Radiation Therapy For Thyroid Cancers
Doctors at NYU Langone may prescribe radiation therapyin which energy beams are used to destroy cancer cellsin people with advanced thyroid cancer that does not respond to radioactive iodine therapy.
NYU Langone doctors may use external beam radiation therapy, which uses a machine called a linear accelerator. External beam radiation therapy is typically given after surgery for thyroid cancers that do not absorb radioactive iodine, including many forms of cancer that have spread.
External beam radiation therapy can help destroy any remaining thyroid cancer cells, including those that have spread to lymph nodes in the neck or other parts of the body, such as the lungs or liver. This form of radiation may also be used to treat these forms of thyroid cancer in people who cannot have surgery due to poor health.
Preparing For Radioactive Iodine Treatment For Thyroid Cancer
Radioactive iodine treatment is a type of internal radiotherapy. It uses a radioactive form of iodine called iodine 131 . It is a useful treatment in thyroid cancer because the thyroid gland absorbs and stores most of the iodine in your body. The thyroid gland gets iodine from certain foods and uses this to make essential thyroid hormones.
Radioactive iodine is a targeted treatment. The radioactive iodine circulates throughout your body in your bloodstream. But it is mainly taken up by thyroid cells, having little effect on other cells. Thyroid cancer cells in your body pick up the iodine. The radiation in the iodine then kills the cancer cells.
It is only suitable for some types of thyroid cancer. It is a treatment for:
- follicular thyroid cancer
- papillary thyroid cancer
It can treat the cancer even if it has spread. But even if you have one of these types of thyroid cancer, this treatment may not be necessary or suitable for you. Not all of the cancer cells take up the iodine so you may have a test dose to see if they do.
Are There Permanent Side Effects From Radioactive Iodine Therapy
It is highly likely that this procedure will destroy some or most of your thyroid gland. Since hormones produced by the thyroid are essential for metabolism, most patients will need to take thyroid pills for the rest of their life following the procedure. Thyroid pills are inexpensive, and patients will typically be prescribed one pill per day. There are essentially no other permanent side effects from the procedure. The risk of cancer from this therapy is very small.
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Radioactive Iodine As A Diagnostic Tool
Radioactive Iodine Scanning is a diagnostic test in which a small tracer dose of radioactive iodine is given by mouth. The drug is taken up by the thyroid which then emits a small amount of radioactivity that can be detected by a geiger counter to create an image. This test identifies the size and location of the thyroid gland. It can also be used to identify sites of thyroid cancer that have spread beyond the thyroid itself. The test is commonly used to evaluate the function of the thyroid and can help in the evaluation and diagnosis of patients with subacute thyroiditis, Graves disease and toxic nodular goiters. In the past, radioactive iodine scanning was used to evaluate thyroid nodules. Cold nodules were associated with tumors, while hot nodules indicated a focus of thyroid tissue that was overproducing thyroid hormone. Radioactive iodine scanning is still helpful in the workup of patients with hyperthyroidism, but the evaluation of most thyroid nodules today is better done with fine needle aspiration.
Discuss Your Treatment Plan
Your doctor will discuss your treatment plan with you.
Your treatment plan will follow these steps that will take place over a few days:
1. On the first day, youll have blood tests. After those tests, youll see your doctor and get a thyrotropin alfa injection to help you get ready for your treatment. This injection will help any leftover thyroid tissue absorb the radioactive iodine.
2. On the second day, youll get another thyrotropin alfa injection. Then youll get a small diagnostic dose of radioactive iodine in a pill. You wont have to follow any precautions after getting this small diagnostic dose of radioactive iodine. After you take this pill, youll have a whole-body scan. This scan will show your doctor how the radioactive iodine is being taken up in your body.
3. On the third day, youll have your full dose of radioactive iodine treatment. This is an outpatient procedure, so you wont be admitted to the hospital.
