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Thyroid Cancer Symptoms: What to Watch For and When to See a Doctor
If you or someone you love has found a lump in the neck or is trying to make sense of new symptoms, this guide walks through the signs of thyroid cancer in plain language. It covers the common symptoms of thyroid cancer, the less common ones, the very different and urgent symptoms of anaplastic thyroid cancer, and what advanced disease can look like. As always, this is general education, not a diagnosis. If you notice any of the symptoms below, talk with your doctor so the cause can be found.
What Are the Signs and Symptoms of Thyroid Cancer?
Here is the most important thing to know before anything else: most thyroid cancer causes no symptoms at all in its early stages. Many people find out they have a thyroid nodule (a lump or growth in the thyroid gland, a small butterfly shaped gland at the base of the front of the neck) only because they or their doctor happened to feel it, or because it showed up by chance on an imaging test done for a completely different reason, such as a carotid ultrasound (a scan of the neck arteries) or a neck or chest CT scan. This kind of incidental discovery is actually one of the most common ways thyroid cancer is found today.
That fact leads to the second most important thing to know: finding a lump in your thyroid does not mean you have cancer. Thyroid nodules are extremely common. By some estimates, about half of all adults will have a thyroid nodule that can be found by examination or imaging by the time they reach age 60, and more than 9 out of 10 of those nodules turn out to be benign (not cancer). This is true even for nodules that are large or that have been there for years. A nodule being big or long-standing does not, by itself, say much about whether it is cancer.
Because most thyroid nodules and early thyroid cancers cause no symptoms, the way many people find out something needs a closer look is through a routine neck exam by their doctor, or through blood tests and imaging done for other reasons. This is different from the pattern you might expect with other cancers, where symptoms often drive people to seek care. With thyroid cancer, especially differentiated thyroid cancer (a term that covers papillary and follicular thyroid cancer, which together make up the large majority of cases), the workup usually starts with a nodule that was found rather than a symptom that was felt.
When symptoms do appear, they usually happen because a tumor has grown large enough to press on nearby structures in the neck, such as the windpipe, the food pipe (esophagus), or the nerve that controls the vocal cords. The symptoms described in this guide, a lump, voice changes, trouble swallowing, and others, can also be caused by many things that are not cancer, including goiter (an enlarged thyroid gland), Hashimoto thyroiditis, Graves disease, and simple benign nodules or cysts. Seeing a doctor is the only way to know for sure what is causing a symptom.
(Source: National Cancer Institute)
In the United States, doctors estimate about 45,240 new cases of thyroid cancer are diagnosed each year, and thyroid cancer is almost three times more common in women than in men. About 8 out of 10 thyroid cancers are the papillary type, and roughly 1 out of 10 are follicular, which together make up differentiated thyroid cancer. The remaining share includes rarer types with very different behavior and, in some cases, very different symptoms.
A note before you keep reading: anaplastic thyroid cancer is different
Almost everything in this guide so far, and most of what follows, describes differentiated thyroid cancer, which is the most common form and usually grows slowly. Anaplastic thyroid cancer (ATC) is a separate and much more aggressive disease that causes a very different, much faster, and more urgent symptom pattern. It is rare, making up only about 2% of thyroid cancers, but it needs to be recognized quickly. We cover its symptoms in detail later in this guide, in a section clearly labeled for that purpose, so you can tell the difference.
What Are the Most Common Symptoms of Thyroid Cancer?
When thyroid cancer does cause symptoms, certain ones show up more often than others. These are the symptoms most people associate with thyroid cancer, and they overlap closely with the symptoms of many benign thyroid conditions, which is exactly why a medical evaluation matters so much.
A lump or nodule in the front of the neck: This is the most common way thyroid cancer is noticed. You or your doctor might feel a firm area low in the front of the neck, near the base of the throat. Many people first notice it while looking in a mirror, buttoning a collar, or fastening a necklace.
Swelling in the neck: Sometimes the whole area looks or feels puffy or fuller than usual, rather than one clear lump. This can be more subtle and easier to miss than a distinct nodule.
Difficulty swallowing: If a nodule or tumor grows large enough to press on the esophagus (the tube that carries food from the mouth to the stomach), swallowing food or even saliva can start to feel harder or uncomfortable.
Hoarseness or voice changes that do not go away: Your vocal cords are controlled by a nerve called the recurrent laryngeal nerve, which runs very close to the thyroid gland. If a tumor presses on or grows into this nerve, it can change how your voice sounds, making it hoarse, weaker, or different than usual. Voice changes from thyroid cancer tend to persist rather than come and go as a cold-related hoarseness would.
Pain in the neck, sometimes radiating to the ears: Some people feel a dull ache or pressure in the front of the neck. This pain can sometimes travel or be felt up toward the jaw or ears, which can be confusing since the pain does not seem to be coming from the ear itself.
Swollen lymph nodes in the neck: Lymph nodes are small, bean-shaped structures that are part of the immune system, and they sit in clusters throughout the neck. If thyroid cancer spreads to nearby lymph nodes, they can become enlarged and sometimes felt as separate small lumps on the side of the neck, apart from the thyroid gland itself.
