Cancer: Questions and Answers

About 1.4 million new cases of cancer will be diagnosed in the United States in 2005, and more than 550,000 people will die of the disease (1). Cancer is the second leading cause of death in this country. However, improvements in cancer detection, diagnosis, and treatment have increased the survival rate for many types of cancer. About 64 percent of all people diagnosed with cancer will be alive 5 years after diagnosis (1).

1. What is cancer?

   Cancer is a group of many related diseases that begin in cells, the body's basic building blocks. To understand cancer, it is helpful to know what happens when normal cells become cancerous.

   The body is made up of many types of cells. Normally, cells grow and divide to produce more cells as they are needed to keep the body healthy. Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. The extra cells form a mass of tissue called a growth or tumor. Not all tumors are cancerous; tumors can be benign or malignant.

   Benign tumors are not cancer. They can often be removed and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body. Most important, benign tumors are rarely a threat to life.

   Malignant tumors are cancer. Cells in malignant tumors are abnormal and divide without control or order. Cancer cells invade and destroy the tissue around them. Cancer cells can also break away from a malignant tumor and enter the bloodstream or lymphatic system.

   Blood vessels include a network of arteries, capillaries, and veins through which the blood circulates in the body. The lymphatic system carries lymph and white blood cells through lymphatic vessels (thin tubes) to all the tissues of the body. By moving through the bloodstream or lymphatic system, cancer can spread from the primary (original) cancer site to form new tumors in other organs. The spread of cancer is called metastasis.

2. What causes cancer?

   Scientists have learned that cancer is caused by changes in genes that normally control the growth and death of cells. Certain lifestyle and environmental factors can change some normal genes into genes that allow the growth of cancer. Many gene changes that lead to cancer are the result of tobacco use, diet, exposure to ultraviolet (UV) radiation from the sun, or exposure to carcinogens (cancer-causing substances) in the workplace or in the environment. Some gene alterations are inherited (from one or both parents). However, having an inherited gene alteration does not always mean that the person will develop cancer; it only means that the chance of getting cancer is increased. Scientists continue to examine the factors that may increase or decrease a person's chance of developing cancer.

   Although being infected with certain viruses, such as the human papillomavirus (HPV), hepatitis B and C (HepB and HepC), and human immunodeficiency virus (HIV), increases the risk of some types of cancer, cancer itself is not contagious. A person cannot catch cancer from someone who has this disease. Scientists also know that an injury or bruise does not cause cancer.

3. Can cancer be prevented?

   Although there is no guaranteed way to prevent cancer, people can reduce their risk (chance) of developing cancer by:

   • not using tobacco products
   • choosing foods with less fat and eating more vegetables, fruits, and whole grains
   • exercising regularly and maintaining a lean weight
   • avoiding the harmful rays of the sun, using sunscreen, and wearing clothing that protects the skin
   • talking with a doctor about the possible benefits of drugs proven to reduce the risk of certain cancers

   Although many risk factors can be avoided, some, such as inherited conditions, are unavoidable. Still, it is helpful to be aware of them. It is also important to keep in mind that not everyone with a particular risk factor for cancer actually gets the disease; in fact, most do not. People who have an increased likelihood of developing cancer can help protect themselves by avoiding risk factors (see Question 2) whenever possible and by getting regular checkups so that, if cancer develops, it is likely to be found and treated early. Treatment is often more effective when cancer is detected early. Screening exams, such as sigmoidoscopy or the fecal occult blood test, mammography, and the Pap test, can detect precancerous conditions (which can be treated before they turn into cancer) and early-stage cancer.

   The NCI is conducting many cancer prevention studies to explore ways to reduce the risk of developing cancer. These studies are evaluating dietary supplements, chemopreventive agents, nutrition, personal behaviors, and other factors that may prevent cancer. More information about cancer prevention trials is available in the following NCI resources:

   • Breast Cancer Prevention Studies
     (http://www.cancer.gov/cancertopics/factsheet/Prevention/breast-cancer)
   • Selenium and Vitamin E Cancer Prevention Trial (SELECT): Questions and Answers
     (http://www.cancer.gov/cancertopics/factsheet/Prevention/SELECT)
   • The Study of Tamoxifen and Raloxifene (STAR): Questions and Answers
     (http://www.cancer.gov/cancertopics/factsheet/STARresultsQandA).

