothelioma, with pericardial mesothelioma often being diagnosed just before death.

Treatment Options

To date, there is no cure for mesothelioma, and the treatment options are very limited, often involving palliative care that is focused on comfort and improved quality of life rather than on treating the cancer itself. This is particularly disheartening, because mesothelioma is one of the few types of cancer that can be easily prevented and does not have a genetic connection.

Patients who are diagnosed with mesothelioma may feel a sense of guilt, because of the potential negligence in being exposed to asbestos; however, it is difficult to be certain of when and where exactly they had contact with asbestos fibers.

Research for this type of cancer does not receive as much funding as better-known cancers. As noted, earlier diagnosis increases the chance of achieving disease remission, especially in the case of pleural mesothelioma.

Surgery may involve the removal of certain tissues or lymph nodes, but a more invasive procedure called “extrapleural pneumonectomy” is the most effective treatment for this cancer. In extrapleural pneumonectomy, the affected lung is removed, which is a difficult procedure for the patient, during and after it is complete.

The new type of immunotherapy known as CAR T-cell therapy is effective in treating several types of cancer, mostly in blood cancers so far. Mesothelioma is a solid tumor (like breast, prostate, or lung cancer), and the use of CAR T-cell therapy in mesothelioma is still in its infancy, but joining a clinical trial is becoming more readily available to those who have exhausted all other treatment options, and may offer opportunity to try new treatments.

Spreading Awareness

Everyone should be cognizant of the dangers associated with asbestos exposure. By educating people about this human carcinogen and spreading the information, there is hope that the incidence of mesothelioma will decrease.

Until there is a full asbestos ban, we must all stay diligent about avoiding exposure to asbestos and continue to push for the EPA (as well as international bodies) to pass legislation to protect people from such exposure.