About Mesothelioma

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Written by Chrystal Moulton, BS. This article covers the basic facts about mesothelioma.

Mesothelioma is a rare cancer resulting mainly from exposure to asbestos or asbestos-like materials. In the United States, mesothelioma accounts for 3% of cancers or approximately 2,000-3,000 cases per year. (1, 2) In this article, we will get a general overview on the types of mesothelioma, symptoms related to each type as well as the various treatment options and current research available.

What is the Mesothelium?

The mesothelium is a very thin lining that surrounds the internal organs and the cavities in which they are housed. In the case of mesothelioma, the tumor develops on the lining surrounding the internal organs or body cavities. The corresponding name given to different kinds of mesothelioma depends on the location of the lining where the tumor is present. (1, 2) For example, pleural mesothelioma is in reference to a cancerous tumor in the lining of the lung or lung cavity. The word “pleura” refers to the lung. Below is a list of some common types of mesothelioma:

  • Pleural mesothelioma- cancer of the lining around the lung and/or lung cavity
  • Peritoneal mesothelioma- cancer of the lining around the abdomen and/or abdominal cavity
  • Pericardial mesothelioma- cancer of the lining surrounding the heart also known as the “heart sac”
  • Testicular mesothelioma- cancer of the lining surrounding the reproductive organs. This is the rarest form of mesothelioma.

These various types of mesothelioma are also associated with different cell types that form the tumors (1, 2). The four different cell types that make up the tumor in mesothelioma are:

  • Epithelioid- cells in the tumor resemble epithelial cells. Tumorous growth is well organized; cells are almost square in shape, flat, and contains a nucleus.
  • Sarcomatoid- tumorous growth is made up of irregular shaped cells that grow in a disorganized pattern. Cells in this form lack a nucleus.
  • Biphasic- tumorous growth is made up of a mixture of epithelioid and sarcomatoid cell types; growth pattern is also disorganized.
  • Desmoplastic- a variant of sarcomatoid cell type that is extremely hard to distinguish from healthy tissue.

Diagnosis of Mesothelioma

Diagnosing mesothelioma is a very difficult process that can and should be done only by those who specialize in this form of cancer. Time between exposure to asbestos and appearance of mesothelioma (called the latency period) ranges between 30-60 years. (3) Specific biomarkers exist that correlate to various types of mesothelioma. (4, 5) However, these biomarkers, by themselves, are not enough to make a diagnosis. Imaging with the use of a CT scan, PET scan, MRI, or chest x-ray is usually done to determine abnormal growths and/or appearances of the organs that may be affected. Samples of tissue or fluids are also usually gathered to determine the presence of cancer cells, asbestos, or other asbestos-like materials that may contribute to the development of mesothelioma. (4)

Symptoms and Prognosis of Types of Mesothelioma

In general, the outlook in patients with mesothelioma is poor. Due to the rarity of the disease, the length of time between exposure and appearance of the cancer, and the lack of definitive diagnostic tools, diagnosing mesothelioma is especially difficult. In some cases, once the cancer is identified it usually has progressed beyond the beneficial effects of certain treatments. (1-5) Symptoms vary based on the type of mesothelioma presented. See table below for details.

Symptoms related to specific types of Mesothelioma (1)

Treatments Available

Following diagnosis, patients follow the conventional route of cancer treatment. This includes surgery, chemotherapy, and radiation therapy. (1-3) Different therapies are applied based on the stage of the cancer present. Not everyone may qualify for all three forms of conventional treatment. Photodynamic treatment, which uses light to kill cancer cells, has been effective in treating skin cancer and some forms of lung cancer including pleural mesothelioma. This therapy is specifically effective on localized pleural mesothelioma. Another more experimental form of therapy known as gene therapy and immunotherapy is performed mainly under clinical trials. Gene therapy is used in addition to chemotherapy to kill the cancer cells. Researchers treat patients with a non-infectious virus that forces cancer cells to produce proteins making them susceptible chemotherapeutic drugs. This form of gene therapy is called “suicide gene therapy”. Immunotherapy is also used to boost the immune system response to cancer. (1, 2) [Clinical trials for mesothelioma]

Patients often also seek alternative treatments in addition to conventional treatment in hopes enhancing treatment effects or managing pain. This includes acupuncture, massage therapy, and aromatherapy. [Research experimental therapies in mesothelioma]

Individuals Exposed to Asbestos

Use of asbestos has not completely stopped even in United States contrary to popular belief. Certain trades are uniquely exposed to asbestos since under law it can be used if there is no suitable alternative found. Professions where there is a risk of exposure to asbestos include (1, 2):

  • Aerospace/aeronautical engineering
  • Aircraft mechanics
  • Auto plant workers
  • Auto mechanics
  • Appliance installers
  • Boilermakers and boiler/engine room workers
  • Construction workers: Bricklayers, carpenters, bulldozer operators, cabinetmakers, etc.
  • Chemical plant workers
  • Civil Engineers
  • Custodians
  • Electrical engineers
  • Electricians
  • Electrical linemen & cable men
  • Firefighters
  • Individual making heat resistant materials i.e. forge men, furnace makers, smelters, & pourers
  • HVAC mechanics
  • Industrial engineers
  • Insulation installers
  • Shipyard workers
  • Oil refinery workers
  • Plumbers
  • Railroad workers

To see a comprehensive list of professions at risk of asbestos exposure visit: http://www.asbestos.com/occupations/

Overall, despite the poor outlook for patients with mesothelioma, clinical research is being done to find effective tools to combat the disease. Individuals with this form of cancer can find support from the Mesothelioma Center as well as other foundations, hospitals, or support groups within the area that specialize in the treatment and litigation of mesothelioma. Also, in 2008, a social security program called Compassionate Allowances was created to allow individuals with rare diseases such as mesothelioma to receive some compensation. (1) As with any disease, early detection is key to successful treatment. Be sure to seek out resources specific to mesothelioma If you or someone you know has the disease.

Posted May 21, 2015.

References:

  1. Asbestos.com
  2. Mesothelioma.com
  3. Neumann V, et al. Malignant pleural mesothelioma: incidence, etiology, diagnosis, treatment, and occupational health. Dtsch Arztebl Int. 2013 May;110(18):319-26.
  4. Husain AN et al. Guidelines for pathologic diagnosis of malignant mesothelioma: 2012 update of the consensus statement from the International Mesothelioma Interest Group. Arch Pathol Lab Med. 2013 May;137(5):647-67.
  5. Ascoli, Valeria. (2015). Pathologic diagnosis of malignant mesothelioma: chronological prospect and advent of recommendations and guidelines. Annali dell’Istituto Superiore di Sanità, 51(1), 52-59.

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