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Receiving a mesothelioma diagnosis can feel like the end of the world. Of all cancers, mesothelioma is one of the most aggressive and difficult to treat. Mesothelioma is also difficult to cure, and survival rates are very low because of its long latency period.
Latency is the time between the exposure that causes an illness and the development of symptoms and a firm diagnosis. Mesothelioma has a notoriously long latency period. For many, this means they are not properly diagnosed until this aggressive cancer has spread and is nearly impossible to cure.
Illness and Latency Period
A long latency period is not unique to mesothelioma. Any illness can have a latency period. When there is a known cause for an illness, the time between exposure and a diagnosis of the disease is latency.
Latency does not mean the illness is not developing. In many cases, the illness is progressing during this period. The person may still be exposed to the trigger during this period. This is true of mesothelioma. The cancer develops during the latency period, yet shows few symptoms for years.
Mesothelioma’s Latency Period
The latency period for mesothelioma is typically between 20 and 50 years. This is long compared to many diseases, including other types of cancer. In one study the latency periods in a group of people with mesothelioma ranged from 14 years to 72 years. This proves just how much diversity there is. In this same study, the mean latency was nearly 49 years. This means a longer latency is more common. Other studies have found similar results.
The Emergence of Symptoms
Symptoms of mesothelioma often don’t become apparent until later in life. Someone may have experienced earlier symptoms, but they may not have been serious enough to warrant a visit to the doctor. These early symptoms may also have been mistaken for common illnesses. Common symptoms of mesothelioma include persistent cough, difficulty breathing, chest pains, and lumps under the skin of the chest. Once these become severe, a doctor visit may result in tests for cancer and a mesothelioma diagnosis.
What Affects Latency?
The latency period of mesothelioma varies among individuals due to several factors. One study examined mean latency period categorized by occupation. Occupations listed from lowest to highest latency periods were: insulators, dock workers, a group with mixed occupations, shipyard workers, and people with maritime careers.
Career impacts latency because it affects how extensively a person was exposed to asbestos. The dose-response, or extent of exposure, is another important factor affecting latency. The higher the level of exposure, the shorter the latency period is likely to be. This can be true even if the overall duration of exposure is low. As an example, workers at the World Trade Center in 2001 were exposed to large amounts of asbestos over a short period of time. This resulted in some people developing mesothelioma more quickly than usual.
Sex and age also affect the latency period for mesothelioma. The latency period for women is longer, with a mean of 53 years, compared to 47 or 48 for men. This may be related to primary and secondary exposure. Most men with mesothelioma were exposed on the job. In contrast, most women were exposed through secondhand exposure, inhaling fibers their husbands or fathers brought home on their clothing and shoes.
Age can also impact latency. The older someone is at the time of initial asbestos exposure, the shorter the latency period. This is probably due to immune system function. Typically, younger people have stronger immune systems and may hold off the negative impact of asbestos fibers longer than those who are older.
The Latency Period and Prognosis
The prognosis for many people diagnosed with mesothelioma is usually poor. This is partly due to the unusually long latency period of the disease. Most people do not receive a diagnosis until decades after their asbestos exposure. In the meantime, mesothelioma develops and spreads. By the time a diagnosis is made, it is often well advanced and difficult to treat. If people exposed to asbestos were diagnosed earlier, they would likely have more positive prognoses.
Latency period is an important factor in any disease but is a major reason few people survive mesothelioma. One study recently found the latency period for mesothelioma was actually increasing. This means even fewer people have a chance of catching mesothelioma early and receiving a good prognosis.
Researchers are working on early detection methods, but it remains a struggle. If you know you have been exposed to asbestos, take proactive steps. These people should be aware of the risks, know the symptoms, and talk to their doctors about early cancer screenings. The latency period puts people at a high risk for dying from mesothelioma. However, with vigilance and good medical care, it can be counteracted.
Page Medically Reviewed and Edited by Anne Courtney, AOCNP, DNP
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.