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Ask The Expert/FAQsMain | About Us | Ask The Expert | News | Events
A. Thyroid cancer is the most common cancer of the endocrine system. In 2008, 37,340 cases were diagnosed; of these, about 40 percent occurred in young adults (20-39 yrs). Differentiated thyroid carcinomas, including papillary and follicular thyroid carcinoma, make up 95 percent of cancers in this age group. The remaining 5 percent is primarily made up of medullary thyroid carcinoma. A fourth type of thyroid cancer, anaplastic thyroid cancer, is exceedingly rare in young adults. Differentiated thyroid cancers disproportionately affect women and young adults. Women are five times more likely than men to be diagnosed with thyroid cancer. Medullary thyroid cancer does not show a gender predilection. Papillary thyroid cancer is the most common type of thyroid cancer. It makes up between 70-80 percent of all thyroid cancers. It can occur at any age and it ranges in size and aggressiveness. Follicular thyroid cancer is the second most common type of thyroid cancer, making up 10-15 percent of all thyroid carcinomas. While it can occur in young adults, it usually occurs in patients who are somewhat older than those with papillary thyroid cancer. Medullary thyroid cancer makes up approximately 5 percent of all thyroid cancers. It can occur sporadically but is often familial. There are genetic tests available to check for it. People with a family history of medullary thyroid cancer may be predisposed to other types of cancers and should be screened. Anaplastic thyroid cancer is the rarest form of thyroid cancer. It occurs in less than 5 percent of all thyroid cancer cases. Of those cases 96 percent are diagnosed in individuals over the age of 45. Anaplastic thyroid cancer in the most aggressive form of thyroid cancer and is least likely to respond to treatment. A: Most thyroid cancers are asymptomatic (without symptoms). A nodule (lump or bump) in the thyroid that can be felt is the most common indication of thyroid cancer. The thyroid is a gland located in the neck. Occasionally, thyroid cancer can cause pain, hoarseness, and difficulty swallowing or the patient may experience swollen lymph nodes. Q: What causes thyroid cancer? A: There are many possible causes of thyroid cancer, but most are currently unknown. There is a known association between radiation exposure, especially as a child, and a family history of thyroid cancer. Medullary thyroid cancer and up to 5 percent of papillary thyroid cancers occur in patients with a family history of the disease. However, for the majority of patients the cause is yet to be determined. A: Thyroid nodules can be found with ultrasound but a biopsy is required to diagnose cancer. Usually a fine needle aspiration, guided by ultrasound, is used to get a biopsy. Thyroid scans using a radioactive isotope of iodine (I-131) can be useful in detecting suspicious nodules or distant metastases in differentiated thyroid cancer. The thyroid tissue naturally absorbs iodine to make hormones. Ingesting a small amount of radioactive iodine, then undergoing a scan, can determine how much iodine is absorbed. Nodules that absorb more iodine than surrounding tissue are termed hot, while nodules that absorb less iodine are termed cold. Hot nodules are unlikely to be cancerous, while cold nodules may be malignant or benign. Q: How is thyroid cancer staged? A: Thyroid cancer is staged using the TNM method. T is the tumor size. N is the number of lymph nodes affected. M is the presence of distant metastases. The combination of different levels of T, N and M gives an overall disease stage. Individuals under the age of 45 with differentiated thyroid carcinoma (papillary/follicular) are stage I or II by definition. Those diagnosed with anaplastic thyroid cancer are automatically stage IV to reflect the aggressiveness of their disease. A: Thyroid cancer is first treated with surgery, then followed with radioactive iodine. After surgery patients will be required to start life-long thyroid hormone replacement therapy. Systemic (body-wide) chemotherapy is rarely used to treat thyroid cancer. Q: What kind of surgery will I need? A: The type of surgery required depends upon the type of thyroid cancer, the size or number of tumors, and the involvement of lymph nodes. Most often a total thyroidectomy is done to remove the thyroid. Lymph nodes are often removed to check for regional spread. Low-risk patients sometimes have less extensive surgery. Q: What is recovery from surgery like? What are the risks? A: Recovery from surgery usually takes a few weeks. Patients are typically in the hospital for a few days to a week after surgery. Surgery does carry risks of damage to the laryngeal nerve that may cause hoarseness, or to the parathyroid glands that regulate calcium levels in the blood. However, when surgery is performed by an experienced surgeon, these risks are minimal. Q: What is radioactive iodine ablation? A: The thyroid naturally takes up iodine to make hormones. I-131 is an unstable form of the element iodine (an isotope) that tries to stabilize itself by emitting small amounts of energy in the form of radiation. After a thyroidectomy, radioactive iodine (I-131) is usually used to destroy any remaining thyroid tissue. Radioactive iodine (RAI) is given orally approximately two weeks after surgery. A patient is kept in isolation for a few days after it is administered to prevent him or her from exposing others to the radiation. RAI is useful in