Mesothelioma:Mesothelioma What is the mesothelium?The mesothelium has different names, depending on itslocation in the body. The peritoneum is the mesothelialtissue that covers most of the organs in the abdominalcavity. The pleura is the membrane that surrounds thelungs and lines the wall of the chest cavity.The pericardium covers and protects the heart. Themesothelial tissue surrounding the male internalreproductive organs is called the tunica vaginalis testis.The tunica serosa uteri coversthe internal reproductive organs in women. What is mesothelioma?Mesothelioma (cancer of the mesothelium) is a diseaseinwhich cells of the mesothelium become abnormaland divide without control or order. They can invadeand damage nearby tissues and organs. Cancer cellscan also metastasize (spread) from their original site toother parts of the body. Most cases of mesotheliomabegin in the pleura or peritoneum. How common is mesothelioma?Although reported incidence rates have increased inthe past 20 years, mesothelioma is still a relativelyrare cancer. About 2,000 new cases of mesotheliomaare diagnosed in the United States each year.Mesothelioma occurs more often in men than in womenand risk increases with age,but this disease can appearin either men or women at any age. What are the risk factors for mesothelioma?Working with asbestos is the major risk factor formesothelioma. A history of asbestos exposure at workis reported in about 70 percent to 80 percent of allcases. However, mesothelioma has been reported insome individuals without any known exposureto asbestos. Asbestos is the name of a group of minerals that occurnaturally as masses of strong, flexible fibers that canbe separated into thin threads and woven. Asbestos hasbeen widely used in many industrial products, includingcement, brake linings, roof shingles, flooring products,textiles, and insulation. If tinyasbestos particles float in the air, especially during themanufacturing process, they may be inhaled or swallowed,and can cause serious health problems. In addition tomesothelioma, exposure to asbestos increases the risk oflung cancer, asbestosis (a noncancerous, chronic lungailment), and other cancers, such as those of the larynxand kidney. Smoking does not appear to increase the risk ofmesothelioma. However, the combination of smoking andasbestos exposure significantly increases a person's riskof developing cancer of the air passageways in the lung.Who is at increased risk for developing mesothelioma?Asbestos has been mined and used commercially since thelate 1800s. Its use greatly increased during World War II.Since the early 1940s, millions of American workers havebeen exposed to asbestos dust. Initially, the risksassociated with asbestosexposure were not known. However, an increased risk ofdeveloping mesothelioma was later found among shipyardworkers, people who work in asbestos mines and mills,producers of asbestos products, workers in the heatingand construction industries, and other tradespeople.Today, the U.S. Occupational Safety and HealthAdministration.(OSHA) sets limits for acceptable levelsof asbestos exposure in the workplace. People who workwith asbestos wear personal protective equipment tolower their risk of exposure. The risk of asbestos-related disease increases with heavierexposure to asbestos and longer exposure time. However,some individuals with only brief exposures havedeveloped mesothelioma. On the other hand,not all workers who are heavily exposed developasbestos-related diseases. There is some evidence that family members and othersliving with asbestos workers have an increased risk ofdeveloping mesothelioma, and possibly other asbestos-related diseases. This risk may be the result of exposureto asbestos dust brought home on the clothing and hairof asbestos workers. To reduce the chance of exposingfamily members to asbestos fibers, asbestos workers areusually required to shower and change their clothingbefore leaving the workplace. What are the symptoms of mesothelioma?Symptoms of mesothelioma may not appear until 30 to50 years after exposure to asbestos. Shortness of breathand pain in the chest due to an accumulation of fluid inthe pleura are often symptoms of pleural mesothelioma.Symptoms of peritoneal mesothelioma include weightloss and abdominal pain and swelling due to a buildup offluid in the abdomen. Other symptoms of peritonealmesothelioma may include bowel obstruction, bloodclotting abnormalities, anemia, and fever. If