Idiopathic Mesothelioma
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Idiopathic mesothelioma is any case of mesothelioma with no known or certain cause. Also known as spontaneous mesothelioma, this occurs in about one person per million. In most cases of mesothelioma, the cause is past asbestos exposure, but sometimes the cause is unknown or may be related to other factors.
Facts About Idiopathic Mesothelioma
- Idiopathic does not mean a cause doesn’t exist, just that it can’t be determined with the evidence at hand.
- These cases may be triggered by asbestos exposure of which the patient was unaware or by another agent.
- Studies have found that patients with idiopathic pleural mesothelioma live longer than those with known asbestos exposure.[1]
- Only about half of patients with peritoneal mesothelioma, the cancer of the abdominal lining, have known asbestos exposure.[2]
- Idiopathic, also known as spontaneous mesothelioma, occurs in one per million people.[3]
- Idiopathic mesothelioma can be any of the three main types of mesothelioma: pleural, peritoneal, and pericardial.
- Prognosis and life expectancy are, on average, no different from mesothelioma with a known cause.
- As with other mesotheliomas, if caught early, outcomes are better for an idiopathic mesothelioma patient. There is still no cure.
How Can Idiopathic Mesothelioma Be Explained?
There may be many possible explanations for cases of diagnosed mesothelioma without asbestos exposure. In some instances, a cause is never found.
In others, the ongoing investigation uncovers a reason for cancer. Researchers continue to study this rare cancer to try to solve the mystery of the idiopathic cases.
Unknown Asbestos Exposure
For some people diagnosed with mesothelioma, asbestos exposure may be the cause even if they think they have not been around this mineral. In many cases, the source of exposure is obvious, usually a past workplace known to have contained asbestos.
There are a few ways someone might be exposed to asbestos without realizing it happened:
- Some women whose husbands worked around asbestos were exposed to the fibers brought home on their clothing.
- Another possibility is exposure through a person’s environment. Asbestos in a nearby plant or an older home can contaminate the air, soil, or water in the area, exposing people.
- Evidence has come to light in recent years that indicates many talcum powder products are contaminated with asbestos. Over years, the use of these hygiene products could lead to mesothelioma and other cancers.[4]
Erionite Exposure
Asbestos may not be the only mineral that causes asbestos after exposure. Erionite has also been shown to trigger mesothelioma. It is a type of mineral that has a similar fibrous structure. It is a type of zeolite mineral and has other properties that are like those of asbestos.[5]
Erionite is not used commercially, but because it is found naturally in the earth, exposure is possible. Mines operating for other minerals may disturb deposits, causing fibers to become airborne, for instance. It may also be a small part of zeolite minerals used in commercial products, including animal feed, pet litter, and wastewater treatment materials.[5]
Genetic Susceptibility
Many mutations in genes have been found in people that make them more susceptible to cancer, sometimes any cancer or sometimes a specific type. Genetic mutations may explain some idiopathic cases of mesothelioma.[6]
It is well known that although asbestos is the main risk factor and cause of mesothelioma, it is still rare. Most people exposed to asbestos never develop cancer. This seems to indicate there is a genetic component to mesothelioma.[6]
Simian Virus 40
Exposure to a virus known as SV40 may cause or be a factor in mesothelioma. Animal studies have found a direct connection, even causing mesothelioma in 100% of subjects in some cases. In humans, the link is not as clear. SV40 was first discovered as a contaminant in polio vaccines, so anyone who received that vaccine could have been exposed.[7]
Exposure to Radiation
Radiation therapy is an important treatment modality in many types of cancer. It involves high-energy beams that trigger damage and death in cancer cells. An unfortunate side effect of this is damage to healthy cells. At this point, it is unclear what the relationship is to radiation and then a diagnosis of mesothelioma at a later time.
In some people, radiation therapy causes secondary cancer, even mesothelioma.[8] It is possible the mesothelioma would have developed regardless, but the radiation could speed up this process.
Studies have found higher mesothelioma rates in people who have received radiation to parts of the body near mesothelial tissue. People working in the atomic energy sector also have higher rates of mesothelioma.[8]
For some people, the cause of their mesothelioma diagnosis will never be discovered, which is frustrating. For others, the known cause of negligent asbestos exposure is also frustrating. If you or someone you care about has been around asbestos, it is essential to be screened for mesothelioma and other cancers and respiratory illnesses. The earlier the diagnosis, regardless of cause, the better the prognosis.
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Anne Courtney has a Doctor of Nursing Practice degree and is an Advanced Oncology Certified Nurse Practitioner. She has years of oncology experience working with patients with malignant mesothelioma, as well as other types of cancer. Dr. Courtney currently works at University of Texas LIVESTRONG Cancer Institutes.