Mesothelioma

Malignant mesothelioma is a rare and aggressive cancer which is almost always caused by asbestos exposure. This devastating disease attacks the mesothelium, the protective membrane that covers the lungs, abdomen, and heart.

Although you may never have heard of the mesothelium, you could not function without it. This thin layer of protective tissue lubricates and protects the internal organs, and allows them to move easily inside the chest and abdomen. Without the mesothelium, your lungs, heart, and stomach could not expand and contract freely.

When a person has mesothelioma, their mesothelial cells become malignant and grow out of control. As the tumor expands, it produces a fluid called a pleural effusion, which builds up in the chest or abdomen and presses on the surrounding organs. Eventually, the cancer cells may metastasize into the chest wall, lymph nodes, lungs, liver, or even the brain.

An estimated 2000 to 3000 people in the United States are diagnosed with mesothelioma each year. Tragically, there is still no known cure. However, the number of treatment options is steadily increasing. If the cancer is caught early enough and treated effectively, a patient’s prognosis can be significantly improved. Cancer researchers are also working to develop innovative new therapies that may dramatically improve outcomes for mesothelioma patients in the future.

Types

Mesothelioma is divided into different types depending on where it occurs in the body. Each type has different symptoms and different treatment options. About 75% of cases are pleural mesothelioma, which develops in the pleural lining of the lungs. Another 10 to 20% of cases are peritoneal mesothelioma, which occurs in the lining of the abdominal cavity, or peritoneum. Very rarely, mesothelioma may also develop in the pericardial lining of the heart, or the tunica vaginalis surrounding the testicles.

Mesothelioma can also be classified by the type of cancer cell.  The cell type may be epithelial, sarcomatoid, or a mix of the two (known as biphasic).  The majority of mesotheliomas are epithelial, and the epithelial type is somewhat easier to treat.

It is also important to note that there are some benign tumors of the  mesothelium.  These tumors are typically removed by surgery with no further treatment.

Causes

Malignant mesothelioma is almost always caused by asbestos exposure. The majority of people who are diagnosed with mesothelioma have a history of occupational exposure. However, even very brief or low levels of asbestos exposure can cause mesothelioma, including household exposure, bystander exposure, and even environmental exposure.

In some cases, it may be difficult to identify the exact source of the asbestos exposure due to mesothelioma’s long latency period.  Latency refers to the length of time between the first exposure to asbestos and the onset of the disease itself.  Mesothelioma typically has a latency period of 10 to 40 years.

Symptoms

The symptoms of mesothelioma may vary depending on whether it is pleural, peritoneal, or pericardial. Generally, symptoms may include:

• Pain in the chest or abdomen
• Shortness of breath
• Persistent cough or changes in the way you cough
• Weight loss
• Difficulty swallowing
• Prolonged hoarseness
• Abdominal swelling
• Obstructed bowels
• Inability to sleep
• Fever and/or night sweats
• Blood in the sputum.

Diagnosis

Mesothelioma can be difficult to diagnose.  The symptoms of mesothelioma are often similar to the symptoms of other diseases.   Also, since mesothelioma is relatively rare, many doctors have very limited experience with the disease.  Therefore, if you have a history of asbestos exposure, it is very important to have regular physical examinations to monitor the functioning of your lungs and abdomen.  You should also visit the doctor as soon as you begin to show any of the symptoms of mesothelioma.

Stages

If a diagnosis of mesothelioma is confirmed, your doctor will probably order additional tests to determine the stage (or extent) of the disease.  This helps the doctor plan the proper course of treatment.

Treatment

Options for mesothelioma treatment are steadily increasing.  Standard treatments include surgery, radiation, and chemotherapy, which are often combined in what is known as a multi-modality approach.  Some patients may also want to explore complementary or alternative remedies.

All of the treatments that are currently available can help to relieve a patient’s symptoms and prolong their life.  Tragically, however, the existing therapies cannot cure mesothelioma.  The median life expectancy of a mesothelioma patient is less than two years, in part because many patients are not diagnosed until the disease has already advanced to a late stage.  However, you should not lose hope simply because the statistics are discouraging.  Remember that each patient is different.  Some people respond very well to the existing treatments, and may live many years after their mesothelioma diagnosis.  A patient’s prognosis depends on a variety of factors.

Most importantly, there is now more research on mesothelioma than ever before.   There are currently over 100 mesothelioma clinical trials underway to test new treatments.  If you qualify, a clinical trial may be the best treatment option available.  These clinical trials offer some of the most up-to-date therapies available, with the highest possible standard of care.   In addition, the research conducted in these trials will lead to improved treatment for all mesothelioma patients and may someday lead to a cure.

It is important to learn as much as you can about the newest treatments and latest clinical trials.  With a little research, you can be your own advocate and help your medical team develop a treatment plan that makes sense for you or your loved one.  You can look at our clinical trials section for a list of trials that are currently recruiting patients.  We also urge you to discuss clinical trials with your doctor.

Sources

National Cancer Institute, “Mesothelioma: Questions and Answers”

“Malignant Mesothelioma: Advances in Pathogenesis, Diagnosis, and Translational Therapies,” by Harvey Pass, Nicholas Vogelzang, Michele Carbone, (Springer: 2005).