   See Question 6 for additional information about clinical trials related to the prevention, screening, diagnosis, and treatment of cancer.

4. What are some of the common signs and symptoms of cancer?

   Cancer can cause a variety of symptoms. Possible signs of cancer include the following:

   • new thickening or lump in the breast or any other part of the body
   • new mole or an obvious change in the appearance of an existing wart or mole
   • a sore that does not heal
   • nagging cough or hoarseness
   • changes in bowel or bladder habits
   • persistent indigestion or difficulty swallowing
   • unexplained changes in weight
   • unusual bleeding or discharge

   When these or other symptoms occur, they are not always caused by cancer. They can be caused by infections, benign tumors, or other problems. It is important to see a doctor about any of these symptoms or about other physical changes. Only a doctor can make a diagnosis. A person with these or other symptoms should not wait to feel pain because early cancer usually does not cause pain.

   If symptoms occur, the doctor may perform a physical examination, order blood work and other tests, and/or recommend a biopsy. In most cases, a biopsy is the only way to know for certain whether cancer is present. During a biopsy, the doctor removes a sample of tissue from the abnormal area. A pathologist studies the tissue under a microscope to identify cancer cells.

5. How is cancer treated?

   Cancer treatment can include surgery, radiation therapy, chemotherapy, hormone therapy, and biological therapy. The doctor may use one method or a combination of methods, depending on the type and location of the cancer, whether the disease has spread, the patient's age and general health, and other factors. Because treatment for cancer can also damage healthy cells and tissues, it often causes side effects. Some patients may worry that the side effects of treatment are worse than the disease. However, patients and doctors generally discuss the treatment options, weighing the likely benefits of killing cancer cells and the risks of possible side effects. Doctors can suggest ways to reduce or eliminate problems that may occur during and after treatment.

   Surgery is an operation to remove cancer. The side effects of surgery depend on many factors, including the size and location of the tumor, the type of operation, and the patient's general health. Patients have some pain after surgery, but this pain can be controlled with medicine. It is also common for patients to feel tired or weak for a while after surgery.

   Patients may worry that having a biopsy or other type of surgery for cancer will spread the disease. This is a very rare occurrence because surgeons take special precautions to prevent cancer from spreading during surgery. Also, exposing cancer to air during surgery does not cause the disease to spread.

   Radiation therapy (also called radiotherapy) uses high-energy rays to kill cancer cells in a targeted area. Radiation can be given externally by a machine that aims radiation at the tumor area. It can also be given internally; needles, seeds, wires, or catheters containing a radioactive substance are placed directly in or near the tumor. Radiation treatments are painless. The side effects are usually temporary, and most can be treated or controlled. Patients are likely to feel very tired, especially in the later weeks of treatment. Radiation therapy may also cause a decrease in the number of white blood cells, which help protect the body against infection. With external radiation, it is also common to have temporary hair loss in the treated area and for the skin to become red, dry, tender, and itchy.

   There is no risk of radiation exposure from coming in contact with a patient undergoing external radiation therapy. External radiation does not cause the body to become radioactive. With internal radiation (also called implant radiation), a patient may need to stay in the hospital, away from other people, while the radiation level is highest. Implants may be permanent or temporary. The amount of radiation in a permanent implant goes down to a safe level before the person leaves the hospital. With a temporary implant, there is no radioactivity left in the body after the implant is removed.

   Chemotherapy is the use of drugs that kill cancer cells throughout the body. Healthy cells can also be harmed, especially those that divide quickly. The doctor may use one drug or a combination of drugs. The side effects of chemotherapy depend mainly on the drug(s) and the dose(s) the patient receives. Hair loss is a common side effect of chemotherapy; however, not all anticancer drugs cause loss of hair. Anticancer drugs may also cause temporary fatigue, poor appetite, nausea and vomiting, diarrhea, and mouth and lip sores. Drugs that prevent or reduce nausea and vomiting can help with some of these side effects. Normal cells usually recover when chemotherapy is over, so most side effects gradually go away after treatment ends.

