Definition of thyroid cancer: Cancer that forms in the thyroid gland (an organ at the base of the throat that
makes hormones that help control heart rate, blood pressure, body temperature, and weight). Four main types
of thyroid cancer are papillary, follicular, medullary, and anaplastic thyroid cancer. The four types are
based on how the cancer cells look under a microscope.
Four or more tiny parathyroid glands are behind the thyroid. They are on its surface. They make parathyroid hormone, which plays a big role in helping the body maintain a healthy level of calcium.
The pictures show the front and back of the thyroid.
Cancer CellsCancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.Normal, healthy cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells take their place. Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old or damaged cells do not die as they should. The build-up of extra cells often forms a mass of tissue called a growth or tumor. Growths on the thyroid are often called nodules. Most thyroid nodules (more than 90 percent) are benign (not cancer). Benign nodules are not as harmful as malignant nodules (cancer):
Cancer cells can spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells attach to other organs and grow to form new tumors that may damage those organs. The spread of cancer is called metastasis. See the "Staging" section for information about thyroid cancer that has spread.
Types of Thyroid CancerThere are several types of thyroid cancer:
Risk FactorsDoctors often cannot explain why one person develops thyroid cancer and another does not. However, it is clear that no one can catch thyroid cancer from another person. Research has shown that people with certain risk factors are more likely than others to develop thyroid cancer. A risk factor is something that may increase the chance of developing a disease. Studies have found the following risk factors for thyroid cancer:
Having one or more risk factors does not mean that a person will get thyroid cancer. Most people who have risk factors never develop cancer.
SymptomsEarly thyroid cancer often does not have symptoms. But as the cancer grows, symptoms may include:
Most often, these symptoms are not due to cancer. An infection, a benign goiter, or another health problem is usually the cause of these symptoms. Anyone with symptoms that do not go away in a couple of weeks should see a doctor to be diagnosed and treated as early as possible.
DiagnosisIf you have symptoms that suggest thyroid cancer, your doctor will help you find out whether they are from cancer or some other cause. Your doctor will ask you about your personal and family medical history. You may have one or more of the following tests:
Your doctor may take tissue for a biopsy in one of two ways:
You may want to ask your doctor these questions before having a biopsy:
StagingTo plan the best treatment, your doctor needs to learn the extent (stage) of the disease. Staging is a careful attempt to find out the size of the nodule, whether the cancer has spread, and if so, to what parts of the body. Thyroid cancer spreads most often to the lymph nodes, lungs, and bones. When cancer spreads from its original place to another part of the body, the new tumor has the same kind of cancer cells and the same name as the original cancer. For example, if thyroid cancer spreads to the lungs, the cancer cells in the lungs are actually thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer. For that reason, it's treated as thyroid cancer, not lung cancer. Doctors call the new tumor "distant" or metastatic disease. Staging may involve one or more of these tests:
Cancer stage at diagnosis, which refers to the extent of a cancer in the body, determines the treatment options and has a stong influence on the length of survival. In general, if the cancer if found only in the part of the body where it started it is localized (sometimes referred to as stage 1). If it has spread to a different part of the body, the stage is regional or distant. For thyroid cancer, 68.1% are diagnosed at the local stage. The 5-year survival for localized thyoroid cancer is 99.9%.
TreatmentPeople with thyroid cancer have many treatment options. Treatment usually begins within a few weeks after the diagnosis, but you will have time to talk with your doctor about treatment choices and get a second opinion. The choice of treatment depends on:
You and your doctor can work together to develop a treatment plan that meets your needs. Your doctor may refer you to a specialist who has experience treating thyroid cancer, or you may ask for a referral. An endocrinologist is a doctor who specializes in treating people who have hormone disorders. You may see a thyroidologist, an endocrinologist who specializes in treating diseases of the thyroid. You may have a team of specialists. Other specialists who treat thyroid cancer include surgeons, medical oncologists, and radiation oncologists . Your health care team may also include an oncology nurse and a registered dietitian. Your doctor can describe your treatment choices and the expected results. Thyroid cancer may be treated with surgery, thyroid hormone treatment, radioactive iodine therapy, external radiation therapy, or chemotherapy. Most patients receive a combination of treatments. For example, the standard treatment for papillary cancer is surgery, thyroid hormone treatment, and radioactive iodine therapy. Although external radiation therapy and chemotherapy are not often used, when they are, the treatments may be combined. Surgery and external radiation therapy are local therapies. They remove or destroy cancer in the thyroid. When thyroid cancer has spread to other parts of the body, local therapy may be used to control the disease in those specific areas. Thyroid hormone treatment, radioactive iodine therapy, and chemotherapy are systemic therapies. Systemic therapies enter the bloodstream and destroy or control cancer throughout the body. You may want to know about side effects and how treatment may change your normal activities. Because cancer treatments often damage healthy cells and tissues, side effects are common. Side effects depend mainly on the type and extent of the treatment. Side effects may not be the same for each person, and they may change from one treatment session to the next. Before treatment starts, ask your health care team to explain possible side effects and suggest ways to help you manage them. At any stage of disease, care is available to relieve the side effects of treatment, to control pain and other symptoms, and to help you cope with the feelings that a diagnosis of cancer can bring. Information about coping is available on NCI's Web site at http://www.cancer.gov/cancertopics/coping, and from Information Specialists at 1-800-4-CANCER or LiveHelp (http://www.cancer.gov/help). You may want to talk to your doctor about taking part in a clinical trial, a research study of new treatment methods. See "The Promise of Cancer Research" section. You may want to ask your doctor these questions before your treatment begins:
SurgeryMost people with thyroid cancer have surgery. The surgeon removes all or part of the thyroid. The type of surgery depends on the type and stage of thyroid cancer, the size of the nodule, and your age.
