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Mesothelioma Latency Period

Latency period for mesothelioma refers to the time between initial defined asbestos exposure and when a doctor is able to diagnose the disease. This period of time is one of the hallmarks of mesothelioma because it can be such a long time.

The typical mesothelioma latency period is 20 to 50 years, with recent studies finding a median of 30 to 45 years. The shortest possible latency period is 10 to 15 years, while the longest is more than 50 years. Because of this long time span and because most people are exposed to asbestos as young adults or older, most of those who are diagnosed with mesothelioma and other asbestos-related disease are in their 60s or 70. Those diagnoses come after symptoms of the disease – a persistent cough or difficulty breathing – become nagging or debilitating.

Studies show that lower exposure levels and shorter durations of exposure can lead to longer latency periods. Conversely, individuals with high levels of exposure for long periods of time have significantly shorter latency periods.

The latency period of mesothelioma typically continues until later stages of the disease, when symptoms finally begin and a doctor can diagnose the patient. At these later stages, the cancer is more difficult to treat and the patient generally has a shorter life expectancy. But a prompt diagnosis followed by immediate treatment can lead to an improved prognosis. Learn more about your treatment options by requesting a free informational packet from the Mesothelioma Center.

Factors Affecting Latency Period

Recent studies conflict on the matter of what affects latency period. Some researchers estimate that the latency period is longest for pleural mesothelioma, about 30 to 50 years, while latency period for other types typically falls between 20 and 40 years.

But one 2011 study reported a statistically insignificant difference in latency periods. In the study of 238 mesothelioma cases, researchers found a latency period of 49 years for pleural mesothelioma and 46 years for peritoneal mesothelioma.

The study also reported that women have an average latency period of 53 years, five years longer than men. The authors hypothesize that this is a result of overall lower exposure levels in women. Other studies similarly found that women have longer mean latency periods.

Latency Period and Dose-Response Relation

Exposure to extremely high levels of asbestos can lead to a shorter mesothelioma latency period, even if the duration of exposure is only a few months. Because of this, individuals at risk of having the shortest latency periods include first responders. Some paramedics, firefighters and police officers who worked immediately after the World Trade Center attacks and during Hurricane Katrina have already developed asbestos-related mesothelioma from short-term, high-level exposure.

One paramedic worked near the World Trade Center for several months after September 11, 2001. Although she had no other known exposure to the mineral, she died of mesothelioma less than five years later.

As years pass, medical experts expect to see an elevated amount of mesothelioma cases in first responders. Many of these new patients are expected to have abnormally short latency periods, putting them among the 1 percent of mesothelioma patients who receive a diagnosis within 15 years of initial exposure.

Like exposure to high levels of asbestos, exposure for longer periods of time can also shorten the expected latency period. Consequently, people with a history of heavy occupational exposure typically experience shorter-than-average latency periods. One study found that it was shortest in insulation workers, who experienced an average latency period of slightly less than 30 years.

Latency Period and Diagnosis

Symptoms of mesothelioma – such as shortness of breath, chest pain and fatigue – may not appear until the cancer is in later stages. Even after symptoms do appear, asbestos exposure may be overlooked as a factor. Because asbestos exposure occurred so long ago in most cases, many patients overlook it when considering possible causes of their illness. In most cases, this means an accurate diagnosis is delayed until after the cancer has spread beyond its original site.

The long latency period and delayed diagnosis contribute to a poor prognosis. Patients have the longest expected life spans when they are diagnosed in earlier stages of the disease. Treatments are more effective before cancer growth has spread, so an early treatment plan makes a greater impact in lengthening life span.

Increasing Latency Period?

Some mesothelioma researchers believe that the actual latency period of mesothelioma actually could be greater than the typical 20 to 50 years. In the past, an asbestos-exposed individual may have died of old age or unrelated health problems before mesothelioma had sufficient time to develop. But individuals are now outliving the life expectancy of decades past: life expectancy in the United States in 2003 was 78 years, nearly a decade more than the life expectancy of 40 years earlier.

This has resulted in a greater occurrence of the cancer in older individuals. From 1999 to 2008, 62 percent of new mesothelioma patients were 70 years or older. This raises the mean and median observed latency periods accordingly.

An older age at diagnosis does not have to mean a worse prognosis. Make an appointment with a mesothelioma specialist who can give you a second opinion and help you explore all your treatment options. To learn more about mesothelioma doctors and to find one in your area, visit our Doctor Match Program page.

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