   Hormone therapy is used to treat certain cancers that depend on hormones for their growth. It works by keeping cancer cells from getting or using the hormones they need to grow. This treatment may include the use of drugs that stop the production of certain hormones or that change the way hormones work. Another type of hormone therapy is surgery to remove organs that make hormones. For example, the ovaries may be removed to treat breast cancer, or the testicles may be removed to treat prostate cancer.

   Hormone therapy can cause a number of side effects. Patients may feel tired, or have fluid retention, weight gain, hot flashes, nausea and vomiting, changes in appetite, and, in some cases, blood clots. Hormone therapy may also cause bone loss in premenopausal women. Depending on the type of hormone therapy used, these side effects may be temporary, long lasting, or permanent.

   Biological therapy uses the body's immune system, directly or indirectly, to fight disease and to lessen some of the side effects of cancer treatment. Monoclonal antibodies, interferon, interleukin-2, and colony-stimulating factors are some types of biological therapy.

   The side effects caused by biological therapy vary with the specific treatment. In general, these treatments tend to cause flu-like symptoms, such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Patients also may bleed or bruise easily, get a skin rash, or have swelling. These problems can be severe, but they go away after the treatment stops.

6. Are clinical trials (research studies) available? Where can people get more information about clinical trials?

   Yes. Clinical trials are an important treatment option for many cancer patients. To develop new, more effective treatments, and better ways to use current treatments, the NCI is sponsoring clinical trials in many hospitals and cancer centers around the country. Clinical trials are a critical step in the development of new methods of treatment. Before any new treatment can be recommended for general use, doctors conduct clinical trials to find out whether the treatment is safe for patients and effective against the disease.

   People interested in taking part in a clinical trial should talk with their doctor. Information about clinical trials is available from the NCI's Cancer Information Service (CIS) (see below) at 1–800–4–CANCER and in the NCI booklet Taking Part in Cancer Treatment Research Studies, which is available at http://www.cancer.gov/publications on the Internet. This booklet describes how research studies are carried out and explains their possible benefits and risks. Further information about clinical trials is available at http://www.cancer.gov/clinicaltrials on the NCI's Web site. The Web site offers detailed information about specific ongoing treatment trials as well as trials focused on prevention, screening, and diagnosis by linking to PDQ®, the NCI's comprehensive cancer information database. The CIS also provides information from PDQ.

7. Does cancer always cause pain?

   Having cancer does not always mean having pain. Whether a patient has pain may depend on the type of cancer, the extent of the disease, and the patient's tolerance for pain. Most pain occurs when the cancer grows and presses against bones, organs, or nerves. Pain may also be a side effect of treatment. However, pain can generally be relieved or reduced with prescription medicines or over-the-counter drugs recommended by the doctor. Other ways to reduce pain, such as relaxation exercises, may also be useful. Pain should not be accepted as an unavoidable part of having cancer. It is important for patients to talk about pain so steps can be taken to help relieve it. The fear of addiction or “losing control” should not stop patients from taking pain medication. Patients who take medications for cancer pain, as prescribed by their doctor, rarely become addicted to them. In addition, changing the dose or type of medication can usually help if the patient has troublesome side effects.

Selected Reference

1. American Cancer Society, Inc. Cancer Facts and Figures 2005. Atlanta: American Cancer Society, Inc., 2005. Also available at http://www.cancer.org/downloads/STT/CAFF2005f4PWSecured.pdf on the Internet.

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Bone Cancer: Questions and Answers

1. What is bone cancer?

   Bone cancer is a malignant (cancerous) tumor of the bone that destroys normal bone tissue (1). Not all bone tumors are malignant. In fact, benign (noncancerous) bone tumors are more common than malignant ones. Both malignant and benign bone tumors may grow and compress healthy bone tissue, but benign tumors do not spread, do not destroy bone tissue, and are rarely a threat to life.

