Mesothelioma

What is Mesothelioma

Tumors of the mesothelium can either be benign (non-cancerous) or malignant (cancerous). Malignant mesothelioma, often called mesothelioma, is much more common than benign mesothelioma. A malignant tumor is very dangerous because it has the ability to spread to other parts of the body.

Malignant mesothelioma has three different types: epithelioid, sarcomatoid, and mixed/biphasic. Around 50 to 70 percent of mesothelioma cases are epithelioid, which also has the best diagnosis. The sarcomatoid type is 7 to 20 percent, and the mixed/biphasic type is 20 to 35 percent. The epithelioid type affects the membranous tissue covering internal organs and other internal surfaces of the body. Sarcomatoid occurs from supportive tissue, such as bone, muscles, cartilage, or fat. Biphasic has features of both epithelioid and sarcomatoid. Treatment options vary each type.

Around three-fourths of mesothelioma cases start in the chest cavity, known as pleural mesothelioma. While 10 to 20 percent begin in the abdomen, called as peritoneal mesothelioma. Pericardial mesothelioma, or those starting in the cavity around the heart, are very rare. The covering layer of the testicles is in fact an outpouching of peritoneum into the scrotum. Mesothelioma affecting this covering of the testicles is fairly rare.

Mesothelioma is still quite uncommon. In the United States, there are about 2,000 to 3,000 new cases per year. People who are diagnosed with malignant mesothelioma are mostly over 50 years old and more often seen with people in their seventies, because they were exposed to asbestos in the 1940s to 50s or eearlier. People who were exposed to asbestos in the 1960s to 70s may be diagnosed in years to come. The disease affects men 3 to 5 times more than women; because men held more construction positions than women in earlier decades. Also, mesothelioma is more common to Caucasians than in African Americans.

Although this disease is uncommon, it is very dangerous. It is often in its advanced stages by the time it is diagnosed, making the results not as good as it is for other cancers that are found earlier. About 1 to 2 years is the average survival time after being diagnosed. But due to current medical technology and new treatments that are being developed for mesothelioma, survival rates are increasing.

Peritoneal Mesothelioma

The peritoneum, a thin membrane of mesothelial cells, surrounds many of the organs in the abdomen. On this membrane, is a tumor called peritoneal mesothelioma. The only known cause is exposure to asbestos; and since it can be inactive for many years it is not obvious until the tumor has begun to grow. Of all the mesothelioma cases, there is about one-fifth of peritoneal mesothelioma.

Peritoneal mesothelioma like any cancer can be either benign or malignant. Mesothelioma is often diagnosed by chance, before any symptoms come out. For instance, during a routine abdominal x-ray for a check-up or before surgery, a tumor is discovered.

The most common symptoms of peritoneal mesothelioma include weakness, weight loss, loss of appetite, abdominal pains, nausea, and abdominal swelling. Fluids often build up in the peritoneal space, known as ascites. The symptoms can become more severe over time.

The growing tumor can exert more pressure on the organs in the abdomen, leading to bowel difficulty and distention. The tumor can limit breathing if it presses upward. If the tumor pushes against areas where there are many nerve fibers, and the bowel distends, it will increase the amount of pain.

X-rays and CT scans are commonly the first step towards detecting peritoneal mesothelioma. The diagnosis is achieved by obtaining a piece of tissue. Peritoneoscopy is the procedure of looking at the peritoneum and it requires anesthesia. If an abnormality is apparent, the doctor will try to obtain a tissue sample (called biopsy). A pathologist will make a diagnosis from a microscopic analysis of specialized stains.

There are two explanations for how asbestos fibers can get into the peritoneum.
First, the fibers caught by the mucus of the bronchi and trachea are swallowed. Some fibers stay in the intestinal tract and from there they can move through the intestinal wall into the peritoneum. Second explanation is the fibers that stay in the lungs can move into the lymphatic system and be transported to the peritoneum.

Medical science does not know precisely how or why a carcinogen causes a cell to become cancerous. It is not certain whether only one fiber can cause a tumor to build up or whether it takes many fibers, or what the specific conditions are for this change to arise.

Currently, there are treatments but no known cure, for peritoneal mesothelioma. The diagnosis depends on many factors, including the cell type, the size and stage of the tumor, its degree, and whether or not the tumor reacts to treatment.

However, the choices for treatment and relief of people with peritoneal mesothelioma have improved, especially for those who diagnosed early and treated actively. A lot of people receive a combination of therapies, or multimodal therapy. Common types of treatment include radiation therapy, surgery, and chemotherapy and other drug-based therapies. There are also clinical trials and various new treatments like immunotherapy and gene therapy, and antiangiogenesis drugs.

What are Clinical Trials?

Clinical trials are research studies of different treatment medications and methods used to treat a disease to determine whether a new drug or treatment is safe and effective. A clinical trial is usually conducted after extensive research has been performed regarding a medication or treatment.

Before you decide to participate in a clinical trial, it is vital that you learn all of the potential risks and benefits. Discuss with your doctor if the trial you are interested in is right for you. Not every patient should or can participate in a clinical trial. Learn as much information as possible before making a decision about participating in a clinical trial.

Phases in a Clinical Trial

Usually, clinical trials are separated into three phases: Phase I, Phase II and Phase III.

Phase I trials involve a few patients. Generally, the goal of the trial is to find out the best way to administer a new treatment or medication, and in what dosage.

Phase II trials include a larger number of people. The goal is to assess the effectiveness of a specific treatment. The important part of these trials is the determination of whether the treatment is safe, and what side affects, if any, might arise.

