Thyroid Cancer Treatment: Surgery, Radioactive Iodine, and Other Options Explained

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Last updated and reviewed on: September 11, 2026

If you or someone you love just learned about a thyroid cancer diagnosis, one of the first questions is usually simple: what happens next? Thyroid cancer treatment looks different for different people. Your care team will build a plan around your specific tumor type, its size, whether it has spread, and your own health and preferences. This guide walks through the main treatment options in plain language, so you can understand what your doctor is recommending and why.

One thing to understand right away: thyroid cancer is not one single disease.

Papillary thyroid carcinoma and follicular thyroid carcinoma, together called differentiated thyroid cancer (DTC), make up the large majority of cases and are usually treated with surgery, sometimes followed by radioactive iodine.
Medullary thyroid carcinoma (MTC) is a different disease that starts in different cells and is treated differently in several important ways.
Anaplastic thyroid carcinoma (ATC) is rare, grows quickly, and requires urgent, specialized care. This guide covers all three, and it will always tell you which type it is talking about so you are never left guessing whether a section applies to you.

How Is Thyroid Cancer Treated?

Most people with thyroid cancer are treated with some combination of six main approaches: surgery, radioactive iodine (RAI) therapy, thyroid hormone therapy, external beam radiation, targeted therapy or chemotherapy, and, for a small group of very low-risk patients, active surveillance (closely watching a small cancer instead of treating it right away). Surgery is the starting point for almost everyone who needs treatment. From there, the plan branches depending on the type of thyroid cancer, how far it has spread, and features seen under the microscope.

For differentiated thyroid cancer, which includes papillary thyroid carcinoma (the most common type) and follicular thyroid carcinoma, treatment usually means surgery, often followed by radioactive iodine for people with higher-risk features, and then lifelong thyroid hormone therapy. Because papillary and follicular cancers tend to grow slowly and respond well to treatment, some people with a very small, low-risk papillary tumor may be offered active surveillance instead of immediate surgery. This means your doctor monitors the tumor closely with ultrasound and only recommends surgery if it grows or changes. This is a real option discussed with your care team based on your specific staging, not something you should try to decide on your own.

Medullary thyroid cancer works differently. It starts in C cells (thyroid cells that make a hormone called calcitonin), not the follicular cells that give rise to papillary and follicular cancer. Because of this, MTC does not respond to radioactive iodine, and thyroid hormone suppression is not used the same way. Surgery, and in more advanced cases, targeted drugs, play a bigger role. Genetic testing for RET gene changes (alterations in a gene called RET that can drive thyroid cell growth) is also a standard part of care for anyone diagnosed with MTC, since roughly one quarter of cases are inherited.

Anaplastic thyroid cancer is different again, and much more serious. It is rare, but it grows very fast and is treated as a medical emergency. Care usually starts within days of diagnosis and combines several treatments at once, including surgery when possible, external radiation, and targeted therapy or chemotherapy.

We cover ATC in its own section below because the approach, the pace, and the goals of treatment are so different from DTC and MTC.

Even though differentiated thyroid cancer is often described as having a good prognosis, that does not make your diagnosis less real. Surgery, radioactive iodine, a lifetime of daily medication, and the fear of recurrence are genuine burdens, even when the long-term outlook is favorable. You are allowed to feel the weight of a cancer diagnosis while also holding on to good reason for hope.

Surgery for Thyroid Cancer

Surgery is the first treatment for nearly every person with thyroid cancer, regardless of type. The two main operations are a lobectomy, which removes only half of the thyroid gland (called a lobe) that contains the tumor, and a total thyroidectomy, which removes the entire gland. Your surgeon chooses between them based on the size of the tumor, whether it appears to be confined to one lobe, whether it has spread to lymph nodes, and other risk features found on imaging or biopsy before surgery.

Generally, a lobectomy may be an option for a small, low-risk papillary or follicular cancer that has not spread beyond the thyroid. An advantage of a lobectomy is that you might not need lifelong thyroid hormone replacement afterward, since part of your thyroid remains. A total thyroidectomy is usually recommended for larger tumors, cancers in both lobes, cancers with higher risk features, or medullary and anaplastic thyroid cancer. After a total thyroidectomy, your body can no longer make its own thyroid hormone, so you will need to take a daily hormone pill for the rest of your life, a topic covered in detail in the next section.

If imaging or biopsy shows the cancer has spread to lymph nodes in the neck, your surgeon may also remove those nodes at the same time as the thyroid, or sometimes in a second operation. Removing lymph nodes from the area right around the thyroid is called a central neck dissection. If cancer is found in lymph nodes farther out along the side of the neck, that is called a lateral neck dissection. Not everyone needs a lymph node dissection. Your surgical team decides based on what imaging and, when needed, biopsy show before or during surgery.

