The latency period for mesothelioma starts when a person is exposed to asbestos.
On average, it takes 30 – 45 years before mesothelioma symptoms develop.
A number of factors can impact the latency period experienced by an individual.
Delayed onset of symptoms is the biggest reason mesothelioma has a poor prognosis.
Generally, latency period is the time frame before symptoms appear after being exposed to any disease-causing agent. A disease-causing agent can be a virus, bacteria, or in the case of mesothelioma, asbestos. The hallmark of mesothelioma is the long period of time between exposure to asbestos and the diagnosis of actual cancer.
For most illnesses, a latency period ends when symptoms arise. While some experts use this definition for mesothelioma latency period, most agree this disease is latent until time of diagnosis.
The latency period for mesothelioma can be anywhere from 20 to 50 years, while recent data reports a median latency period anywhere from 30 to 45 years. The shortest reported latency period is 10 to 15 years, with the longest reported as more than 50 years.
Factors Affecting Latency Period
Each mesothelioma patient’s latency period will differ based on a number of factors, including type and duration of asbestos exposure, age, and occupation.
Asbestos is one of the most common occupational cancer-causing agents. However, it takes a long time before it scars and mutates the tissue it settles in, which then leads to mesothelioma. The following three factors regarding asbestos exposure further affect the amount of time it takes for mesothelioma to develop.
Duration of Asbestos Exposure
The longer someone is exposed to asbestos, the more fibers that are inhaled into the body. This increases the risk of developing mesothelioma. The longer someone is exposed, the shorter their latency period is likely to be.
Frequency and Concentration of Exposure
How often the exposure occurs and the amount of asbestos both impact latency period. For instance, continuous inhaling or ingesting of large amounts of asbestos will lead to shorter latency periods.
Type of Asbestos
The term asbestos encompasses several different types of naturally occurring cancer-causing minerals, including chrysotile, amosite, crocidolite, tremolite, anthophyllite, and actinolite. The most deadly is crocidolite asbestos, which may cause shorter latency periods, while it takes more exposure to chrysotile than others to develop mesothelioma.
There are a number of occupations that put individuals at risk of asbestos exposure. Some of the most common high-risk occupations are industrial workers, miners, insulation workers, and firefighters. Occupational exposure often correlates with shorter latency periods, given that exposure is consistent.
According to researchers, the older an individual is when exposed to asbestos, the shorter the latency period is likely to be. This may be due to the natural decline of the immune system over time. Thus, any exposure that occurs at an older age may make it more difficult for that person’s body to fight the damage caused by asbestos fibers, leading to shorter latency periods.
While there has been speculation that gender also plays a role since women have been found to have longer latency periods, this is likely because they have not had the same exposure rates as men. Historically, men have worked in high risk occupations, and many cases of mesothelioma in women were caused by secondhand exposure to asbestos when handling their family members’ work clothes.
Latency Period, Diagnosis and Prognosis
One of the reasons why mesothelioma is so difficult to diagnose is the long latency period. When asbestos fibers are inhaled, they lodge themselves in the lining of the lungs or abdomen, causing scarring and inflammation. It takes a long time, but this ultimately leads to cell mutation and tumor growth.
Symptoms, however, do not generally appear until the disease is in much later stages, generally stage III. When symptoms do appear, they are often attributed to more common illnesses, delaying an accurate diagnosis.
Delayed onset of symptoms and the long latency period are the main causes of a poor prognosis. It is highly recommended that patients seek a second opinion from a mesothelioma specialist, who can create the most effective treatment plan.