Mesothelioma is a rare form of cancer that arises from mesothelium, which consists of the pleura of the lungs, the pericardium around the heart and the peritoneum in the abdomen. The pleura is made up of two thin layers of membrane that surround the entire surface of the lung including the areas between the lobes. Cancer that starts in the pleura can spread to other parts of the body. When the cancer starts from the lung pleura, it is called malignant pleural mesothelioma (MPM).
There are three histologic subtypes of mesothelioma:
Epithelioid accounts for 60% to 70% of all cases and usually has the best prognosis.
Sarcomatoid accounts for 10% to 15% of all cases. It is a much more aggressive form of mesothelioma.
Biphasic or Mixed accounts for 10% to 15% of cases. This form has characteristics of both epithelioid and sarcomatoid mesotheliomas but is associated with worse survival than epithelioid mesothelioma.
In patients with MPM, fluid builds up in the space between the two layers of membrane, puts pressure on the lung and may cause the lung to collapse. Symptoms include:
Having one or more of the symptoms listed above does not necessarily mean you have mesothelioma. However, it is important to discuss any symptoms with your doctor, since they may indicate other health problems.
The majority of cases of mesothelioma are due to asbestos exposure. Asbestos is a fibrous mineral that has many subtypes. Unfortunately, asbestos was used extensively in the past in the construction, automotive, military, marine and manufacturing industries. When the tiny particles of asbestos are being manufactured, they can float in the air and be inhaled or swallowed. This can subsequently lead to serious health conditions such as cancers of the lung, larynx and kidney, as well as causing asbestosis (a non-cancerous, chronic lung ailment). In people who are susceptible, the asbestos fibers cause genetic changes in the lung pleura which may ultimately lead to the development of mesothelioma. MPM can occur 20 to 50 years after the primary asbestos exposure.
There are currently no methods to prevent mesothelioma if you have been exposed to asbestos in the past.
There are no standardized screening tests that have been shown to improve mesothelioma outcomes. However, a blood test measuring osteopontin (a protein which is a component of bone) is currently being evaluated to determine if it can predict the development of mesothelioma in patients exposed to asbestos.
Because the symptoms of mesothelioma are non-specific, the disease can be difficult to diagnose. In particular, pleural effusion (fluid accumulation in the chest cavity) can occur in many other conditions such as lung cancer, heart failure and pneumonia.
An evaluation for mesothelioma may include:
It is not unusual for doctors to be uncertain about the diagnosis, even after biopsy and removal of chest fluid. If your disease has been diagnosed at another medical facility, you should have all of your biopsy specimens reviewed by a pathologist experienced in the diagnosis of mesothelioma.
The word “staging” describes the extent of the cancer. When the stage of your cancer is known, your doctor can choose the most appropriate treatment.
Stage 1A: Tumor involves the outermost layer of pleura (parietal pleura), but does not involve the pleura covering the lung (visceral pleura).
Stage 1B: Tumor involves the parietal as well as the visceral pleura.
Stage 2: Tumor invades into the lung or diaphragm (the thin muscle that separates the chest from the abdomen).
Stage 3: Tumor invades into the fibrous sac around the heart (pericardium), into the chest wall (in one area only) or involves the lymph glands within the chest.
Stage 4: Tumor involves multiple areas of the chest wall, extends across the diaphragm or through the pericardium, involves other organs such as the heart, windpipe or esophagus, or has spread to other organs such as the liver or opposite lung.
The treatment for MPM may require surgery, chemotherapy and radiation. Depending on your stage of disease and where the cancer is located, you may receive one or more of these treatment modalities. Previously, many doctors and specialists were hesitant to recommend aggressive treatment because MPM was very resistant. However, there have been several advancements in mesothelioma therapy that have improved survival outcomes in the last few years. In some patients, aggressive therapy including surgery, radiation therapy and/or chemotherapy may result in long-term survival and perhaps cure.
The choice of treatment depends on many factors, including the location and stage of the cancer as well as the age and general health of the patient. The majority of mesothelioma patients who have been cancer-free for a long time have had surgery as part of their treatment. In patients where surgery is not an option, recent developments in new agents that target crucial pathways that regulate MPM cells have offered new hope for improving outcomes.
The two main goals of MPM surgery are to:
Two main forms of surgery are available:
Pleurectomy or Pleurectomy/Decortication (P/D) involves peeling the tumor away from the lung, diaphragm and chest wall but leaving these structures intact. In most instances, the tumor cannot be entirely removed. In these cases, it is not possible to give high doses of radiation to the chest because the lung and diaphragm remain intact. Leaving in the structures limits the total dose of radiation that can be delivered after surgery. Local recurrences are significantly higher than with extrapleural pneumonectomy, however, because the lung tissue is preserved and the patient’s lung function is usually well-maintained. MD Anderson may perform a pleurectomy or pleurectomy/decortication on patients who cannot tolerate extrapleural pneumonectomy because of poor lung or heart function.