Recovery from thyroid surgery is usually faster than many people expect. Most people go home within a day or two, and the neck incision typically heals into a thin line that fades significantly over the following months. Still, it is a real surgery with real risks, and it deserves an honest look. Two possible complications matter most: temporary or, less often, permanent hoarseness or voice change, which can happen if the recurrent laryngeal nerve (a nerve that runs close to the thyroid and controls the vocal cords) is irritated or injured during surgery, and damage to the parathyroid glands (four tiny glands behind the thyroid that control your blood calcium level), which can cause hypoparathyroidism (a condition where calcium levels drop too low), leading to muscle cramps, tingling, or numbness, and often requiring calcium and vitamin D supplements, sometimes for months or, in some cases, permanently.

Because of these risks, the experience of your surgical team matters. Surgeons and surgical centers that perform a high volume of thyroid operations tend to have lower complication rates for both nerve injury and parathyroid injury. It is entirely reasonable to ask a potential surgeon how many thyroid surgeries they perform each year, and to seek a second opinion if you feel uncertain. You are not being difficult by asking these questions. You are being a good advocate for yourself.

Radioactive Iodine (RAI) Therapy

Radioactive iodine, often shortened to RAI or called I-131, is a treatment that takes advantage of a unique feature of thyroid cells: they absorb iodine from the bloodstream more efficiently than almost any other cell in the body, because iodine is a building block for thyroid hormone. Papillary and follicular thyroid cancer cells usually keep this same ability. RAI works by delivering radioactive iodine into your body, where it concentrates in any remaining thyroid tissue and iodine-absorbing cancer cells and delivers radiation directly to them, largely sparing the rest of your body.

Before treatment, most people are asked to follow a low-iodine diet for about one to two weeks. This generally means avoiding iodized salt, dairy products, eggs, seafood, soy, and foods with red dye number 3. The goal is to lower the amount of iodine already in your body so that your cells absorb more of the radioactive iodine during treatment, making it more effective. You will also need a high level of thyroid-stimulating hormone (TSH, a pituitary hormone that tells thyroid cells to take up iodine) before treatment. This is done either by stopping thyroid hormone pills for several weeks, which causes temporary hypothyroidism (low thyroid hormone levels) with symptoms like fatigue and feeling cold, or by receiving injections of a lab-made version of TSH so you can keep taking your hormone pills.

RAI itself is given as a pill or a liquid you swallow (sometimes as an injection), usually in a hospital or outpatient nuclear medicine department. Most people need only one treatment, though a small number need a second. Afterward, your body gives off low levels of radiation for a period of time, so you will be given specific radiation safety precautions to protect people around you, especially young children and anyone who is pregnant. Common instructions include sleeping in a separate bed from others (roughly six feet apart) for several nights, delaying a return to work or public places, avoiding public transportation and air travel for a short period, not preparing food for others, and flushing the toilet twice and wiping the seat after use. Depending on your radiation dose, these precautions typically last anywhere from about three days to two weeks. Your care team will tell you your exact timeline before you leave, and it is worth writing it down or asking for it in writing.

Common side effects include:

Dry mouth
Changes in taste
Soreness or swelling in the neck or salivary glands
Some people also notice dry eyes or, less often, excess tearing

Chewing gum or sucking on hard candy can help with dry mouth. These effects are usually temporary, though occasionally dry mouth persists longer term after higher or repeated doses.

Radioactive iodine does NOT work for medullary thyroid cancer or anaplastic thyroid cancer. This is because MTC starts in C cells and ATC cells have lost the normal thyroid cell features, and neither type absorbs iodine the way papillary and follicular cancer cells do. If you have MTC or ATC, you will not be offered RAI, and that is not an oversight or a sign your cancer is being undertreated. It simply would not work, because the cells cannot take up the iodine that makes the treatment effective in differentiated thyroid cancer. Understanding this distinction can prevent a lot of confusion and worry if you compare notes with someone who has a different type of thyroid cancer.

Thyroid Hormone (TSH Suppression) Therapy

If your thyroid has been removed, your body can no longer make thyroid hormone on its own, so you will take a daily pill called levothyroxine for the rest of your life. This medication replaces the hormone your thyroid used to make, keeping your metabolism, heart rate, energy level, and many other body functions working normally. For people with differentiated thyroid cancer, levothyroxine often does double duty. At a dose higher than what your body would naturally need, it can suppress TSH (thyroid-stimulating hormone) below the normal range. Because TSH can stimulate the growth of any remaining thyroid cancer cells, keeping it low is a deliberate strategy to reduce the chance of recurrence, especially in people whose cancer had higher risk features. People with small, very low-risk cancers are often kept in the normal TSH range instead, since the benefit of suppression is smaller and high doses carry their own risks, including irregular heartbeat and, over time, weakened bones (osteoporosis).