   Malignant tumors that begin in bone tissue are called primary bone cancer. Cancer that metastasizes (spreads) to the bones from other parts of the body, such as the breast, lung, or prostate, is called metastatic cancer, and is named for the organ or tissue in which it began. Primary bone cancer is far less common than cancer that spreads to the bones.
   

2. Are there different types of primary bone cancer?

   Yes. Cancer can begin in any type of bone tissue. Bones are made up of osteoid (hard or compact), cartilaginous (tough, flexible), and fibrous (threadlike) tissue, as well as elements of bone marrow (soft, spongy tissue in the center of most bones).

   Common types of primary bone cancer include:
   
   

   • Osteosarcoma, which arises from osteoid tissue in the bone. This tumor occurs most often in the knee and upper arm (1).
     
     
   • Chondrosarcoma, which begins in cartilaginous tissue. Cartilage pads the ends of bones and lines the joints. Chondrosarcoma occurs most often in the pelvis (located between the hip bones), upper leg, and shoulder. Sometimes a chondrosarcoma contains cancerous bone cells. In that case, doctors classify the tumor as an osteosarcoma.
     
     
   • The Ewing Sarcoma Family of Tumors (ESFTs), which usually occur in bone but may also arise in soft tissue (muscle, fat, fibrous tissue, blood vessels, or other supporting tissue). Scientists think that ESFTs arise from elements of primitive nerve tissue in the bone or soft tissue (2). ESFTs occur most commonly along the backbone and pelvis and in the legs and arms (3).
     
     Other types of cancer that arise in soft tissue are called soft tissue sarcomas. They are not bone cancer and are not described in this resource. (More information about these types of cancer is available in the NCI fact sheet Soft Tissue Sarcomas: Questions and Answers at http://www.cancer.gov/cancertopics/factsheet/Sites-Types/soft-tissue-sarcoma on the Internet.)
     
     
3. What are the possible causes of bone cancer?

   Although bone cancer does not have a clearly defined cause, researchers have identified several factors that increase the likelihood of developing these tumors. Osteosarcoma occurs more frequently in people who have had high-dose external radiation therapy or treatment with certain anticancer drugs; children seem to be particularly susceptible. A small number of bone cancers are due to heredity. For example, children who have had hereditary retinoblastoma (an uncommon cancer of the eye) are at a higher risk of developing osteosarcoma, particularly if they are treated with radiation. Additionally, people who have hereditary defects of bones and people with metal implants, which doctors sometimes use to repair fractures, are more likely to develop osteosarcoma (4). Ewing sarcoma is not strongly associated with any heredity cancer syndromes, congenital childhood diseases, or previous radiation exposure (2).
   

4. How often does bone cancer occur?

   Primary bone cancer is rare. It accounts for much less than 1 percent of all cancers. About 2,300 new cases of primary bone cancer are diagnosed in the United States each year (5). Different types of bone cancer are more likely to occur in certain populations:

   • Osteosarcoma occurs most commonly between ages 10 and 19. However, people over age 40 who have other conditions, such as Paget disease (a benign condition characterized by abnormal development of new bone cells), are at increased risk of developing this cancer.
     
     
   • Chondrosarcoma occurs mainly in older adults (over age 40). The risk increases with advancing age. This disease rarely occurs in children and adolescents
     
     
   • ESFTs occur most often in children and adolescents under 19 years of age. Boys are affected more often than girls. These tumors are extremely rare in African American children.
     
     
5. What are the symptoms of bone cancer?

   Pain is the most common symptom of bone cancer, but not all bone cancers cause pain (1). Persistent or unusual pain or swelling in or near a bone can be caused by cancer or by other conditions. It is important to see a doctor to determine the cause.

