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Treatment and Follow-Up

Treatment Overview

• Treatment for differentiated pediatric thyroid cancer usually begins with a thyroidectomy ( removal of both lobes and isthmus of the thyroid gland).
  Prior to surgery, the American Thyroid Association (ATA) and European Thyroid Association (ETA) Guidelines for the management of thyroid cancer advise preoperative neck ultrasonography, both in adults and children, to carefully inspect the lymph node compartments in the lateral and central neck for metastases.

  In addition, at surgery the surgeon normally inspects the neck for enlarged lymph nodes, but ultrasonography is more likely to identify small malignant lymph nodes than is feeling the neck during surgery.

• Clinical trials of new medications are also in progress to seek better treatments for patients whose differentiated thyroid cancer has spread and continues to grow despite standard therapy.
  

Surgery

• Treatment for differentiated pediatric thyroid cancer usually begins with a a total or nearly total thyroidectomy ( removal of both lobes and isthmus of the thyroid gland).

  Prior to surgery, the American Thyroid Association (ATA) and European Thyroid Association (ETA) Guidelines for the management of thyroid cancer advise preoperative neck ultrasonography, both in adults and children, to carefully inspect the lymph node compartments in the lateral and central neck for metastases.

  In addition, at surgery the surgeon normally inspects the neck for enlarged lymph nodes, but ultrasonography is more likely to identify small malignant lymph nodes than is feeling the neck during surgery.

• The surgeon may alter the extent of the initial surgery, depending on the size of the thyroid tumor and whether or not there is evidence of lymph node metastases and/or tumor invading the thin capsule of the thyroid into surrounding neck tissues. Tumor that is outside the confines of the thyroid gland, and that is invading the soft tissues of the neck, can usually be removed without injury to the neck muscles or recurrent laryngeal nerve needed by the vocal cords.

  Abnormal-appearing or biopsy-proven metastatic lymph nodes are excised during surgery. In the past, only selected lymph nodes thought to be involved with tumor were removed, a procedure called selective lymph node dissection. However, now both the ATA and ETA guidelines suggest total removal of entire groups of lymph nodes within one or another neck compartment only if at least one malignant lymph node is found.

  Some surgeons prophylactically remove all the lymph nodes in the central neck when the patient has a very aggressive tumor, whether or not any are known to be malignant at the time of surgery. In most cases, however, this is not done in children with differentiated thyroid cancer without a clear diagnosis of metastatic tumor in at least one lymph node. In adults, the ATA but not the ETA advise prophylactic lymph node dissection of the central neck lymph node compartments.

• Risks related to surgery are greatest among patients under the age of 4. Children over the age of 10 have significantly better outcomes.

• The best outcomes are achieved when surgery is performed by an experienced thyroid surgeon, so parents of children with thyroid cancer are encouraged to seek out regional or national specialists in this area who have performed many similar surgeries.

• The risks of surgery include:

  • Laryngeal nerve damage, resulting in a change in the voice quality. This is usually temporary, but in rare cases is permanent. A number of corrective measures are possible.
• Low calcium levels in the blood due to damage to the parathyroid glands. This results in hypoparathyroidism and the need for calcium and vitamin D supplementation, often only for a period of 2 to 4 weeks. However, surgery can also result in lifelong hypoparathyroidism.
• Infection. This is a very rare complication. It is treated with antibiotics.
• Bleeding. This is rare and is controlled at the time of the operation or afterward.

Radioactive Iodine (RAI): Radioactive Iodine 131 Therapeutic Ablation

• Normal thyroid tissue takes iodine from the blood stream and traps it within the cell to make thyroid hormone. Differentiated thyroid cancers also retain some of this ability. This is the rationale for using radioactive forms of iodine (RAI) in the treatment of papillary and follicular thyroid cancer.
• The goal of using RAI is three-fold:
  • to destroy any remaining normal thyroid tissue (this process is also known as thyroid remnant ablation), to facilitate long-term monitoring for residual or recurrent thyroid carcinoma through the use of thyroglobulin testing (see below) and RAI scans;
  • to destroy any residual thyroid cancer cells that may remain in or near the remaining normal thyroid tissue; and
  • to destroy metastatic disease that concentrates RAI in lymph nodes and elsewhere, such as the lungs.
• The dose of radioactive iodine is individually tailored to meet the needs of each child.
• Dosimetry to calculate the dose of RAI may be used in some institutions, while other institutions base the dose on the child's weight and the extent of disease.
• RAI is given several weeks after surgery.
• A thyroid scan (called a diagnostic thyroid scan) is often obtained prior to treatment with high-dose RAI to assess the extent of disease. However, neither the ATA or ETA guidelines recommend this test in most cases because it may impair uptake of RAI (I 131) by malignant thyroid or small remnants of normal thyroid tissue. A large study of 800 patients given RAI (I 131) after surgery found that 96% of the time the diagnostic scan showed evidence of tumor or a large remnant of normal thyroid tissue.
• A post-ablation thyroid scan (also known as a post-therapy scan) is obtained a few days to a week after the radioactive iodine. This scan is done to assess for additional sites of RAI uptake that may not have been obvious on the diagnostic scan.
• Ablation means the elimination of the thyroid tissue remaining in the neck area after the surgery, as well as any microscopic traces of thyroid cancer that may be elsewhere in the body. The radioactive iodine ablation is done to kill any remaining thyroid tissue in the thyroid bed area and any microscopic traces of thyroid cancer that remain in the body.
• In children, the dose of radioactive iodine varies according to the age and weight of the patient and the extent of tumor.
• The amount of radioactive iodine given is tailored to meet the needs of treating each child's cancer involvement.
• Another purpose of radioiodine is to ensure that follow-up measurements of Thyroglobulin are more useful. Thyroglobulin (Tg) is a blood test that is a marker of the presence of both normal and abnormal thyroid cells. If normal thyroid tissue remains after surgery, thyroglobulin monitoring is not as sensitive in determining who is and who isn’t cured from their thyroid cancer.
• For more information about radioactive iodine, and the procedures to follow after receiving it, visit the Radiation: RAI section of the ThyCa web site. http://www.thyca.org/rai.htm
• For more information about Thyroglobulin testing, read the Thyroglobulin Texting article at: http://www.thyca.org/thyroglobulin.htm/