Levothyroxine works best, and most predictably, when it is taken consistently. Most doctors recommend taking it on an empty stomach first thing in the morning, then waiting thirty to sixty minutes before eating breakfast or drinking coffee. Certain substances can block how well your body absorbs the medication if taken too close together, so it is important to separate your dose from calcium supplements, iron supplements, and antacids by at least four hours, and to tell your doctor about any biotin supplements you take, since biotin can interfere with some thyroid blood tests. If you ever miss a dose, most doctors say it is safe to simply take a double dose the next day rather than skip it entirely, but check with your own doctor about what they prefer.

Because everyone absorbs and processes levothyroxine a little differently, and because pregnancy, weight changes, and other medications can all shift how much you need, your doctor will check your TSH level with a blood test periodically, often around six to eight weeks after starting or changing your dose, and then less frequently once your dose is stable. Do not stop or change your dose on your own, even if you feel fine, since the right level is based on lab results as much as symptoms.

Medullary thyroid cancer works differently here too. Because MTC cells come from C cells rather than the follicular cells that respond to TSH stimulation, TSH suppression therapy is not used the same way, or at all, in MTC. People with MTC who have had their thyroid removed still need levothyroxine to replace their thyroid hormone, but the deliberate strategy of pushing TSH below normal to slow cancer growth does not apply, since MTC is not a TSH-driven cancer.

External Beam Radiation Therapy

External beam radiation therapy uses a machine outside the body to aim high-energy rays or particles at a tumor, similar to radiation used for many other cancers. Unlike radioactive iodine, it does not depend on the cancer cells absorbing iodine, so it can be used regardless of thyroid cancer type. In practice, though, it is used more selectively in thyroid cancer than in some other cancers, largely because differentiated thyroid cancer is usually well controlled with surgery and RAI alone.

External beam radiation is most often considered when a tumor cannot be fully removed with surgery, when the cancer does not take up iodine so RAI is not an option, or when the cancer carries a high risk of coming back in the neck. This makes it more commonly relevant for medullary thyroid cancer, anaplastic thyroid cancer, and radioactive iodine-resistant (also called RAI refractory) differentiated thyroid cancer, meaning cancer that no longer responds to RAI. It may also be used to relieve symptoms, such as pain, when cancer has spread to bone or other areas. Because the radiation beam passes through some healthy tissue on its way to the tumor, side effects such as skin irritation, difficulty swallowing, or a sore throat are possible. Techniques like intensity-modulated radiation therapy (IMRT, a precise way of shaping the radiation beam) help doctors aim more accurately and reduce the dose to nearby healthy tissue.

Targeted Therapy and Chemotherapy

When cancer has spread beyond the neck, stopped responding to radioactive iodine, or cannot be controlled with surgery and radiation, doctors increasingly turn to targeted therapy, medications designed to block specific proteins that help certain cancer cells grow. These drugs are different from traditional chemotherapy and often come with different, sometimes more manageable, side effects. Genetic and molecular testing of the tumor helps determine which targeted drug, if any, is likely to help, which is why testing for changes in genes like RET and BRAF (another gene that, when altered, can drive cancer cell growth) has become a routine part of care for advanced thyroid cancer.