Phase III trials keep up the research of phase II trials, but with a stronger focus on comparing this specific treatment with already existing treatments. Many participants are involved, divided into two or more groups, with each group being given another treatment. In this way, physicians can find out if a new treatment shows any promising advantages over existing treatments.

Potential Benefits and Risks of Clinical Trials

Benefits

Before participating in a clinical trial, one should first learn as much as possible about it. Discuss possible benefits and risks with your doctor.

Some of the potential benefits are:

• Health care given by leading physicians in cancer research

• Access to new drugs before they become available to market

• The new treatment may be more effective than the standard treatment

• Some of your treatment may be without charge

• Having proactive role in your treatment

• The opportunity to make a contribution to cancer research

Potential Risks

While some potential risks may include:

• New drugs may have unfamiliar side effects

• New drugs may be ineffective other than the treatments currently available

• A treatment that is effective on one person, may not work on the other since individuals respond differently to treatment.

Mesothelioma Treatment: Radiation

Radiation therapy involves the use of high-dose radiation on malignant tumors. Radiation therapy includes radiotherapy, implant radiation, brachytherapy, or interstitial radiation therapy. To remove cancer cells and shrink tumors, physicians use high-energy x-rays, neutrons, photons, cobalt or other radiation sources. The radiation may come from materials (radioisotopes) or from a machine (external-beam radiation therapy) that create radiation. These materials are preserved into thin plastic wires, tubes, needles, or catheters and placed near to or into the tumor (internal radiation therapy).

The radiation damage the cancer cells so they can no longer continue to multiply. This will result in size reduction of the affected tumor. The entire tumor and malignancy that has spread to nearby tissues however is very resistant to treatment. Thus, radiology is usually not used in isolation but is as one of several other therapies, like chemotherapy and surgery.

Radiation is efficient because mesothelioma is made up of rapid growing cells and radiation is most effective on cells that divide quickly. There will be a series of treatments in the course of treatment. With each treatment more cells die or injured and therefore the tumor gets smaller. Radiation therapy is an effective palliative (symptom relief) treatment. Relief of symptoms is achieved, such as pain and shortness of breath. But not all the diseased cells can be removed without severe effects on the patient’s body. The remaining cells will keep on dividing and multiplying.

Radiation therapy affects only the area that is being treated, but not selective in its affects. Healthy cells and the tumor cells in the treated area may be affected by this treatment. Most of the damaged healthy cells start to repair themselves hours after exposure and can get better from this treatment. However, the damage to the healthy cells is the cause for the side effects of radiation therapy. The side effects that happen during radiation therapy are manageable and should be talked openly with the doctors and nurses providing care.

The size, location, type, and grade of tumor resolve which, how much and how often radiation will be given. Complex calculations are used to know the dosage and timing of radiation in treatment planning. Normally, the treatment is given from a few different angles to be able deliver the maximum amount of radiation to the tumor and the minimum amount to normal tissues. The radiation used in the treatments does not stay in the body. It is eliminated from the body during the natural cleansing action of the blood and is excreted from the body, together with dead tumor cells. Radiation therapy can be limited as an option of treatment by the size of the tumor and its closeness to vital organs.

Mesothelioma Treatment: Surgery

Surgery is the operation or procedure, especially one involving the removal or replacement of a diseased organ or tissue.

Pleural Surgery

Tumors of the pleural mesothelium are usually diagnosed in one lung or in one lung being more significantly involved than the other lung. These tumors have typically extended into surrounding tissues and the lung itself. Therefore, taking away the affected lung and nearby tissues is an option for treatment.

Below are several types of surgery in treating pleural mesothelioma:

• A pleurectomy/decortication eliminates part of the lining of the chest and some of the tissues around it. This procedure can decrease the size of the tumor. Using a palliative treatment, it decreases chest pains and helps to avoid fluid from forming in the affected area. With the use of this procedure, statistics show slight increase in the survival rate.

• A pneumonectomy takes away a lung, the lining that surrounds the lung, and some tissues around it. This type of surgery is comparable to pleurectomy with the additional removal of the lung.

• An extrapleural pneumonectomy is an option when the tumor is localized and diagnosed early. The patient must be generally in good health and with no severe illnesses. The purpose of extrapleural pneumonectomy is to take away all of the affected tissue. It eliminates the parietal pleura (the lining of the lung), the pericardium (the lining of the heart), the diaphragm (the muscle that assists in breathing) and the affected side of the lung. This is a major surgery that is performed only by surgeons. The system of chemotherapy and radiology follows the surgery. Recovery time for the whole treatment is about one year. Patients who experience this treatment have a survival rate of about 3 1/2 years and often are able to lead a quite normal life.

• Thoracentesis is a surgical type as a diagnostic or a palliative treatment. Fluid in the pleural methothelium is eliminated by inserting a syringe into the mesothelium and withdrawing fluid. This reduces pressure, pain and improves the ability to breathe.

Peritoneal Surgery

Peritoneal mesothelium surgery is performed to take away malignant tissues and the affected abdominal organ when necessary. Peritoneal surgery is also primarily used as a palliative procedure.

Pericardial Surgery

The unusual form of mesothelioma affects the lining of the heart. Surgery for this case takes away the lining around the heart. This is a palliative treatment commonly not intended to achieve a cure.

Orchidectomy (also called orchiectomy)

The very rare form of mesothelioma affects the testicles and is categorized as a peritoneal (abdominal) mesothelioma. Surgical treatment is similar for other organs of the abdomen, which includes elimination of the affected mesothelium and sometimes the affected organ (orchidectomy).