Mesothelioma Latency Period

A mesothelioma diagnosis is a dreaded one. Of all cancers this is one of the most aggressive, most difficult to treat, hardest to cure, and with one of the shortest survival rates. Survival rates for it are low is because of its long latency period.

Latency is the time between the exposure that causes an illness and a definite diagnosis of that illness. For most people with mesothelioma that means the time between initial asbestos exposure and a firm diagnosis of the cancer. The latency period for mesothelioma is infamously long, which means many people are not diagnosed until this aggressive cancer has spread and is nearly impossible to cure.

Illness and Latency Period

The latency period is not unique to mesothelioma, although because it is notably long for this disease, the two are often connected. Any illness can have a latency period. When there is something that is known to cause an illness, the time between exposure to it and when a person gets diagnosed with the disease is latency.

This doesn’t mean that the illness is not developing or that it is inert in the person. In many cases the illness is progressing during this period, while the person who will eventually be diagnosed with it is not getting treatment and may even be continually exposed to what triggered the illness. This is true of mesothelioma. The cancer develops during the latency period, yet it shows few unique symptoms or only symptoms that seem like more common, less serious diseases.

Mesothelioma’s Latency Period

The latency period for mesothelioma is long compared to many diseases, including other types of cancer. It is typically between 20 and 50 years. In one study the latency periods in a group of people with mesothelioma ranged from 14 years to 72 years, which shows just how much diversity there is. In this same study the mean latency was found to be nearly 49 years, so longer is more likely. 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 the symptoms earlier, but they either were not severe enough to warrant a visit to the doctor or they were mistaken for symptoms of a more common illness. The symptoms that indicate a person may have mesothelioma include a persistent cough, trouble breathing, chest pains, and lumps under the skin of the chest. Once these become severe enough that a doctor runs tests for cancer, mesothelioma may be diagnosed.

What Affects Latency?

The latency period varies among individuals because of several factors, including occupation. One study looked at mean latency period categorized by occupation. From lowest to highest latency periods they were: insulators, dock workers, a group with mixed occupations, shipyard workers, and people with maritime careers of any type.

Career impacts latency, most likely because it effects how extensively a person was exposed to asbestos, how often, and for how long. 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 and some developed mesothelioma more quickly than usual.

Sex and age also affect the latency period for mesothelioma. One study found the mean highest latency period in women exposed to asbestos at home. 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 and unknowingly brought asbestos fibers home where women were exposed secondhand.

Age can impact latency. The older someone is at the time of initial asbestos exposure, the shorter the latency period, probably due to immune system function. Younger people have stronger immune systems and may be able to 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 not good, partly due to its unusually long latency period. Most people do not receive a diagnosis for the cancer until decades after the exposure to asbestos occurred. In the meantime that cancer develops and spreads. By the time a diagnosis is made it is often well advanced and difficult to treat, not to mention impossible to cure. If people exposed to asbestos were able to get diagnoses earlier they would likely have more positive prognoses.

Latency period is an important factor in any disease, but it is a major reason that few people survive mesothelioma. One study recently found that the latency period was actually increasing, which means that even fewer people have a chance of catching mesothelioma earlier and receiving a good prognosis.

Researchers are working on ways to detect the cancer earlier, but it remains a struggle. People who know they are exposed to asbestos can take steps to be proactive. These people should be aware of the risks, know the symptoms, and talk to their doctors about the possibility of early cancer screenings. The latency period puts people at a high risk for dying from mesothelioma, but with vigilance and good medical care it can be counteracted.