If you have watched TV, listened to the radio, or consumed media of virtually any kind, then you have probably heard of mesothelioma at some point. You’ve also probably asked yourself “what is mesothelioma?” Indeed, even though it is mentioned frequently in advertisements, the disease itself is relatively not well-known.

A basic answer to the question is that mesothelioma is a type of cancer that forms in the lining of a variety of organs (most commonly the lungs) and is caused by exposure to asbestos. But there’s a lot more to the mesothelioma definition than that. Below, you’ll find a rundown of everything you need to understand mesothelioma thoroughly.


There is no real way to sugarcoat the destructive nature of mesothelioma. It is an aggressive disease that rarely gets caught early enough in its life cycle to make much of a difference for those affected.

For most patients, the prognosis is bleak with many only surviving a year or two after diagnosis. A mere 9 percent of mesothelioma patients will live 5 or more years after diagnosis.

Still, there are many factors that determine life expectancy and survival rate once someone is diagnosed with the disease.

These include:

  • Age
  • Gender
  • Stage of disease
  • Where the disease develops in the body
  • Cell type
  • Lifestyle and general health
  • Blood counts
  • Genetics

Age and gender are usually the most salient predictors of a patient’s outcome. Obviously, a young person is more likely to survive longer than an elderly person. Studies have also shown that women survive an average of 5 to 6 months longer than men.

Additionally, patients with mesothelioma that is caught in the initial stages will have a longer life expectancy than those who were diagnosed with a later stage of the disease.

We’ll discuss the different locations and types of mesothelioma later on, but the two main types of the disease—pleural (which forms in the lining of the lungs) and peritoneal (which forms in the lining of the abdomen)—can also determine survival rates.

For instance, those with the pleural form of the illness have survival rates of 73% after one year and 23% after three years. Peritoneal mesothelioma sufferers, on the other hand, have survival rates of 92% after one year and 74% after three years.

Surviving for a long period of time after diagnosis is rare, but still possible. A cure for mesothelioma does not exist, but a small number of patients have experienced complete remission. New treatment options are also constantly being researched, meaning that no case is a 100% lost cause.

The best ways to improve a mesothelioma prognosis are:

  • Seeking out a mesothelioma specialist
  • Exhausting your treatment options
  • Joining clinical trials
  • Making healthy lifestyle choices
  • Looking for second opinions


Any mesothelioma overview would be incomplete without discussing the different types of the disease. Mesothelioma is categorized by both its location in the body and its cell type.

These location types are:

  • Pleural (affecting the lining of the lungs)
  • Peritoneal (affecting the lining of the abdominal cavity)
  • Pericardial (affecting the lining of the heart)
  • Testicular (affecting the membrane surrounding the testes)

The two most common location types of the disease are pleural and peritoneal. Pleural mesothelioma accounts for between 70 and 90% of all mesothelioma cases while peritoneal generally accounts for the remainder. Only about 1% of all cases are pericardial, and testicular mesothelioma cases account for a tiny fraction of that.

Although pleural mesothelioma is the most common, it is still very hard to diagnose and often isn’t caught until the later stages of development. Patients generally survive an average of 17 months after diagnosis. Symptoms usually include constant chest pain and fever. Peritoneal mesothelioma spreads to organs in the abdominal cavity (e.g. liver, spleen, intestines, etc.) but has a slightly better prognosis than the pleural variety because of the advent of new treatment options. Its early symptoms include persistent nausea and abdominal pain.

Both pericardial and testicular forms of the disease are very rare. In many cases, the incidence of pericardial mesothelioma isn’t known until after a patient has passed. Symptoms often present as signs of a heart attack. Less is known about the testicular form of the disease because only around 100 known diagnoses have been recorded.

Mesothelioma is also differentiated by its cell type. To determine the cell type, doctors must perform a biopsy of the affected tissue.

Cell types include:


This is the most common cell type with the best prognosis. It is commonly found in pleural mesothelioma cases.


This is the second-most common cell type. It is generally considered the most aggressive cell type with the worst prognosis. It can be found in both pleural and peritoneal cases.


This is the least common cell type and is a combination of epithelioid and sarcomatoid cells. Prognoses depend on the amount of each cell present in the mesothelioma (i.e. a higher concentration of sarcomatoid cells will likely produce a more negative prognosis).

