Mesothelioma Overview

There’s a good chance you have seen the television advertisements asking people to contact an attorney if they have mesothelioma. The reason for the requests is due to the fact that mesothelioma usually occurs as a result of exposure to certain substances in the work place or products used in the home, and people were not warned of the dangers. Mesothelioma is a rare form of cancer which affects the mesothelium, the thin tissue which lines many bodily organs.  Almost all cases of mesothelioma are caused by inhalation or contact with asbestos.1 In rare cases, mesothelioma can be caused by other factors including exposure to minerals similar to asbestos or irradiation. Though lung cancer is one of the most common forms of this disease, mesothelioma is not caused by smoking.

Asbestos is the name for a group of various fibrous minerals.  It has been used for thousands of years, but its peak usage wasn’t until the 19th to mid-20th century when asbestos was mined for use in insulation, ship building, flooring, drywall, and many other products.  When asbestos is inhaled or its fibers ingested, the material is absorbed into the body and eventually settles in the mesothelium.  There are two prevailing theories on how asbestos then results in mesothelioma.

Under the first theory, the asbestos fibers are believed to be attacked as invaders by the person’s immune system. The asbestos fibers are thought to be resistant to the immune attacks, and as a result, surrounding cells are damaged.  This damage eventually leads to the formation of cancerous cells.  Under the second theory, the asbestos fibers are the cause of mutations to the mesothelium cells, and the mutated cells eventually become cancer cells.

Prevalence of Mesothelioma

Every year, approximately 2 to 3 thousand new cases of Mesothelioma are diagnosed, accounting for about 3 out of every 1000 cancer diagnoses.  Patients diagnosed with mesothelioma are usually in their 60s.  The later age of mesothelioma patients is because the disease typically has a long latency period meaning it takes many years after the initial exposure to asbestos for the cancer cells to form.

In addition, the mesothelioma diagnosis is often difficult due to problems with tissue samples or cancer cells that mimic other types of cancers.2  It requires an experienced pathologist able to differentiate between cancer due to mesothelioma and other types of cell mutations.3 Most cases of mesothelioma occur among veterans, industrial workers and construction-related workers as they were often exposed to asbestos through their professions.  Since asbestos use has been banned in many countries and is declining in use worldwide, we can hope that the number of mesothelioma cases will decline in the future.

Types of Mesothelioma

There are four main types of mesothelioma:4

  • Pleural Mesothelioma is the most common type and occurs in the lungs and chest. This area of the body is most vulnerable to mesothelioma cancer because asbestos dust usually enters the body by inhalation during normal breathing.  About 70% of cases are pleural mesothelioma.
  • Peritoneal Mesothelioma is the next most common type of mesothelioma. It occurs in the abdominal cavity lining and in the coverings of the stomach, liver, pancreas and bowels.
  • Pericardial Mesothelioma occurs in the lining of the heart.  It represents about 5% of mesothelioma cases.
  • Testicular Mesothelioma is the rarest form of mesothelioma. It represents less than 1% of cases and occurs in the lining of the testicles. 

Mesothelioma Diagnosis and Prognosis

Unfortunately, there is currently a poor medical outlook or prognosis for mesothelioma patients, though hopefully that will change over time with continued research. Since there are few symptoms of mesothelioma in its early stages, it is usually not diagnosed until it has reached the more serious late stages.  When patients do begin to experience mesothelioma symptoms, they may mistake them for common ailments.

Doctors may also mistakenly associate symptoms with other common problems, particularly when the patient is elderly, and not test for mesothelioma. The most common symptoms of mesothelioma include: pain in abdominal area, breathlessness, weight loss, chest pains, loss of appetite, and dry cough.  The symptoms of mesothelioma will vary depending on the type of mesothelioma.

Like most cancers, mesothelioma is typically diagnosed with a body image scan (such as MRI, X-Ray, PET scan, or CT scan) and then confirmed with a biopsy.  If the mesothelioma is in its early stages, it can frequently be treated with surgery alone.  In later stages, chemotherapy and/or radiation are most commonly used to treat mesothelioma. Today’s mesothelioma patients have a much better outlook than patients who were diagnosed in the past due to greater awareness of the disease and advances in technology used for diagnosis.

In addition, medical professionals know more about mesothelioma, and there have been medical breakthroughs in treatments that include more effective chemotherapy drugs.  There have also been many advances in treating problems associated with cancer treatments, like pain management strategies.  Life expectancy of mesothelioma patients is about a year after diagnosis.  However, this prognosis varies considerably depending on n factors such as the stage of the cancer, the patient’s health, and the route of treatment.

References

1 Sheaff, Michael T., Steele, J. P. C. and Klabatsa, A. (2007) Pleura and Peritoneum. The Cancer Handbook.

2 Ibid

3 Kao, S. C.-H., Reid, G., Lee, K., Vardy, J., Clarke, S. and Van Zandwijk, N. (2010), Malignant mesothelioma. Internal Medicine Journal, 40: 742–750.

4 Giaccone, G. and Baas, P. (2006) Mesotheliomas, in Textbook of Uncommon Cancer, Third Edition (eds D. Raghavan, M. L. Brecher, D. H. Johnson, N. J. Meropol, P. L. Moots, P. G. Rose and I. A. Mayer), John Wiley & Sons, Ltd, Chichester, UK, Chapter 23.