6. How is bone cancer diagnosed?

   To help diagnose bone cancer, the doctor asks about the patient’s personal and family medical history. The doctor also performs a physical examination and may order laboratory and other diagnostic tests. These tests may include (1):

   • X-rays, which can show the location, size, and shape of a bone tumor. If x-rays suggest that an abnormal area may be cancer, the doctor is likely to recommend special imaging tests. Even if x-rays suggest that an abnormal area is benign, the doctor may want to do further tests, especially if the patient is experiencing unusual or persistent pain.
     
     
     • A bone scan, which is a test in which a small amount of radioactive material is injected into a blood vessel and travels through the bloodstream; it then collects in the bones and is detected by a scanner.
       
       
     • A computed tomography (CT or CAT) scan, which is a series of detailed pictures of areas inside the body, taken from different angles, that are created by a computer linked to an x-ray machine.
       
       
     • A magnetic resonance imaging (MRI) procedure, which uses a powerful magnet linked to a computer to create detailed pictures of areas inside the body without using x-rays.
       
       
     • A positron emission tomography (PET) scan, in which a small amount of radioactive glucose (sugar) is injected into a vein, and a scanner is used to make detailed, computerized pictures of areas inside the body where the glucose is used. Because cancer cells often use more glucose than normal cells, the pictures can be used to find cancer cells in the body.
       
       
     • An angiogram, which is an x-ray of blood vessels.
       
       
   • Biopsy (removal of a tissue sample from the bone tumor) to determine whether cancer is present. The surgeon may perform a needle biopsy or an incisional biopsy. During a needle biopsy, the surgeon makes a small hole in the bone and removes a sample of tissue from the tumor with a needle-like instrument. In an incisional biopsy, the surgeon cuts into the tumor and removes a sample of tissue. Biopsies are best done by an orthopedic oncologist (a doctor experienced in the treatment of bone cancer) (1). A pathologist (a doctor who identifies disease by studying cells and tissues under a microscope) examines the tissue to determine whether it is cancerous.
     
     
   • Blood tests to determine the level of an enzyme called alkaline phosphatase. A large amount of this enzyme is present in the blood when the cells that form bone tissue are very active—when children are growing, when a broken bone is mending, or when a disease or tumor causes production of abnormal bone tissue. Because high levels of alkaline phosphatase are normal in growing children and adolescents, this test is not a completely reliable indicator of bone cancer (1, 6) .
     
     
7. What are the treatment options for bone cancer?

   Treatment options depend on the type, size, location, and stage of the cancer, as well as the person’s age and general health. Treatment options for bone cancer include surgery, chemotherapy, radiation therapy, and cryosurgery.

   • Surgery is the usual treatment for bone cancer. The surgeon removes the entire tumor with negative margins (no cancer cells are found at the edge or border of the tissue removed during surgery). The surgeon may also use special surgical techniques to minimize the amount of healthy tissue removed with the tumor.
     
     

     Dramatic improvements in surgical techniques and preoperative tumor treatment have made it possible for most patients with bone cancer in an arm or leg to avoid radical surgical procedures (removal of the entire limb). However, most patients who undergo limb-sparing surgery need reconstructive surgery to maximize limb function (1).

   • Chemotherapy is the use of anticancer drugs to kill cancer cells. Patients who have bone cancer usually receive a combination of anticancer drugs. However, chemotherapy is not currently used to treat chondrosarcoma (1).
     
     
   • Radiation therapy, also called radiotherapy, involves the use of high-energy x-rays to kill cancer cells. This treatment may be used in combination with surgery. It is often used to treat chondrosarcoma, which cannot be treated with chemotherapy, as well as ESFTs (1). It may also be used for patients who refuse surgery.
     
     
   • Cryosurgery is the use of liquid nitrogen to freeze and kill cancer cells. This technique can sometimes be used instead of conventional surgery to destroy the tumor (1).
     
     
8. Is follow-up treatment necessary? What does it involve?

   Yes. Bone cancer sometimes metastasizes, particularly to the lungs, or can recur (come back), either at the same location or in other bones in the body (1). People who have had bone cancer should see their doctor regularly and should report any unusual symptoms right away. Follow-up varies for different types and stages of bone cancer. Generally, patients are checked frequently by their doctor and have regular blood tests and x-rays. People who have had bone cancer, particularly children and adolescents, have an increased likelihood of developing another type of cancer, such as leukemia, later in life. Regular follow-up care ensures that changes in health are discussed and that problems are treated as soon as possible.
   