4. Youll have another whole-body scan several days after your treatment. This helps your doctor see where the dose of radioactive iodine was taken up in your body.
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What Is Radioiodine Ablation
Radioactive iodine therapy can destroy either all or part of your thyroid gland, depending on what is needed to alleviate your . In some cases, it is not necessary to have the entire thyroid gland rendered nonfunctional. In most cases, though, the whole gland will need to be destroyed.
Your doctor may refer to radioactive iodine therapy as radioactive iodine ablation or radioiodine ablation. Ablation is a term that refers to destruction or erosion.
Here is what you might expect when undergoing radioactive iodine therapy, starting with how your doctor will determine what dose will be necessary to treat your particular case of hyperthyroidism.
The Actual Radioiodine Treatment
When giving RAI for cancer, there are two parts to treatment.
- Preparing your body for RAI. You will need to a. Go on a low-iodine diet, and b. Increase the level of TSH in your blood . This can be achieved in two ways:
- Go off thyroid replacement and become hypothyroid
- Temporarily raise the TSH by artificially stimulating the the TSH levels to increase. This is done by giving a medication called Thyrogen for two days before I131
Radiation safety
- Sometimes this will require hospitalization for up to 24 hours
- Contact precautions for a few days
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What Is Radioiodine Therapy And How Is It Used
Radioactive Iodine I-131 therapy is a nuclear medicine treatment. Doctors use it to treat an overactive thyroid, a condition called hyperthyroidism. Hyperthyroidism can be caused by Graves’ disease, in which the entire thyroid gland is overactive, or by nodules within the gland which are locally overactive in producing too much thyroid hormone.
Nuclear medicine uses small amounts of radioactive material called radiotracers. Doctors use nuclear medicine to diagnose, evaluate, and treat various diseases. These include cancer, heart disease, gastrointestinal, endocrine, or neurological disorders, and other conditions. Nuclear medicine exams pinpoint molecular activity. This gives them the potential to find disease in its earliest stages. They can also show whether you are responding to treatment.
The thyroid is a gland in the neck that produces two hormones. These hormones regulate all aspects of the body’s metabolism, the chemical process of converting food into energy. When a thyroid gland is overactive, it produces too much of these hormones, accelerating the metabolism.
Radioactive iodine , an isotope of iodine that emits radiation, is used for medical purposes. When a small dose of I-131 is swallowed, it is absorbed into the bloodstream in the gastrointestinal tract. It is concentrated from the blood by the thyroid gland, where it begins destroying the gland’s cells.
Doctors also use radioactive iodine I-131 to treat thyroid cancer.
Papillary Cancer And Its Variants
Most cancers are treated with removal of the thyroid gland , although small tumors that have not spread outside the thyroid gland may be treated by just removing the side of the thyroid containing the tumor . If lymph nodes are enlarged or show signs of cancer spread, they will be removed as well.
In addition, recent studies have suggested that people with micro-papillary cancers may safely choose to be watched closely with routine ultrasounds rather than have immediate surgery.
Even if the lymph nodes arent enlarged, some doctors recommend central compartment neck dissection along with removal of the thyroid. Although this operation has not been shown to improve cancer survival, it might lower the risk of cancer coming back in the neck area. Because removing the lymph nodes allows them to be checked for cancer, this surgery also makes it easier to accurately stage the cancer. If cancer has spread to other neck lymph nodes, a modified radical neck dissection is often done.
Treatment after surgery depends on the stage of the cancer:
People who have had a thyroidectomy will need to take daily thyroid hormone pills. If RAI treatment is planned, the start of thyroid hormone therapy may be delayed until the treatment is finished .
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Maximizing The Effectiveness Of Radioactive Iodine Therapy
Radioactive iodine therapy for thyroid cancer is most effective in people who have high levels of thyroid-stimulating hormone, or TSH. This hormone is produced by the pituitary gland, which is located at the base of the brain and produces many hormones. TSH tells the thyroid to absorb iodine, which is then converted to thyroxine. The thyroids ability to absorb iodine is important for the success of radioactive iodine therapy.