These symptoms can develop slowly over months or even years with differentiated thyroid cancer, which is one reason it is so often found before it causes obvious problems. It is also worth repeating that every one of these symptoms, including a neck lump, is far more often caused by something other than cancer. Still, any new or persistent version of these symptoms is worth having checked by a doctor, ideally one experienced with thyroid cancer diagnosis.
What Are the Less Common Symptoms of Thyroid Cancer?
Beyond the more familiar symptoms, a smaller number of people experience symptoms that are less common but still worth knowing about, especially because one pattern described below signals a medical emergency.
Difficulty breathing can occur if a thyroid tumor grows large enough to press on the trachea (the windpipe). This is not a common early symptom, since it usually takes significant growth for a tumor to affect breathing, but it is important to mention because it can develop gradually enough that people sometimes attribute it to other causes, like being out of shape or having allergies. A constant cough that is not related to a cold or respiratory infection is another less common symptom, and again, it usually points to a tumor pressing on the airway.
Perhaps the single most important point in this entire guide, worth repeating one more time, is that many small thyroid cancers cause no symptoms whatsoever. They are found on a neck exam, on imaging done for another reason, or occasionally during surgery for something unrelated. This is especially true for small papillary thyroid cancers, which are the most common type and often grow very slowly.
Anaplastic thyroid cancer symptoms: a medical emergency with a very different pattern
Anaplastic thyroid cancer (ATC) behaves so differently from the rest of this guide that it deserves its own clearly labeled section. ATC is rare, but it is one of the most aggressive cancers that exists, and its symptom pattern reflects that. Instead of a slow-growing lump that develops over months or years, ATC typically causes a neck mass that grows rapidly, often over just days to a few weeks. This kind of fast growth is unusual for thyroid conditions and is a major warning sign in itself.
Along with rapid growth, ATC commonly causes pain and difficulty breathing or swallowing that can worsen quickly, sometimes within the same short time frame as the mass itself is growing. Hoarseness is also common, since ATC frequently invades the nerve that controls the vocal cords or the voice box area directly. Because ATC grows and invades surrounding neck structures so quickly, some patients need urgent procedures to protect their airway.
If you or someone you know notices a neck mass that is visibly getting bigger over a matter of days to weeks, especially if it comes with new pain, breathing trouble, or worsening swallowing difficulty, this needs same-day or next-day medical attention. Do not wait to see if it resolves on its own. ATC requires urgent evaluation by a multidisciplinary care team, and while it is a serious and much more aggressive disease than differentiated thyroid cancer, getting evaluated quickly gives doctors the best chance to start treatment promptly. It is worth remembering that this pattern is not what happens with the vast majority of thyroid nodules or with differentiated thyroid cancer, so this warning is specific to sudden, rapid neck mass growth rather than the slower changes described earlier in this guide.
What Are the Symptoms of Advanced (Metastatic) Thyroid Cancer?
Most thyroid cancer is caught before it spreads widely, but it is still useful to understand what symptoms can occur if the cancer does spread (metastasize) beyond the thyroid gland. The most common place thyroid cancer spreads to first is the lymph nodes in the neck, which can become enlarged and felt as lumps separate from the thyroid itself, sometimes even before the original tumor is easy to feel.
Less commonly, differentiated thyroid cancer can spread further, most often to the lungs or to bone. Spread to the lungs can cause a cough or shortness of breath, symptoms that can be easy to mistake for a respiratory illness. Spread to bone can cause localized pain in the affected area, which may come on gradually and persist. These symptoms are far more likely to occur in cancer that has been present for a long time without treatment, or in less common, more aggressive subtypes, rather than in typical, early-stage differentiated thyroid cancer.
A distinctive symptom pattern in advanced medullary thyroid carcinoma
Medullary thyroid carcinoma (MTC) works differently from papillary and follicular thyroid cancer, and it deserves its own note here. MTC develops from a different kind of thyroid cell, called a C cell, which normally produces a hormone called calcitonin (a hormone that helps regulate calcium levels in the blood). When MTC is advanced, calcitonin levels can become very high, and this can sometimes cause flushing (a feeling of warmth and reddening of the skin, especially in the face) or diarrhea. This is a distinctive symptom pattern that is not seen with papillary or follicular thyroid cancer, and it is less well known to patients, so it is worth understanding if you or a family member has been diagnosed with MTC or is being evaluated for it.
Because MTC can run in families, linked to changes in a gene called RET, anyone diagnosed with MTC is generally advised to have genetic testing, and close relatives may need testing and monitoring too. You can read more about this in our guide on risk factors for thyroid cancer. If you are experiencing new flushing or diarrhea along with a known or suspected thyroid nodule, mention it specifically to your doctor, since it is not a symptom most people think to connect to a thyroid problem. Whatever symptoms you are noticing, your own care team is the right place to bring your questions, since they can examine you, order the right tests, and explain what your particular situation means. For a fuller picture of what happens after symptoms lead to a workup, see our guide on how thyroid cancer is diagnosed.