9. Are clinical trials (research studies) available for people with bone cancer?

   Yes. Participation in clinical trials is an important treatment option for many people with bone cancer. To develop new treatments and better ways to use current treatments, the National Cancer Institute (NCI), a part of the National Institutes of Health, is sponsoring clinical trials in many hospitals and cancer centers around the country. Clinical trials are a critical step in the development of new methods of treatment. Before any new treatment can be recommended for general use, doctors conduct clinical trials to find out whether the treatment is safe for patients and effective against the disease.

   People interested in taking part in a clinical trial should talk with their doctor. Information about clinical trials is available from the NCI’s Cancer Information Service (CIS) (see below) at 1–800–4–CANCER and in the NCI booklet Taking Part in Cancer Treatment Research Studies, which can be found at http://www.cancer.gov/clinicaltrials/Taking-Part-in-Cancer-Treatment-Research-Studies on the Internet. This booklet describes how research studies are carried out and explains their possible benefits and risks. Further information about clinical trials is available at http://www.cancer.gov/clinicaltrials on the NCI’s Web site. The Web site offers detailed information about specific ongoing studies by linking to PDQ®, the NCI’s comprehensive cancer information database. The CIS also provides information from PDQ.
   

Selected References

1. Malawer MM, Helman LJ, O'Sullivan B. Sarcomas of bone. In: DeVita VT, Hellman S, Rosenberg SA, editors. Cancer: Principles and Practice of Oncology. Vol. 2. 7th ed. Philadelphia: Lippincott Williams and Wilkins, 2004.
   
   
2. Pizzo P, Poplack DG, editors. Principles and Practice of Pediatric Oncology. 4th ed. Philadelphia: Lippincott Williams and Wilkins, 2002.
   
   
3. Ries LAG, Smith MA, Gurney JG, et al., editors. Cancer Incidence and Survival among Children and Adolescents: United States SEER Program 1975-1999. Bethesda, MD: National Cancer Institute, 1999.
   
   
4. Miller RW, Boice JD, Curtis RE. Bone cancer. In: Schottenfeld D, Fraumeni JF, editors. Cancer Epidemiology and Prevention. 2nd ed. New York: Oxford University Press, 1996.
   
   
5. American Cancer Society (2008). Cancer Facts and Figures 2008. Atlanta, GA: American Cancer Society. Retrieved March 13, 2008, from http://www.cancer.org/downloads/STT/2008CAFFfinalsecured.pdf.
   
   
6. Fischbach FT, Dunning MB. A Manual of Laboratory and Diagnostic Tests. 7th ed. Philadelphia: Lippincott Williams and Wilkins, 2004.

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Posted in: Bone Cancer: Questions and Answers

Mesothelioma: Questions and Answers

Mesothelioma: Questions and Answers

Mesothelioma is a rare form of cancer in which malignant (cancerous) cells are found in the mesothelium, a protective sac that covers most of the body's internal organs. Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles.

1. What is the mesothelium?
   
   The mesothelium is a membrane that covers and protects most of the internal organs of the body. It is composed of two layers of cells: One layer immediately surrounds the organ; the other forms a sac around it. The mesothelium produces a lubricating fluid that is released between these layers, allowing moving organs (such as the beating heart and the expanding and contracting lungs) to glide easily against adjacent structures.
   
   The mesothelium has different names, depending on its location in the body. The peritoneum is the mesothelial tissue that covers most of the organs in the abdominal cavity. The pleura is the membrane that surrounds the lungs and lines the wall of the chest cavity. The pericardium covers and protects the heart. The mesothelial tissue surrounding the male internal reproductive organs is called the tunica vaginalis testis. The tunica serosa uteri covers the internal reproductive organs in women.
   