If youve had surgery to remove part or all of the thyroid, your doctor may wait a few weeks before prescribing a replacement thyroid hormone. During that time, you experience whats known as thyroid hormone withdrawal, which makes the pituitary excrete more TSH. Excess thyroid-stimulating hormone is necessary for the success of radioactive iodine therapy.
Another way your doctor may try to increase the effectiveness of radioactive iodine therapy is to give you an injection of a medication called recombinant human thyroid hormonethyroid-stimulating hormone made in a laboratory. This injection is given for two days before radioactive iodine therapy begins. The medication elevates thyroid-stimulating hormone levels enough to make the radioactive iodine therapy as effective as thyroid hormone withdrawal.
When radioactive iodine therapy is being considered for thyroid cancer, the body must be depleted of inorganic iodine, so the levels of thyroid-stimulating hormone increase, helping with the effectiveness of radioactive iodine therapy.
When Is Rai Used For Treatment Of Thyroid Disorders
THYROID TISSUE I-131 is given to destroy overactive thyroid tissue or to shrink thyroid glands that are functioning normally but are causing problems because of their size . Patients are asked to follow some radiation precautions after treatment in order to limit radiation exposure to others . I-131 may occasionally cause mild pain in the neck that can be treated with aspirin, ibuprofen or acetaminophen. The RAI treatment may take up to several months to have its effect. Frequently, the end result of RAI treatment of hyperthyroidism is hypothyroidism, which is treated by thyroid hormone replacement .
THYROID CANCER Large doses of I-131 are used to destroy thyroid cancer cells . This is performed after the remaining thyroid cells are stimulated by raising TSH levels by either withdrawing the thyroid hormone pills or by treating with recombinant human TSH. Patients are asked to follow some radiation precautions after treatment in order to limit radiation exposure to others . Depending on state regulations, patients may have to stay isolated in the hospital for about 24 hours to avoid exposing other people to radiation, especially if there are young children living in the same home.
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Radioactive Iodine Therapy: Indications
RAI therapy has been approved for therapeutic use on both benign and malignant thyroid conditions. For instance, it is indicated for the management of overactive thyroid tissue and some types of thyroid cancer. Also, this therapy can be used to decrease the size of glands that are not hyperfunctioning but are causing signs or symptoms due to their size. Concrete indications for RAI therapy are:1
- Graves disease
Toxic nodular goiter
The goal of treatment in multinodular goiter and toxic adenoma is the rapid and long-lasting resolution of hyperthyroidism. Along with surgery, RAI therapy is one of the definitive treatments for this condition. It can decrease the size of the nodules, thereby reducing the signs and symptoms of hyperthyroidism.2 A single dose has been shown to reduce goiter size by up to 40% and it usually succeeds in 85-100% of patients with toxic nodular goiter.2
In these conditions, possible indications for RAI therapy include advanced age, small goiter size, significant coexistent diseases, and prior surgery or scarring of the anterior neck.3
Thyroid cancer
Large doses of RAI may also be useful to treat certain types of thyroid cancer. It is usually helpful for patients with papillary and follicular carcinomas. However, it is of no use in cases of medullary thyroid carcinoma and anaplastic carcinoma because these tumors dont take up radioactive iodine.4
Non-Toxic Multinodular Goiter
What Is Radioactive Iodine Therapy
Radioactive iodine can be used for the treatment of overactive thyroid and certain types of thyroid cancer. The term radioactive may sound frightening, but it is a safe, generally well-tolerated, and reliable treatment that targets thyroid cells so there is little exposure to the rest of your bodys cells.
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A Special Caution For Pregnant Or Breastfeeding Women
Pregnant women or women who want to become pregnant in the next 6 months should not use radioactive iodine, as the treatment can destroy the fetuss thyroid and impair its development. Women who are breastfeeding should also not have radioactive iodine therapy.