Lenvatinib (Lenvima) and sorafenib (Nexavar): Multikinase inhibitors (drugs that block several growth-related proteins at once) approved for radioactive iodine-refractory differentiated thyroid cancer, meaning papillary or follicular cancer that RAI no longer controls. Both are taken as daily pills and can slow cancer growth for a period of time, though they are not a cure.
Selpercatinib (Retevmo): A RET inhibitor that targets an abnormal RET protein caused by certain RET gene changes. The FDA granted selpercatinib full approval in September 2024 for advanced or metastatic medullary thyroid cancer with a RET mutation in patients aged two and older, after first receiving accelerated approval for this use in 2020. It is also used for RET fusion-positive thyroid cancers when RAI is not a good option.
Pralsetinib (Gavreto): Another RET inhibitor, approved by the FDA in December 2020 for advanced or metastatic RET mutant medullary thyroid cancer and for RET fusion-positive thyroid cancer that no longer responds to radioactive iodine (or for which RAI is not appropriate). Like selpercatinib, it is taken by mouth.
Dabrafenib (Tafinlar) plus trametinib (Mekinist): A combination of two pills that the FDA approved in 2018 for locally advanced or metastatic anaplastic thyroid cancer with a BRAF V600E gene change, in people who have no other satisfactory local treatment options. Dabrafenib blocks the abnormal BRAF protein and trametinib blocks a related protein called MEK. Used together, this combination has made a real, meaningful difference for a cancer that historically offered patients very few options, and it is one of the most important advances in anaplastic thyroid cancer treatment in recent years.
Vandetanib (Caprelsa) and cabozantinib (Cometriq or Cabometyx): Multikinase inhibitors used for advanced medullary thyroid cancer, whether or not a RET change is found. Vandetanib carries a risk of serious heart rhythm problems, so doctors must complete special training before prescribing it.
Chemotherapy: Traditional chemotherapy plays a limited role in most thyroid cancers, since differentiated and medullary thyroid cancers often respond better to targeted drugs. Chemotherapy has a more meaningful, if still difficult, role in anaplastic thyroid cancer, where it is often combined with radiation to make the radiation more effective. Commonly used drugs include doxorubicin, paclitaxel, docetaxel, cisplatin, and carboplatin. Side effects vary by drug and can include nausea, fatigue, low blood counts, heart function changes (with doxorubicin), and nerve-related symptoms like tingling or numbness in the hands and feet (with cisplatin, carboplatin, or paclitaxel).

If you are interested in newer treatments being studied, including for cancer that has stopped responding to standard options, joining a clinical trial is worth discussing with your oncologist.

Click and connect your medical records for a personalized list of treatments

Treatment for Anaplastic Thyroid Cancer

Anaplastic thyroid cancer deserves its own section because it is treated so differently from the rest of this guide, and because time matters so much. ATC is rare, making up under 2 percent of all thyroid cancers, but it grows and spreads far faster than papillary, follicular, or medullary thyroid cancer. Because of this, a new ATC diagnosis is treated as a medical emergency requiring evaluation within days by a multidisciplinary team, meaning a surgeon, medical oncologist, radiation oncologist, and endocrinologist working together from the start, ideally at a center with experience treating this specific cancer.

One of the first and most urgent steps is molecular testing of the tumor for a BRAF V600E gene change, because the result directly changes which treatments are available. If surgery is possible without unacceptable risk, it is generally recommended. Many tumors, however, are too large, too invasive, or too widely spread for surgery to be an option. In those cases, treatment typically combines external beam radiation with chemotherapy, or, if the tumor carries a BRAF V600E mutation, targeted therapy with dabrafenib plus trametinib, sometimes starting before surgery is considered to shrink the tumor first.

It would not be honest to soften how serious this diagnosis is. Historically, average survival after an anaplastic thyroid cancer diagnosis has been measured in months rather than years, and it remains one of the most difficult cancers to treat. At the same time, it would also not be honest to leave out real progress. The approval of dabrafenib plus trametinib for BRAF-mutated anaplastic thyroid cancer has changed outcomes for a meaningful share of patients whose tumors carry that specific mutation, and long-term survivors do exist, including some who were not candidates for surgery. Palliative care, meaning care focused on relieving symptoms such as difficulty breathing, swallowing problems, or pain, is often introduced early alongside cancer treatment, not instead of it, and can meaningfully improve quality of life at any stage.

If you or a family member has just been diagnosed with ATC, finding a doctor or center experienced with this specific cancer, asking about BRAF testing right away, and asking about clinical trials are three of the most useful things you can do in the first days after diagnosis.

Managing Treatment Side Effects and Support

Getting through thyroid cancer treatment does not end when surgery or radiation is finished. If you developed hypoparathyroidism after surgery, you may need to take calcium and vitamin D supplements on an ongoing basis, and your doctor will monitor your blood calcium level periodically to adjust the dose. Symptoms like tingling around the mouth or in the fingers can be an early sign your level is dropping and worth reporting promptly.

If surgery affected your voice, whether from temporary swelling or an injury to the nerve that controls your vocal cords, voice therapy with a speech-language pathologist can help you regain strength and clarity, and most voice changes improve significantly over weeks to months. It is also completely normal to feel self-conscious about a neck scar, especially in the first months when it is still pink or raised. Scars generally fade substantially over six to twelve months, and simple measures like sunscreen on the area can help it fade evenly.

Beyond the physical side effects, many people find the emotional weight of thyroid cancer, the fear of recurrence, the adjustment to lifelong medication, and the disruption to daily life harder to manage than expected, especially since others may assume this cancer is "the good one" and downplay what you are going through. You do not have to carry that alone. For more on living well after treatment, understanding what your survival statistics do and do not mean for you personally, and connecting with others who understand, visit our guide to thyroid cancer support resources and our list of questions to ask your care team at any stage of treatment or follow-up.