   
2. What is mesothelioma?
   
   Mesothelioma (cancer of the mesothelium) is a disease in which cells of the mesothelium become abnormal and divide without control or order. They can invade and damage nearby tissues and organs. Cancer cells can also metastasize (spread) from their original site to other parts of the body. Most cases of mesothelioma begin in the pleura or peritoneum.
   
   
3. How common is mesothelioma?
   
   Although reported incidence rates have increased in the past 20 years, mesothelioma is still a relatively rare cancer. About 2,000 new cases of mesothelioma are diagnosed in the United States each year. Mesothelioma occurs more often in men than in women and risk increases with age, but this disease can appear in either men or women at any age.
   
   
4. What are the risk factors for mesothelioma?
   
   Working with asbestos is the major risk factor for mesothelioma. A history of asbestos exposure at work is reported in about 70 percent to 80 percent of all cases. However, mesothelioma has been reported in some individuals without any known exposure to asbestos.
   
   Asbestos is the name of a group of minerals that occur naturally as masses of strong, flexible fibers that can be separated into thin threads and woven. Asbestos has been widely used in many industrial products, including cement, brake linings, roof shingles, flooring products, textiles, and insulation. If tiny asbestos particles float in the air, especially during the manufacturing process, they may be inhaled or swallowed, and can cause serious health problems. In addition to mesothelioma, exposure to asbestos increases the risk of lung cancer, asbestosis (a noncancerous, chronic lung ailment), and other cancers, such as those of the larynx and kidney.
   
   Smoking does not appear to increase the risk of mesothelioma. However, the combination of smoking and asbestos exposure significantly increases a person's risk of developing cancer of the air passageways in the lung.
   
   
5. Who is at increased risk for developing mesothelioma?
   
   Asbestos has been mined and used commercially since the late 1800s. Its use greatly increased during World War II. Since the early 1940s, millions of American workers have been exposed to asbestos dust. Initially, the risks associated with asbestos exposure were not known. However, an increased risk of developing mesothelioma was later found among shipyard workers, people who work in asbestos mines and mills, producers of asbestos products, workers in the heating and construction industries, and other tradespeople. Today, the U.S. Occupational Safety and Health Administration (OSHA) sets limits for acceptable levels of asbestos exposure in the workplace. People who work with asbestos wear personal protective equipment to lower their risk of exposure.
   
   The risk of asbestos-related disease increases with heavier exposure to asbestos and longer exposure time. However, some individuals with only brief exposures have developed mesothelioma. On the other hand, not all workers who are heavily exposed develop asbestos-related diseases.
   
   There is some evidence that family members and others living with asbestos workers have an increased risk of developing mesothelioma, and possibly other asbestos-related diseases. This risk may be the result of exposure to asbestos dust brought home on the clothing and hair of asbestos workers. To reduce the chance of exposing family members to asbestos fibers, asbestos workers are usually required to shower and change their clothing before leaving the workplace.
   
   
6. What are the symptoms of mesothelioma?
   
   Symptoms of mesothelioma may not appear until 30 to 50 years after exposure to asbestos. Shortness of breath and pain in the chest due to an accumulation of fluid in the pleura are often symptoms of pleural mesothelioma. Symptoms of peritoneal mesothelioma include weight loss and abdominal pain and swelling due to a buildup of fluid in the abdomen. Other symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia, and fever. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face.
   
   These symptoms may be caused by mesothelioma or by other, less serious conditions. It is important to see a doctor about any of these symptoms. Only a doctor can make a diagnosis.
   
   
7. How is mesothelioma diagnosed?
   
   Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history, including any history of asbestos exposure. A complete physical examination may be performed, including x-rays of the chest or abdomen and lung function tests. A CT (or CAT) scan or an MRI may also be useful. A CT scan is a series of detailed pictures of areas inside the body created by a computer linked to an x-ray machine. In an MRI, a powerful magnet linked to a computer is used to make detailed pictures of areas inside the body. These pictures are viewed on a monitor and can also be printed.
   