Mesothelioma tumors can also be classified as either benign or malignant. An overwhelming majority of mesothelioma cases are malignant, meaning that they are cancerous and more likely to spread to other organs. Fewer than 200 cases of mesothelioma have been benign. Benign tumors will not spread to other organs and can be surgically removed with little to no recurrence.


Questions like “what is mesothelioma?” or “how did I get mesothelioma?” will probably race through your head if you are ever diagnosed with disease.

For most if its development, mesothelioma is a silent illness. In fact, it usually takes between 30 and 40 years from the time a patient was first exposed to asbestos (the agent that causes mesothelioma) to the time their first symptoms begin to appear. This period of time is referred to as the “latency period.”

After symptoms start appearing, doctors will generally look to diagnose the problem in three ways:

  • Imaging scans
  • Blood tests and biomarkers
  • Biopsies

Imaging scans are usually a doctor’s first course of action because of their non-invasive nature. While they cannot provide a definitive mesothelioma diagnosis, imaging scans are nevertheless an important first step in determining if an issue is present.

Common options include:

  • X-ray
  • MRI
  • CT-Scan
  • PET Scan

The next option is to simply look at your blood. Certain blood tests can reveal an abnormal amount of substances in the bloodstream that may indicate the existence of mesothelioma. For instance, healthy mesothelial cells produce a certain amount of a substance called mesothelin that enters the bloodstream. A large increase of mesothelin in the blood could be an indication of mesothelioma. This is just one example of a mesothelioma “biomarker.”

Biomarker tests are often referred to as “assays” and can also be used to rule out certain diseases. Again, these tests cannot yet provide a definitive diagnosis for mesothelioma.

Some common biomarker assays include:

  • Mesomark (a test that checks mesothelin levels and, specifically, soluble mesothelin-related peptides)
  • Osteopontin
  • N-ERC/Mesothelin
  • Fibulin-3

The third option for diagnosing mesothelioma is really the only one that can prove the existence of the disease in a patient: biopsies. A biopsy gives the doctor a sample of the affected tissue that they can then test for mesothelioma. Pathologists look at the cell type that is active in the tissue sample. They can then recommend treatment and provide an accurate life expectancy for the patient.

There are three different methods doctors use for securing biopsy samples:

  • Needle
  • Camera-assisted
  • Surgical


Needle biopsies are the least invasive option and they work by drawing fluid from the affected tissue through a needle. In many cases, it’s difficult to procure a sufficient amount of fluid to make an accurate diagnosis. If that’s the case, your doctor will likely opt for a camera-assisted biopsy. This involves a minimally-invasive surgery in which doctors insert a tube with a camera attached to remove and later test sample tissue. Surgical biopsies are, of course, the most invasive and are generally used when the tumor is an inconvenient location for needle or camera-assisted biopsies.

Even with all these options, mesothelioma is routinely misdiagnosed. It can often present as a more common disease or even a condition that isn’t nearly as deadly. For instance, some doctors mistake the early signs of pleural mesothelioma for asthma or the flu. If you suspect that you or a loved one may have mesothelioma, it’s important to act quickly and let your doctor know.


Mesothelioma staging is an important method for identifying the spread of the disease in a patient’s body. Other cancers use a similar staging method. For mesothelioma, it is generally agreed that there are four stages with stage 1 having the best prognosis and stage 4 having the worst.

The staging system can be summarized as follows:

Stage 1

The tumor is localized and the mesothelioma has yet to metastasize or spread to other organs or tissues or the lymph nodes. Surgery and other curative treatments can be used and the prognosis is better than all other stages.

Stage 2

The mesothelioma has limited spread to nearby organs and possibly the lymph nodes, but to a small degree. The tumor is still localized and surgery may still be an option along with other curative treatments.

Stage 3

The mesothelioma has taken over one side or region of the body and has also infected the lymph nodes. Surgery is typically unavailable at this point, but other curative treatments may be administered. Palliative treatments are also often required at this stage.

Stage 4

The mesothelioma has invaded multiple regions of the body and has begun affecting several organs, tissues, blood vessels, and the lymph nodes. Surgery is, again, not an option, and most treatments at this stage are palliative. This stage has the worst prognosis.

This, of course, does not mean that all hope is lost when a patient is diagnosed with stage 4 mesothelioma, and it also doesn’t mean that a stage 1 diagnosis is any less worrisome. A patient with stage 4 mesothelioma can go into remission (though it is rare) and a patient’s stage 1 mesothelioma can begin spreading despite treatment.

