Thyroid cancer that has returned after treatment is called recurrent disease. Most cases of recurrent thyroid cancer occur in the neck region, but some also have distant metastases, or cancer that has spread to distant locations in the body. The most common site of distant metastasis is the lung.
About this Treatment Information
The following is a general overview of treatment for recurrent thyroid cancer. Cancer treatment may consist of radioactive iodine treatment, surgery, radiation, chemotherapy, or a combination of these treatment techniques. Combining two or more of these treatment techniques has become an important approach for increasing a patient’s chance of cure and prolonging survival.
In some cases, participation in a clinical trial utilizing new, innovative therapies may provide the most promising treatment. Treatments that may be available through clinical trials are discussed in the section titled Strategies to Improve Treatment.
Circumstances unique to each patient’s situation influence which treatment or treatments are utilized. The potential benefits of multi-modality care, participation in a clinical trial, or standard treatment must be carefully balanced with the potential risks. The information on this website is intended to help educate patients about their treatment options and to facilitate a mutual or shared decision-making process with their treating cancer physician.
Treatment for Recurrent Thyroid Cancer
Treatment for recurrent thyroid cancer depends on many factors, including prior treatment, the cell type that is now cancerous, whether the cells will respond to radioactive iodine treatment, site of recurrence, and other individual considerations.
Surgery is often a key component of treatment for recurrent thyroid cancer, followed by repeated radioiodine treatments.
However, some patients with recurrent disease are resistant to radioactive iodine treatment, meaning their thyroid cells do not take up the iodine. Treatments are more limited for these patients, and they may benefit from participating in a clinical trial evaluating new, innovative approaches to treating thyroid cancer.
If patients with recurrent thyroid cancer have not already had their thyroid removed, they will likely undergo a total thyroidectomy to remove the rest of their thyroid and any other cancer in the neck region. Patients who have had their thyroid removed also often have recurrent cancer in the neck region and will undergo surgery to have as much of the cancer as possible removed.
Radioactive Iodine Treatment
Iodine is a natural substance that the thyroid uses to make thyroid hormone. The radioactive form of iodine is collected by the thyroid gland in the same way as non-radioactive iodine. Since the thyroid gland is the only area of the body that uses iodine, the radiation does not concentrate in any other areas of the body. The radioactive iodine that is not taken up by thyroid cells is eliminated from the body, primarily in urine. It is therefore a safe and effective way to test and treat thyroid conditions.
Research indicates that treatment with radioactive iodine improves survival for patients with thyroid cancer that has spread to nearby lymph nodes or to distant locations in the body. 
Strategies to Improve Treatment of Thyroid Cancer
The development of more effective cancer treatments requires that new and innovative therapies be evaluated with cancer patients. Clinical trials are studies that evaluate the effectiveness of new drugs or treatment strategies. Future progress in the treatment of recurrent thyroid cancer will result from the continued evaluation of new treatments in clinical trials.
Patients may gain access to better treatments by participating in a clinical trial. Participation in a clinical trial also contributes to the cancer community’s understanding of optimal cancer care and may lead to better standard treatments. Patients who are interested in participating in a clinical trial should discuss the risks and benefits of clinical trials with their physician. Areas of active investigation aimed at improving the treatment of recurrent thyroid cancer include the following:
Surgery to remove metastases: Surgery to remove metastases from thyroid cancer has been shown to benefit some patients. In a clinical trial, metastases from thyroid cancer were removed from the mediastinum (area behind the breast bone), lung, bone, kidneys, and brain of 29 patients with advanced thyroid cancer. All patients were also treated with multiple radioiodine treatments. External-beam radiation therapy, chemotherapy, and other measures to relieve symptoms of the cancer were used. 
Chemotherapy: Chemotherapy uses drugs that kill rapidly dividing cells, a hallmark of cancer. Cancer chemotherapy may consist of single drugs or combinations of drugs. It can be administered through a vein, injected into a body cavity, or delivered orally in the form of a pill. Chemotherapy is different from surgery or radiation therapy in that the cancer-fighting drugs circulate in the blood to parts of the body where the cancer may have spread and can kill or eliminate cancers cells at sites great distances from the original cancer. As a result, chemotherapy is considered a systemic treatment.
Doctors have observed that chemotherapy may help relieve symptoms of advanced thyroid cancer and may increase survival of some patients. 
Intensity-modulated radiation therapy (IMRT): IMRT allows radiation to be delivered more precisely with the use of the following advanced techniques:
- Three-dimensional scans of the cancer help determine where the radiation should be targeted.
- A rotating device delivers radiation from every point around the cancer, rather than only a few points as with conventional radiation therapy.
- Special blocking devices—called leaves—direct the radiation away from sensitive organs and toward the cancer.
IMRT appears to reduce the chance of injury to healthy body structures that are near the cancer while delivering higher doses of radiation to the cancer. In the treatment of thyroid cancer, this means that sensitive cells in the neck area—such as the cells that line the throat—may be spared from radiation damage, reducing side effects and improving quality of life.
Preliminary findings reported by researchers in New York suggest that IMRT is an effective treatment for select cases of thyroid cancer. However, long-term research is needed to confirm these findings. IMRT may be available through a clinical trial.
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