   A biopsy is needed to confirm a diagnosis of mesothelioma. In a biopsy, a surgeon or a medical oncologist (a doctor who specializes in diagnosing and treating cancer) removes a sample of tissue for examination under a microscope by a pathologist. A biopsy may be done in different ways, depending on where the abnormal area is located. If the cancer is in the chest, the doctor may perform a thoracoscopy. In this procedure, the doctor makes a small cut through the chest wall and puts a thin, lighted tube called a thoracoscope into the chest between two ribs. Thoracoscopy allows the doctor to look inside the chest and obtain tissue samples. If the cancer is in the abdomen, the doctor may perform a peritoneoscopy. To obtain tissue for examination, the doctor makes a small opening in the abdomen and inserts a special instrument called a peritoneoscope into the abdominal cavity. If these procedures do not yield enough tissue, more extensive diagnostic surgery may be necessary.
   
   If the diagnosis is mesothelioma, the doctor will want to learn the stage (or extent) of the disease. Staging involves more tests in a careful attempt to find out whether the cancer has spread and, if so, to which parts of the body. Knowing the stage of the disease helps the doctor plan treatment.
   
   Mesothelioma is described as localized if the cancer is found only on the membrane surface where it originated. It is classified as advanced if it has spread beyond the original membrane surface to other parts of the body, such as the lymph nodes, lungs, chest wall, or abdominal organs.
   
   
8. How is mesothelioma treated?
   
   Treatment for mesothelioma depends on the location of the cancer, the stage of the disease, and the patient's age and general health. Standard treatment options include 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 chest or abdomen and some of the tissue around it. For cancer of the pleura (pleural mesothelioma), a lung may be removed in an operation called a pneumonectomy. Sometimes part of the diaphragm, the muscle below the lungs that helps with breathing, is also removed.
     
     
   • Radiation therapy, also called radiotherapy, involves the use of high-energy rays to kill cancer cells and shrink tumors. Radiation therapy affects the cancer cells only in the treated area. The radiation may come from a machine (external radiation) or from putting materials that produce radiation through thin plastic tubes into the area where the cancer cells are found (internal radiation therapy).
     
     
   • Chemotherapy is the use of anticancer drugs to kill cancer cells throughout the body. Most drugs used to treat mesothelioma are given by injection into a vein (intravenous, or IV). Doctors are also studying the effectiveness of putting chemotherapy directly into the chest or abdomen (intracavitary chemotherapy).
     
   
   To relieve symptoms and control pain, the doctor may use a needle or a thin tube to drain fluid that has built up in the chest or abdomen. The procedure for removing fluid from the chest is called thoracentesis. Removal of fluid from the abdomen is called paracentesis. Drugs may be given through a tube in the chest to prevent more fluid from accumulating. Radiation therapy and surgery may also be helpful in relieving symptoms.
   
   
9. Are new treatments for mesothelioma being studied?
   
   Yes. Because mesothelioma is very hard to control, the National Cancer Institute (NCI) is sponsoring clinical trials (research studies with people) that are designed to find new treatments and better ways to use current treatments. Before any new treatment can be recommended for general use, doctors conduct clinical trials to find out whether the treatment is safe for patients and effective against the disease. Participation in clinical trials is an important treatment option for many patients with mesothelioma.
   
   People interested in taking part in a clinical trial should talk with their doctor. Information about clinical trials is available from the Cancer Information Service (CIS) (see below) at 1–800–4–CANCER. Information specialists at the CIS use PDQ®, NCI's cancer information database, to identify and provide detailed information about specific ongoing clinical trials. Patients also have the option of searching for clinical trials on their own. The clinical trials page on the NCI's Cancer.gov Web site, located at http://www.cancer.gov/clinicaltrials on the Internet, provides general information about clinical trials and links to PDQ.
   
   People considering clinical trials may be interested in the NCI booklet Taking Part in Cancer Treatment Research Studies. This booklet describes how research studies are carried out and explains their possible benefits and risks. The booklet is available by calling the CIS, or from the NCI Publications Locator Web site at http://www.cancer.gov/publications on the Internet.

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