It should be noted that the stage remains the same no matter what happens physically within the body. For instance, a patient diagnosed with stage 2 mesothelioma that ends up spreading to an entire region of the body will still be considered to have stage 2 mesothelioma that further metastasized.

Pleural mesothelioma is the only type of the disease that has a clinically accepted standard for staging. The TNM Staging System—which takes tumor, node, and metastasis into account—is approved for use by the American Joint Committee on Cancer and the International Mesothelioma Interest Group.

Other forms of mesothelioma follow this staging system or a general cancer staging system to some degree.


For many people, the symptoms are the primary aspect of any mesothelioma definition. The symptoms of mesothelioma are generally not specific to the disease, which is why it often gets misdiagnosed. The illness can also be asymptomatic for up to 50 years before it starts to show any signs.

Symptoms are different depending on the location of the tumor. For example, pleural mesothelioma symptoms are usually localized in the chest and lung area whereas peritoneal mesothelioma symptoms are localized in the abdomen.

Specific pleural mesothelioma symptoms include:

  • Shortness of breath
  • Constant coughing (possibly with the appearance of blood)
  • Hoarseness
  • Trouble with speaking or swallowing
  • Chest pain
  • Lower back discomfort
  • Fluid buildup around the lungs

Symptoms of peritoneal mesothelioma can often be mistaken for irritable bowel syndrome or a hernia.

They include:

  • Nausea
  • Vomiting
  • A range of abdominal pain
  • Fluid buildup that causes abdominal swelling
  • Weight loss
  • Appetite loss
  • Difficulty breathing
  • Fatigue and weakness
  • Bowel obstruction

Because of pericardial mesothelioma’s rarity, its symptoms typically go unnoticed. When they are identified, they are often confused for symptoms of another disease.

Common symptoms are:

  • Chest pain
  • Fluid buildup around the heart
  • Heart murmurs and other abnormal heart behaviors
  • High fever

These symptoms are usually the ones patients first start experiencing. In many cases, patients will ignore them or think they are an indication of a minor issue. Symptoms are very acute during the early stages of the disease when it would be most advantageous to catch it.

As the disease progresses, however, symptoms become harder and harder to ignore.

Mesothelioma is most commonly diagnosed in stage 3. At that point, the pain is more severe, breathing becomes more difficult, and extreme fatigue may set in. This is the point at which most patients end up seeing a doctor. In stage 4 mesothelioma, nerve issues start coming into play. These include Horner’s syndrome, a nerve condition affecting the eyes, and laryngeal nerve palsy, a condition that causes hoarseness after the voice box is effectively paralyzed.

It’s also important to remember that mesothelioma symptoms can mimic a wide range of diseases and conditions, some more benign than others.

So, if you are exhibiting some of these symptoms, it doesn’t necessarily mean that mesothelioma is present. Still, it’s important to see a doctor to identify the actual cause of the issue.


As we’ve already noted, the cause of mesothelioma is exposure to asbestos. In the early 20th century, asbestos was prevalent in many building materials because of its efficiency as a fire retardant. It could also be found in numerous industries, which is why workplace asbestos exposure is the most common reason for incurring mesothelioma later on in life.

Of course, we also know that the disease doesn’t start showing any signs for an average of 30 to 40 years. Additionally, many people who have been exposed to the substance will never show any ill effects. So, how exactly does asbestos cause mesothelioma?

In most cases, asbestos fibers are inhaled or ingested and become lodged in the lining of the lungs, abdomen, and/or heart. These fibers act as irritants that eventually cause inflammation that can lead to the creation of tumors.

Factors that affect the likelihood of incurring mesothelioma include:

  • Duration – how long an individual was regularly exposed to asbestos
  • Amount – the quantity of asbestos fibers inhaled or ingested
  • Type – there are six different types of asbestos with crocidolite being the most dangerous

Most asbestos exposure occurs on jobsites. Many occupations (particularly in the past) required prolonged exposure to substantial amounts of asbestos which greatly increased workers’ susceptibility to mesothelioma.

It Takes 20 to 50 years for Mesothelioma to Develop Following Exposure


Asbestos exposure is most common in the following jobs:

  • Construction workers
  • Shipyard workers
  • Firefighters
  • Industrial workers
  • Miners
  • Power plant workers
  • Oil refinery employees

That’s not to say that exposure can’t happen elsewhere. Building materials like insulation, paint, and electrical wiring that contain asbestos can still be found in schools, offices, homes, and other locations you wouldn’t necessarily expect.

