mesothelioma---Diagnosis---etc

Diagnosis

A doctor should be seen if a person experiences shortness of breath, chest pain, or pain or swelling in the abdomen. If these symptoms are present, the doctor may order an x ray of the abdomen or chest. The doctor will do a complete physical examination and take a thorough medical history. Then, one or more of the following methods may be used to ascertain whether mesothelioma is present.

• Imaging tests. These tests may include x rays, computed tomography (CT scans), or magnetic resonance imaging (MRI) to allow the doctor to visualize the area in question. These studies will help determine the location, size, and extent of the cancer.
• Pleural biopsy. Diagnosing mesothelioma requires an adequate biopsy specimen. However, because mesothelioma usually arises from the lower part of the diaphragmatic and/or parietal pleura, obtaining enough tissue may be difficult. A simple, or closed, pleural biopsy involves the insertion of a needle into the chest cavity to obtain tissue from the pleural membrane for analysis. This technique is minimally invasive and normally requires only local anesthesia. This technique, however, may not provide adequate material for the necessary stains of the tissue to make a diagnosis of mesothelioma. Moreover, since the biopsy is not done under direct vision, the sample may not be exactly in the area of the tumor. If the diagnosis cannot be made with this relatively noninvasive technique, an adequate tissue sample usually can be obtained via an open pleural biopsy. In this approach, a surgeon makes an incision on the patient's side and goes into the pleural space. This method allows maximum exploration of the pleural membranes as well. However, the technique requires general anesthesia.
• Thoracoscopy. A thoracoscopy, which is a relatively new technique, allows the doctor to look directly into the chest (pleural) cavity at the tumor and during the same operation to also take a tissue sample for laboratory analysis. The thoracoscopy is performed by making a small incision into the chest and using a tiny video camera to inspect the region. The doctor can then use forceps to obtain a tissue biopsy. A laparoscopy, a similar operation, is used to obtain a biopsy of a peritoneal tumor.
• Bronchoscopy. A bronchoscopy, which examines the airways, or a mediastinoscopy, which looks at the lymph nodes in the chest, allows the doctor to look at the area using a lighted tube. Samples may be taken with a needle and sent to the lab to find out if cancer cells are present. However, bronchoscopy and mediastinoscopy are not that effective for diagnosing mesothelioma, as the disease is seldom found within the airways or the lymph nodes.
• Surgery. This lets the doctor obtain a larger tumor sample or, on occasion, the entire tumor.

Diagnosing mesothelioma is often difficult, even with tissue biopsies. Microscopically, mesothelioma is often difficult to distinguish from several other forms of cancer. For this reason, certain laboratory tests are performed to help correctly diagnose mesothelioma. Some of these tests involve using antibodies to distinguish lung cancer from mesothelioma. Sometimes the tissue samples must be viewed under an electron microscope in order to get the correct diagnosis.

Treatment Team

A person with symptoms of mesothelioma will most likely seek help from a primary physician initially. During the diagnostic phase, various technicians will perform the imaging studies. A specially trained physician—a thoracic surgeon or, rarely, a pulmonologist—performs other diagnostic tests like pleural biopsy and thoracoscopy. A pathologist will view the tissue samples and make the tissue diagnosis. Following diagnosis, the patient will be offered some form of treatment, which may entail surgery, radiation therapy, chemotherapy, or a combination of these. The patient may receive care from a thoracic surgeon, an anesthesiologist, medical and radiation oncologists, and specially trained nurses who administer chemotherapy.

Clinical Staging, Treatments, and Prognosis

The treatment and outlook for those with mesothelioma depends a great deal on the stage of their cancer. Because the most frequently occurring type of mesothelioma is pleural, and it is also the one most studied, it is the only type for which a staging system exists. The following stages are based on a system known as the Butchart system, which divides mesothelioma into four stages:

• Stage I: Mesothelioma is found within the right or the left pleura and may also involve the lung, the pericardium, or the diaphragm on the same side.
• Stage II: In this stage, mesothelioma has spread to the chest wall or involves the esophagus, the heart, or the pleura on both sides. The lymph nodes in the chest may be involved as well.
• Stage III: Mesothelioma has gone through the diaphragm and into the lining of the abdominal cavity. Additional lymph nodes besides those in the chest may be involved.
• Stage IV: There is evidence that mesothelioma has spread through the bloodstream to distant organs or tissues.

Another system of staging mesothelioma is based on a TNM system (T=tumor, N=spread to lymph nodes, and M=metastasis). There are minor differences between this and the Butchart system. It is more detailed and precise, but the original Butchart system is still the one most often used to describe pleural mesotheliomas.

There are treatments available for all patients with malignant mesothelioma. The three kinds of treatment used are surgery, radiation therapy, and chemotherapy.

Surgery is a common treatment for mesothelioma. It is not an option unless the cancer is limited to one place and unless the person can withstand the surgery. During surgery, the physician may remove a portion of the lining of the chest (pleurectomy) or abdomen (peritonectomy) and some of the tissue surrounding it. Depending on the extent the disease has spread, a lung may also require removal (extrapleural pneumonectomy). Occasionally, a portion of the diaphragm is taken out as well. If treatment is not possible, other less invasive measures can be used to relieve the patient's symptoms. For example, a needle placed into the chest cavity (thoracentesis) can remove excess fluid in the chest. If recurrence of fluid causes symptoms, a nonsurgical or surgical method can be used to scar the lining of lung cavity and cause it to adhere to the lung. The procedure obliterates the pleural space and thus prevents the fluid from reaccumulating. (This procedure is called sclerosis or sclerotherapy.) These methods are called palliative, for they are not meant to cure the cancer but to improve symptoms.

Radiation therapy uses high-energy x rays to kill cancer cells and cause tumor shrinkage. It is rarely used as the primary treatment for pleural mesothelioma in those patients for whom surgery is not an option. It may also be used as an adjunct to surgery or as a method of alleviating various symptoms like trouble with swallowing, pain, and shortness of breath.

Chemotherapy involves the use of drugs to kill cancer cells. The most commonly used drugs are doxorubicin, cisplatin, and methotrexate. The medicines are delivered into a vein or taken by mouth. In the treatment of mesothelioma, they may also be injected directly into the chest or abdominal cavity. Chemotherapy may be given as the main treatment or may be an addition to surgery, depending on the type and stage of the cancer.

A new treatment being studied for early stages of mesothelioma confined to the chest is called intraoperative photodynamic therapy. This treatment uses special drugs that make cancer cells more sensitive to killing by a laser light. The drugs are given several days before surgery. During surgery, the special light is used to shine on the pleura.

By the time symptoms show up and mesothelioma is diagnosed, the disease is often advanced. The average survival period after diagnosis is about one year. If the cancer is found before it has spread and it is treated aggressively, about half of the patients will live two years, and approximately 20% will survive five years.