Idiopathic Mesothelioma
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]
- Children younger than the shortest known latency period have been diagnosed with mesothelioma. This means asbestos exposure in their lives would not yet have had time to cause this type of cancer, so the cause is unknown.[3]
- Almost all cases of the very rare pericardial mesothelioma and mesothelioma of the tunica vaginalis testis are spontaneous.[3]
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, while in others ongoing investigation uncovers a reason for the cancer. Researchers continue to study this rare cancer to try to solve the mystery of the idiopathic cases.
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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.
Other people with mesothelioma can find the source of asbestos exposure with investigation by an expert. For instance, some women whose husbands worked around asbestos were exposed through the fibers brought home on their clothing. Asbestos in a nearby plant or in an older home can also trigger exposure.
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.[4]
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.[4]
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.[5]
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 the cancer. This seems to indicate there is a genetic component to mesothelioma.[5]
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.[5]
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. In some people radiation therapy causes a secondary cancer, even mesothelioma.[6]
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.[6]
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.