Of course, most of that asbestos is static and won’t hurt you, but if the building in question is disturbed (e.g. for a demolition or renovation) then there may be a danger.

Secondhand exposure to asbestos can also occur in some instances. This usually happens when an individual is in close contact with someone who regularly works with asbestos or they live near a facility that produces substantial amounts of asbestos (such as an oil refinery).


The term “metastasis” isn’t something you’ll find only in a mesothelioma overview. It refers to the spread of any cancer from its original tumor to other regions of the body. Mesothelioma is considered a particularly aggressive form of cancer because it can spread rapidly once it starts to metastasize. Sadly, mesothelioma that exhibits metastasis is usually fatal within about a year.

Metastasis can occur via several different avenues within the body.

The cancer cells can move through the:

  • Bloodstream
  • Lymph nodes
  • Lymphatic system
  • Blood vessels that have been newly created

Stage 1 and stage 2 mesothelioma do not exhibit a large degree of metastasis, although, in those stages, the disease can spread to nearby tissues. Instead, aggressive and widespread metastasis generally occurs in stages 3 and 4 of the disease. This is usually when mesothelioma is diagnosed.

Cancerous mesothelioma cells can spread virtually anywhere in the body, but they most commonly attack the:

  • Liver
  • Lungs
  • Kidneys
  • Adrenal glands
  • Spleen
  • Pancreas
  • Appendix
  • Thyroid
  • Heart

Of course, the spread of the disease also largely depends on its initial location. For instance, pleural mesothelioma begins its spread in the chest cavity affecting organs like the lungs and heart whereas peritoneal mesothelioma starts to metastasize in the abdominal cavity affecting organs like the pancreas and appendix. Again, both forms of the disease can spread virtually anywhere.

Additionally, the mesothelioma cell type can also dictate the level to which the disease metastasizes. Sarcomatoid cells, found more commonly in peritoneal mesothelioma, are the most aggressive and will spur a faster spread. Epithelioid cells, found most commonly in pleural mesothelioma, are slower to develop but not any less deadly.

Risk Factors

As mentioned above, the main risk factor for developing mesothelioma is exposure to asbestos. In fact, it is the only known cause of the disease. Individuals who worked with large amounts of asbestos for long durations of time are at the highest risk. But, again, asbestos can also be found in locations outside of the workplace.

Facts and Statistics

Doctors and researchers are understanding mesothelioma more and more every day. Even so, it is still a very deadly disease.

Two to three thousand people are diagnosed with the illness each year in the United States alone.

An average of 2,500 individuals succumbs to the disease annually in the country.

From 1999 to 2015, there were over 45,000 known total deaths caused by mesothelioma in the U.S.

Throughout the world, around 43,000 people die each year due to mesothelioma.

Asbestos, the agent that causes mesothelioma, is banned (either completely or partially) in 61 nations throughout the globe. Unfortunately, the United States remains one of the only developed nations to not enact a complete ban on the substance. Although it has been illegal to mine for asbestos in the U.S. since 2002, it is still legal to import products containing the mineral. The country imported 680,000 pounds of asbestos in 2016.

Because of advancements in technology, survival rates for sufferers of peritoneal mesothelioma have greatly improved.

The 10-year survival rate for that type of the disease is 39%.

The 10-year survival rate for pleural mesothelioma, the most common type of the disease, is only 4.7%.

Overall, however, survival rates have remained static over the last few decades at 7 to 9% after five years. This can largely be attributed to the fact that pleural mesothelioma accounts for over 75% of mesothelioma cases and most individuals with the disease have a life expectancy of around a year.

Mesothelioma rates are highest in Belgium, the United Kingdom, and Australia. Of course, this metric may be flawed as many other nations don’t keep accurate tallies of the incidence of mesothelioma. The incidence of mesothelioma in developed countries is predicted to increase by between 5 and 10% by the year 2020.

Despite these bleak numbers, there is still hope on the horizon. Patients who are treated with a combination of surgery, chemotherapy, and radiation therapy have far improved prognoses than those who opt only for one or two of those treatments.

Additionally, 50% of all mesothelioma patients will enroll in clinical trials, allowing them to obtain the most updated treatments.

In the end, there is nothing particularly positive about a mesothelioma diagnosis.

Anyone who has had to ask “what is mesothelioma?” probably knows about its dangers. Still, new treatment options are extending life expectancy with the ultimate goal of finding a cure at some point.