The time it takes to heal after surgery is different for each person. You may be uncomfortable for the first few days. Medicine can help control your pain. Before surgery, you should discuss the plan for pain relief with your doctor or nurse. After surgery, your doctor can adjust the plan if you need more pain relief. Surgery for thyroid cancer removes the cells that make thyroid hormone. After surgery, nearly all people need to take pills to replace the natural thyroid hormone. You will need thyroid hormone pills for the rest of your life. If the surgeon removes the parathyroid glands, you may need to take calcium and vitamin D pills for the rest of your life. In a few people, surgery may damage certain nerves or muscles. If this happens, a person may have voice problems or one shoulder may be lower than the other. You may want to ask your doctor these questions before having surgery:
Thyroid Hormone TreatmentAfter surgery to remove part or all of the thyroid, nearly everyone needs to take pills to replace the natural thyroid hormone. However, thyroid hormone pills are also used as part of the treatment for papillary or follicular thyroid cancer. Thyroid hormone slows the growth of thyroid cancer cells left in the body after surgery. Thyroid hormone pills seldom cause side effects. Your doctor gives you blood tests to make sure you're getting the right dose of thyroid hormone. Too much thyroid hormone may cause you to lose weight and feel hot and sweaty. It may also cause a fast heart rate, chest pain, cramps, and diarrhea. Too little thyroid hormone may cause you to gain weight, feel cold and tired, and have dry skin and hair. If you have side effects, your doctor can adjust your dose of thyroid hormone. You may want to ask your doctor these questions before taking thyroid hormone:
Radioactive Iodine TherapyRadioactive iodine (I-131) therapy is a treatment for papillary or follicular thyroid cancer. It kills thyroid cancer cells and normal thyroid cells that remain in the body after surgery. People with medullary thyroid cancer or anaplastic thyroid cancer usually do not receive I-131 therapy. These types of thyroid cancer rarely respond to I-131 therapy. Even people who are allergic to iodine can take I-131 therapy safely. The therapy is given as a liquid or capsule that you swallow. I-131 goes into the bloodstream and travels to thyroid cancer cells throughout the body. When thyroid cancer cells take in enough I-131, they die. Many people get I-131 therapy in a clinic or in the outpatient area of a hospital and can go home afterward. Some people have to stay in the hospital for one day or longer. Ask your health care team to explain how to protect family members and coworkers from being exposed to the radiation. Most radiation from I-131 is gone in about one week. Within three weeks, only traces of I-131 remain in the body. During treatment, you can help protect your bladder and other healthy tissues by drinking a lot of fluids. Drinking fluids helps I-131 pass out of the body faster. Some people have mild nausea the first day of I-131 therapy. A few people have swelling and pain in the neck where thyroid cells remain. If thyroid cancer cells have spread outside the neck, those areas may be painful too. You may have a dry mouth or lose your sense of taste or smell for a short time after I-131 therapy. Chewing sugar-free gum or sucking on sugar-free hard candy may help. A rare side effect in men who receive a high dose of I-131 is loss of fertility. In women, I-131 may not cause loss of fertility, but some doctors advise women to avoid getting pregnant for one year after a high dose of I-131. Researchers have reported that a very small number of patients may develop a second cancer years after treatment with a high dose of I-131. See the "Follow-up Care" section for information about checkups after treatment. A high dose of I-131 also kills normal thyroid cells, which make thyroid hormone. After radioactive iodine therapy, you need to take thyroid hormone pills to replace the natural hormone. You may wish to read the NCI fact sheet Radiation Therapy for Cancer: Questions and Answers. You may want to ask your doctor these questions before having radioactive iodine therapy:
External Radiation TherapyExternal radiation therapy (also called radiotherapy) is a treatment for any type of thyroid cancer that can't be treated with surgery or I-131 therapy. It's also used for cancer that returns after treatment or to treat bone pain from cancer that has spread. External radiation therapy uses high-energy rays to kill cancer cells. A large machine directs radiation at the neck or other tissues where cancer has spread. Most patients go to the hospital or clinic for their treatment, usually 5 days a week for several weeks. Each treatment takes only a few minutes. The side effects depend mainly on how much radiation is given and which part of your body is treated. Radiation to the neck may cause a dry, sore mouth and throat, hoarseness, or trouble swallowing. Your skin in the treated area may become red, dry, and tender. You are likely to become tired during radiation therapy, especially in the later weeks of treatment. Resting is important, but doctors usually advise patients to try to stay as active as they can. Although the side effects of radiation therapy can be distressing, your doctor can usually treat or control them. The side effects usually go away after treatment ends. You may wish to read the NCI booklet Radiation Therapy and You. You may want to ask your doctor these questions about external radiation therapy:
ChemotherapyChemotherapy is a treatment for anaplastic thyroid cancer. It's sometimes used to relieve symptoms of medullary thyroid cancer or other thyroid cancers. Chemotherapy uses drugs to kill cancer cells. The drugs are usually given by injection into a vein. They enter the bloodstream and can affect cancer cells all over the body. You may have treatment in a clinic, at the doctor's office, or at home. Some people may need to stay in the hospital during treatment. The side effects of chemotherapy depend mainly on which drugs and how much are given. The drugs can harm normal cells that divide rapidly, such as the cells in the mouth. The most common side effects include nausea, vomiting, mouth sores, loss of appetite, and hair loss. Your health care team can suggest ways to control many of these side effects. Most side effects go away after treatment ends. You may wish to read the NCI booklet Chemotherapy and You: Support for People With Cancer. You may want to ask your doctor these questions about chemotherapy:
Second OpinionBefore starting treatment, you might want a second opinion about your diagnosis and treatment plan. Many insurance companies cover a second opinion if you or your doctor requests it. A second opinion can make you feel more confident about the diagnosis and treatment choices. It may take some time and effort to gather your medical records and see another doctor. In most cases, it's not a problem to take several weeks to get a second opinion. The delay in starting treatment usually will not make treatment less effective. To make sure, you should discuss any delay with your doctor. There are many ways to find a doctor for a second opinion. You can ask your doctor, a local or state medical society, a nearby hospital, or a medical school for names of specialists. Other sources can be found in NCI's fact sheet How To Find a Doctor or Treatment Facility If You Have Cancer.
Follow-up CareYou need regular checkups after treatment for thyroid cancer. Even when there are no longer any signs of cancer, the disease sometimes returns because cancer cells remained somewhere in the body after treatment. Your doctor monitors your recovery and checks for return of the cancer with blood tests and imaging tests. If thyroid cancer returns, it is most commonly found in the neck, lungs, or bones. Also, checkups help detect health problems that can result from cancer treatment. People treated with radioactive iodine therapy or external radiation therapy have an increased chance of developing other cancers later on. If you have any health problems between checkups, you should contact your doctor. People treated for papillary or follicular thyroid cancer have blood tests to check the levels of TSH and thyroglobulin. Thyroid hormone is normally stored in the thyroid as thyroglobulin. If the whole thyroid has been removed, there should be very little or no thyroglobulin in the blood. A high level of thyroglobulin may mean that thyroid cancer has returned. Your doctor helps you get ready for a thyroglobulin test in one of two ways:
People treated for medullary thyroid cancer have blood tests to check the level of calcitonin and other substances. In addition to blood tests, checkups may include one or more of the following imaging tests:
You may want to read the NCI booklet Facing Forward: Life After Cancer Treatment. It answers questions about follow-up care and other concerns. You may want to ask your doctor these questions after you have finished treatment:
Sources of SupportLearning that you have a serious disease such as thyroid cancer is not easy. You may worry about caring for your family, keeping your job, or continuing daily activities. Concerns about treatments and managing side effects, hospital stays, and medical bills are also common.It may help to share your feelings with family, friends, a member of your health care team, or another person with cancer. Here's where you can go for support:
The Promise of Cancer ResearchDoctors all over the country are conducting many types of clinical trials (research studies in which people volunteer to take part). Clinical trials are designed to answer important questions and to find out whether new approaches are safe and effective. Research already has led to advances in the diagnosis and treatment of thyroid cancer. Researchers continue to search for new and better ways to treat thyroid cancer. People who join clinical trials may be among the first to benefit if a new approach is effective. And even if the people in a trial do not benefit directly, they may still make an important contribution by helping doctors learn more about thyroid cancer and how to control it. Although clinical trials may pose some risks, researchers do all they can to protect their patients. NCI's Web site includes a section on clinical trials. It has general information about clinical trials as well as detailed information about specific ongoing studies of thyroid cancer. NCI's Information Specialists at 1-800-4-CANCER or at LiveHelp can answer questions and provide information about clinical trials. If you're interested in taking part in a clinical trial, talk with your doctor. You may also want to read the NCI booklet Taking Part in Cancer Treatment Research Studies. This booklet describes how treatment studies are carried out and explains their possible benefits and risks. Another agency of the Federal Government, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), conducts research on diseases of the thyroid. NIDDK performs laboratory studies and conducts clinical trials on thyroid cancer. See the Web site of NIDDK. You can find NCI and NIDDK clinical trials. This Web site provides the latest information about federally and privately supported clinical trials.
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