Low-Iodine Diet

• In preparation for receiving radioactive iodine, patients are usually asked to go on a low-iodine diet (LID).
• The purpose of a low-iodine diet is to deplete the body of its stores of iodine, to help increase the effectiveness of the radioactive iodine scan or treatment.
• This diet is for a short time period. The usual time period is around two weeks (14 days) or slightly more. The diet usually begins around two weeks before testing and continues through the testing and treatment period. However, recommendations for the time period can vary, depending partly on the individual patient's circumstances.
• For the guidelines and tips, visit this page on ThyCa's web site: http://www.thyca.org/rai.htm#diet
• Free Downloadable Low-Iodine Cookbook: The free Low-Iodine Cookbook gives the guidelines and tips for the low-iodine diet. It also has a one-page summary of the guidelines, plus tips for meals and snacks. You will also more than 185 delicious recipes contributed by thyroid cancer survivors as their family favorites.
  http://www.thyca.org/Cookbook.pdf
• Low-Iodine Diet for Kids: Meals, Snacks, Recipes, and Tips

Thyroid Stimulating Hormone (TSH) Suppression

• Patients treated for differentiated thyroid cancer take a daily thyroid hormone replacement pill called levothyroxine (also known as T4). They take it both to avoid hypothyroidism (underactive thyroid condition) and to prevent growth or recurrence of their thyroid cancer.
• Usually they receive a T4 dose large enough to suppress their blood level of thyroid stimulating hormone (TSH) below the normal TSH range. This is called TSH suppression. The ATA and ETA guidelines suggest TSH suppression when a patient has active tumor or has a very aggressive tumor that has been treated with surgery and radioactive iodine (I 131). However, about 85% of patients can be shown to be free of disease after initial tumor treatment by testing the patient' serum thyroglobulin levels and performing neck ultrasonography. When the patient is felt to be free of tumor on this basis, the ATA and ETA guidelines suggest maintaining the blood TSH in the low normal level, which is particularly important in children.
• Patients whose thyroid glands have been removed will need to be on levothyroxine medication for the rest of their lives. The medication, which is necessary for maintaining a person's full health, must be taken on an empty stomach. Generally, it should not be taken with other drugs, since a large number of drugs interfere with thyroid hormone getting into the blood stream. Drugs as common as vitamins with iron can do this. It is necessary to check with the pharmacist and physician when new drugs are being prescribed
• There are several brands of levothyroxine. Thyroid cancer specialist physicians recommend that patients stay on the same brand and not change unless a re-test of their blood is done 6 weeks later, because the brands may not result in the same TSH level, even at the same dose.
• More information about levothyroxine is in the web site section titled "Know Your Pills." http://www.thyca.org/knowpills.htm

Follow-Up Testing

• Thyroid cancer patients undergo periodic monitoring for the rest of their lives.
• The type of testing and how often it takes place depend on the size of the tumor, whether there was spread, and other factors.
• Patients who are free of disease receive less monitoring than those with evidence of disease.
• The testing is spread out over time, at less frequent intervals, when the patient becomes free of disease.
• However, even those patients cured of their thyroid cancer need to see a doctor at least once a year for measurement of thyroglobulin and thyroid function tests.

Testing may include:

• Thyroid scan (radioactive iodine whole-body scan) either after thyroid hormone withdrawal or after administration of recombinant TSH (Thyrogen).
• Neck Ultrasound. This test is increasingly used, because it is a very sensitive way to find disease in the neck.
• Blood testing for TSH (thyroid stimulating hormone). Often, this is done about every 3 to 6 months during the first few years after diagnosis and less frequently later on.
• The frequency of thyroid function testing (TSH testing) also depends on the age of the patient. Younger children typically require more frequent monitoring for longer periods of time.
• Blood testing for Thyroglobulin (Tg).
  • This is another important test, because thyroglobulin is made only by thyroid cells, normal and cancerous.
  • Often, Tg measurements are done every time the TSH is checked, although, with more time from diagnosis and with no evidence of disease, the frequency of Tg monitoring becomes less frequent, usually only once a year.
  • About one quarter of patients make an antibody against thyroglobulin (antithyroglobulin antibody) that prevents interpretation of the actual Tg level. In effect, the presence of thyroglobulin antibodies will usually cause the Tg level to read artificially low. In these cases, the antibodies levels themselves can be monitored and should become undetectable, in most patients with no evidence of disease, by 3-5 years after diagnosis.
  • The web site has an article with more information about Thyroglobulin measurement and the different tests used. http://www.thyca.org/thyroglobulin.htm
• Physical Examination. Typically, this is done every 3 to 6 months for the first 2 years and then once a year if there is no recurrence of the thyroid cancer.
• Other tests sometimes used:
  • Chest X-Ray
  • CT scan with or without contrast. The CT should be without contrast if the use of radioactive iodine is planned shortly thereafter. Otherwise, a 24-hour urine collection for iodine may be collected prior to any use of RAI to ensure that the iodine load from the CT contrast has been cleared.
  • PET scans for those with persistent elevations of thyroglobulin and no evidence of disease on ultrasound, RAI scan, and other imaging methods.

Last updated: February 21, 2007