Extrapleural pneumonectomy (EPP) is considered at MD Anderson to provide the best chance of complete tumor removal and allows for other therapies to be given with less risk to the remaining vital organs. EPP is an extensive surgical procedure that involves removal of all organs involved, including the lung, lymph glands and portions of the diaphragm and the pericardium (sac that surrounds the heart). The diaphragm and pericardium are reconstructed with a sheet of artificial material. Patients must be in good physical shape to tolerate the procedure.
Radiation therapy alone is not a successful curative treatment for mesothelioma. However, when administered after surgery, it can reduce the chances of tumor coming back. Also, in some cases, radiation may be administered as prophylaxis to an incision site to prevent tumor recurrence or to a specific site to palliate pain or symptoms of discomfort. The most common use of radiotherapy though, is after surgery to prevent disease recurrence.
There are several ways of delivering radiotherapy. MD Anderson pioneered the use of intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy. IMRT is an advance in radiotherapy that involves giving highly accurate three-dimensional radiation after the lung and pleura have been removed. This technology may lead to improved outcomes and less toxicity to the patients over hemi-thoracic external beam radiotherapy.
IMRT for mesothelioma was developed at MD Anderson, and currently very few institutions offer it. It requires careful planning of the radiation treatment area and close collaboration between the surgeon and radiation oncologist. Areas thought to be at high risk for tumor recurrence are carefully mapped out on CT scans and analyzed by a computer, which performs three-dimensional dosage calculations. Using this technique, high doses of radiation can be very accurately administered to the entire chest cavity.
In MPM patients who receive surgery, MD Anderson may recommend giving chemotherapy as well as part of multi-modality treatment. However, it is highly recommended that patients consider enrollment onto a clinical trial which will provide surgery, radiotherapy, chemotherapy and a biologic targeted agent. Your physicians will recommend a clinical trial if it is appropriate.
In patients who are not surgical candidates, the usual treatment is chemotherapy or a clinical study with a new targeted agent to treat the cancer. Since chemotherapy does not cure mesothelioma, we highly recommend treatment on clinical trials which may use chemotherapy in combination with a new targeted biologic therapy or a biologic agent alone. The current standard practice in the United States (when not on a clinical trial) is to receive treatment with chemotherapy agents cisplatin or carboplatin and pemetrexed (Alimta®). Other chemotherapy drugs that are commonly used include gemcitabine and vinorelbine. However, the future of systemic therapy for mesothelioma will be focused on targeted agents and personalized medicine. Personalized medicine means that the choice of treatment will be based on the individual cancer’s specific genetic/molecular profile.
Cancer is a journey that no one needs to take alone. There are many forms of support to help you through every stage: diagnosis, treatment and survivorship. Whether you meet with other cancer survivors like yourself, use complementary therapies or individual coping mechanisms, support is available. Listed below are just some of the ways to find help...and hope.
Getting together with other cancer patients in a support group is a valuable coping tool. Support groups are usually focused on a single disease or topic, such as breast cancer survivors or people coping with life-changing side effects from their cancer or cancer therapy. These groups allow participants to meet others like themselves and seek strength from each other. Most major cities and cancer hospitals offer support groups that meet weekly or monthly. There are also dozens of online support web sites or message boards for those who may not have access to a traditional meeting.
Complementary therapies are used in conjunction with cancer treatment, in an effort to reduce treatment side effects, ease depression and anxiety and help cancer patients take their mind off the negative aspects of their situation. Complementary therapies may include mind-body exercises like yoga, tai chi and Qi gong; visualization or guided imagery; using art or music as therapy and self-expression and traditional Eastern medicine such as acupuncture.
Staying physically active as much as possible during cancer treatment has many positive benefits. Physical activity stimulates the release of endorphins, a hormone that helps elevate mood, as well as decreasing feelings of fatigue.
Exercises for cancer patients can range from simple stretches done in the bed or chair, to more active pursuits such as walking or light gardening work. However, it’s important not to push yourself too hard. Check with your doctor before attempting any physical activity to make sure you are up to it.
Many people find it helpful to keep a journal of their cancer treatment experience. It may be as simple as recording symptoms and side effects into a notebook, or may include personal emotions and opinions about what they may be going through. Journals can be private, like a diary, or shared with loved ones and even strangers.
Increasingly, people are turning to the Internet to share their cancer journey with the world at large and to seek out others with similar experiences. Many cancer patients have begun their own web log, or “blog” to publicize their battle with cancer. Twitter, a mini-blogging technology that limits posts to 140 characters, has also proven to be a helpful tool for cancer patients to keep friends updated and reach out to others.