Additionally, if you have been treated with radioactive iodine therapy you should wait a year after the treatment before conceiving, to ensure the radiation has adequately cleared your body.
What Does Going Hypo Mean
Our bodies require thyroid hormone to function normally. This is why people need to take a synthetic form of the hormone, by pill, once the thyroid has been removed. Synthroid® and Eltroxin® are brands of thyroid pills in Canada.
Without thyroid hormone, the body produces more and more thyroid stimulating hormone . A high level of TSH is needed for RAI treatment to be effective. This is why your doctor may instruct you to stop taking your thyroid pills 4-6 weeks before starting RAI treatment. Temporarily stopping your thyroid pills may cause symptoms of hypothyroidism . Symptoms tend to be more common in the 2 weeks leading up to your RAI treatment.
They include:
- Puffiness in the face bloating
- Poor concentration
Your doctor may prescribe a drug called Cytomel® to help ease these symptoms of hypothyroidism.
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D Recombinant Human Tsh
Within 1 yr after 131I therapy, the volume reduction of a nodular goiter is approximately 4045%, but with pronounced interindividual variation . The effect in diffuse nontoxic goiters is even more pronounced . Despite sufficient volume reduction, a high degree of patient satisfaction, and relief of the cervical compression and cosmetic complaints, many patients with goiter are referred to thyroidectomy rather than 131I therapy. It should be noted, however, that vocal symptoms and a decrease in swallowing performance are frequent occurrences even late after total thyroidectomy, despite the absence of immediate operative complications . Particularly elderly patients are at risk of having surgical complications . No trial has compared the two treatments head to head, and the choice of observation, surgery, or 131I therapy must be based on a range of individual factors in a dialogue with the patient.
1 Evolution of rhTSH
2 Application in thyroid cancer patients
3 Impact on the thyroid RAIU
The positive effect of rhTSH stimulation on the thyroid 131I uptake in patients with MNG is clearly inversely related to the initial 131I uptake. With a high thyroid 131I uptake, very little is gained by rhTSH stimulation.
4 Application in patients with benign goiter
5 Potential concerns with rhTSH-stimulated 131I therapy
6 Extrathyroidal effects of rhTSH
What Is A Thyroid Nodule
Thyroid nodules can be caused by various elements and can also be formed from different biological materials. The definition of a thyroid nodule is broad and is simply a lump in the thyroid gland in your neck.
These lumps can be solid, fluid-filled, or a mix of both. Although most people think of cancer whenever they hear the word ‘lump,’ thyroid nodules are almost always non-cancerous.¹
However, you should always see a doctor any time you notice a lump.
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Thyroid Medicine After Radioactive Iodine Treatment
You may have stopped taking your thyroid hormone tablets in preparation for your treatment. Your nurse will tell you when you should start to take them again. Usually, this is 2 to 3 days after your treatment.
You will need to take thyroxine tablets to replace the hormones that your thyroid gland normally makes. Your doctors will want to keep your thyroid hormones at a slightly higher level than you would normally need. This is to stop your body producing another hormone called thyroid stimulating hormone . TSH can help some types of thyroid cancer cells to grow.
The doctors will work out the correct dose for you and when to start taking it.
Why It Is Done
Radioactive iodine may be used to treat hyperthyroidism in people who have noncancerous thyroid nodules that make too much thyroid hormone.
Radioactive iodine is also used if you have your thyroid removed because of thyroid cancer. Radioactive iodine therapy destroys any remaining thyroid tissue or cancer cells that were not removed during surgery.
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Does Rai For Thyroid Imaging Provide The Best Results
I-123 is the usual isotope used to take pictures and determine the activity of the intact thyroid gland , since it is harmless to thyroid cells. No special radiation precautions are necessary after a thyroid scan or RAIU using I-123. I-131 can also be used to take pictures of the thyroid gland, although it is rarely used due to the harmful effects it has on thyroid cells.