the cancerhas spread beyond the mesothelium to other parts ofthe body, symptoms may include pain, trouble swallowing, or swelling of the neck or face. These symptoms may be caused by mesothelioma or byother, less serious conditions. It is important to see a doctorabout any of these symptoms. Only a doctor can make adiagnosis. How is mesothelioma diagnosed?Diagnosing mesothelioma is often difficult, because thesymptoms are similar to those of a number of otherconditions. Diagnosis begins with a review of the patient'smedical history, including any history of asbestos exposure.A complete physical examination may be performed,including x-rays of the chest or abdomen and lung functiontests. A CT (or CAT) scan or an MRI may also be useful.A CT scan is a series of detailed pictures of areas insidethe body created by a computer linked to an x-raymachine. In an MRI, a powerful magnet linked to acomputer is used to make detailed pictures of areas insidethe body. These pictures are viewed on a monitor and canalso be printed. A biopsy is needed to confirm a diagnosis of mesothelioma.In a biopsy, a surgeon or a medical oncologist (a doctorwho specializes in diagnosing and treating cancer)removes a sample of tissue for examination under amicroscope by a pathologist. A biopsy may be done indifferent ways, depending on where the abnormal areais located. If the cancer is in the chest, the doctor mayperform a thoracoscopy. In this procedure, the doctormakes a small cut through the chest wall and puts a thin,lighted tube called a thoracoscope into the chest betweentwo ribs. Thoracoscopy allows the doctor to look inside thechest and obtain tissue samples. If the cancer is in theabdomen, the doctor may perform a peritoneoscopy. Toobtain tissue for examination, the doctor makes a smallopening in the abdomen and inserts a special instrumentcalled a peritoneoscope into the abdominal cavity. Ifthese procedures do not yield enough tissue, moreextensive diagnostic surgery may be necessary. If the diagnosis is mesothelioma, the doctor will want tolearn the stage (or extent) of the disease. Staging involvesmore tests in a careful attempt to find out whether thecancer has spread and, if so, to which parts of the body.Knowing the stage of the disease helps the doctor plantreatment. Mesothelioma is described as localized if the cancer isfound only on the membrane surface where itoriginated. It is classified as advanced if it has spreadbeyond the original membrane surface to other parts ofthe body, such as the lymph nodes, lungs, chest wall,or abdominal organs.How is mesothelioma treated?Treatment for mesothelioma depends on the location ofthe cancer, the stage of the disease, and the patient'sage and general health. Standard treatment optionsinclude surgery, radiation therapy, and chemotherapy.Sometimes, these treatments are combined. Surgery is a common treatment for mesothelioma.The doctor may remove part of the lining of the chestor abdomen and some of the tissue around it. Forcancer of the pleura (pleural mesothelioma), a lung maybe removed in an operation called a pneumonectomy.Sometimes part of the diaphragm, the muscle below thelungs that helps with breathing, is also removed. Radiation therapy, also called radiotherapy, involvesthe use of high-energy rays to kill cancer cells and shrinktumors. Radiation therapy affects the cancer cells only inthe treated area. The radiation may come from a machine(external radiation) or from putting materials thatproduce radiation through thin plastic tubes into the areawhere the cancer cells are found (internal radiationtherapy). Chemotherapy is the use of anticancer drugs to killcancer cells throughout the body. Most drugs used totreat mesothelioma are given by injection into a vein(intravenous, or IV). Doctors are also studying theeffectiveness of putting chemotherapy directly intothe chest or abdomen (intracavitary chemotherapy). To relieve symptoms and control pain, the doctor mayuse a needle or a thin tube to drain fluid that has builtup in the chest or abdomen. The procedure for removingfluid from the chest is called thoracentesis. Removal of fluidfrom the abdomen is called paracentesis. Drugs may begiven through a tube in the chest to prevent more fluidfrom accumulating. Radiation therapy and surgery mayalso be helpful in relieving symptoms. Are new treatments for mesothelioma being studied?
Sources of National Cancer Institute Information |
Sunday, July 24, 2005
Mesothelioma