differentiated thyroid cancers and plays a role in destroying distant metastases. RAI treatment may temporarily cause decreased saliva production and changes in taste. The lowest effective dose of radiation is always given to minimize side effects. RAI is used in much lower doses in post-treatment thyroid scans to check for disease activity and spread. Before RAI is administered, patients are asked to go off their replacement thyroid hormones for about two weeks to elevate the amount of thyroid stimulating hormone (TSH). TSH promotes the uptake of RAI. When patients are off their thyroid hormones, they may experience symptoms of hypothyroidism, such as fatigue, weight gain or mood change. A synthetic TSH is available, allowing patients to still take thyroid hormones and not experience hypothyroidism. The dose of RAI is much lower for post-treatment scans than for RAI ablation. Q: Why must I follow a low-iodine diet? A: Almost everything we eat contains small amounts of iodine. A low-iodine diet ensures that an optimal amount of RAI is absorbed by the thyroid. Patients follow low-iodine diet for two weeks prior to RAI treatment or a thyroid scan. There are many resources available to help patients develop a low-iodine diet. Examples of foods that need to be avoided include: seafood, dairy products and salt. Q: What about hormone replacement? A: Hormone replacement is necessary after a thyroidectomy. Synthetic hormones are readily available and must be taken for the remainder of a patients’ life. Synthetic thyroid hormones are given at a slightly increased level than normal to suppress TSH. TSH stimulates growth of the thyroid so suppression of TSH is necessary to prevent disease recurrence or spread. Patients will be monitored by an endocrinologist to manage hormone levels. A: Chemotherapy is rarely used to treat thyroid cancer. Because of the high rates of cure using surgery and RAI alone, it is often not necessary. However, it may be used if the disease is recurrent or very aggressive and other methods have been exhausted. Chemotherapy is more commonly used in older patients. Q: What kind of follow up will I need? A: According to NCCN Clinical Practice Guidelines, a physical examination and a blood test to check thyroglobulin, TSH and antithyroglobulin antibodies levels are recommended at 6 and 12 months after initial treatment, then annually if disease free. Periodic neck ultrasounds may be necessary. Radioactive iodine scans are recommended only in patients with a TNM stage of T3-T4 or M1, or if there is an abnormal blood test result. These tests may be performed using synthetic TSH except in high-risk cases when going hypothyroid is recommended for a period before the scan. A: Thyroid cancer recurs in approximately 15-35 percent of cases. Recurrence can occur up to decades after initial treatment. It most often recurs in the lymph nodes in the neck. Regular follow-up by your doctor with a physical exam is the best way to check for recurrence. Rarely, thyroid cancer can metastasize to the lungs or bones. A: The prognosis for young adults diagnosed with thyroid cancer is excellent. The overall survival rate in patients with local or loco-regional disease is 97-100 percent. According to SEER data, those diagnosed in the 15-29 age group have a greater than 99 percent chance of five-year survival. Q: What about thyroid cancer and pregnancy? A: Thyroid cancer is the second most common cancer diagnosed during pregnancy, after breast cancer. Surgery can usually be postponed until the mother has given birth. If surgery is necessary sooner, it may be performed in the second trimester. RAI is not given during pregnancy or while breastfeeding. Women have an increased need for thyroid hormones during pregnancy. Synthetic thyroid hormones may be given to suppress TSH levels and to stop disease progression. Q: Can radioactive iodine (RAI) affect fertility? A: In men RAI can temporarily decrease sperm count and affect fertility. The dosage of radiation affects the degree to which sperm count decreases. The American Thyroid Association recommends sperm banking before high-dose RAI treatment. While radiation does temporarily affect the menstrual cycle there is no increased risk of infertility, miscarriage or congenital defects. It is recommended, however, that women wait six-12 months before trying to get pregnant to ensure that the disease is not recurrent. RAI should not be given to women who are breastfeeding. Q: What are the long-term/late effects of thyroid cancer? A: Those who have been treated for thyroid cancer usually have good outcomes and high quality of life. Surgery will leave a scar (the degree varies by individual) and it can be associated with voice problems and hypoparathyroidism (problems regulating blood calcium levels). RAI can have permanent effects on salivary glands and taste. Eating sour sweets such as lemon drops may minimize the effects of radiation on the salivary glands. Patients who have had radiation may be at risk for parotid cancer (cancer of the salivary gland.) There may be risks to the heart and bones from TSH suppression although the link is unclear. It is not unusual for those who have been treated for thyroid cancer to experience fatigue, psychological issues, and memory and concentration problems. Q: Where can I find more resources and information? A:There are many resources for those who have been diagnosed with thyroid cancer. The Internet is a good place to start. Recommended sites include:
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