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What is the thyroid gland?
The thyroid is part of the body's endocrine system, a system of glands that control hormones in the body. It normally weighs less than an ounce, and it cannot be seen or felt in most people; however it has an important function. The thyroid makes hormones that help regulate the body's heart rate, blood pressure, temperature and metabolism (the breakdown of food to create energy).
The thyroid has two halves, or lobes, one on each side of the neck. It wraps around the trachea (windpipe) just under the larynx (Adam's apple). A thin strip of tissue known as the isthmus connects the two halves.
Thyroid gland cells are the only cells in the body that absorb and retain iodine. Iodine is needed to make thyroid hormones.
Two kinds of cells are found in the thyroid:
- Follicular cells are the most common. They produce thyroid hormone, which is important for growth, mental function and helping the body create energy.
- Parafollicular cells (also known as C cells) produce a small amount of the hormone calcitonin, which has a minor role to control calcium metabolism. Most parafollicular cells are in the upper third of each lobe.
What are the different types of thyroid cancer?
Papillary, follicular and anaplastic thyroid cancers begin in the follicular cells. Papillary and follicular cancers—the most common thyroid cancers—are sometimes referred to together as differentiated thyroid cancer. They have similar treatment.
Papillary thyroid cancer accounts for about 80% of thyroid cancers. While papillary thyroid cancer typically occurs in only one lobe of the thyroid gland, it may arise in both lobes in up to 10% to 20% of cases. Papillary thyroid cancer is most common in women of childbearing age. It sometimes is caused by exposure to radiation.
Even though papillary thyroid cancer is usually not an aggressive type of cancer, it often metastasizes (spreads) to the lymph nodes in the neck. Papillary thyroid cancer treatment usually is successful.
Follicular thyroid cancer accounts for about 10% of thyroid cancers. Like papillary thyroid cancer, follicular thyroid cancer usually grows slowly. Its outlook is similar to papillary cancer, and its treatment is the same.
Follicular thyroid cancer usually stays in the thyroid gland but sometimes spreads to other parts of the body, such as the lungs or bone. However, it usually does not spread to lymph nodes. It is more common in countries where diets do not contain enough iodine.
Hurthle cell carcinoma, also called oxyphil cell carcinoma, is a type of follicular thyroid cancer. Most patients diagnosed with Hurthle cell cancer do well, but the outlook may change based on the extent of disease at the time of diagnosis.
Medullary thyroid cancer (MTC) is the only type of thyroid cancer that develops in the parafollicular cells of the thyroid gland. It accounts for 3% to 10% of thyroid cancers. Medullary thyroid cancer cells usually make and release into the blood proteins called calcitonin and/or carcinoembryonic antigen, which can be measured and used to follow the response to treatment for the disease.
Sometimes medullary thyroid cancer spreads to the lymph nodes, lungs or liver before a nodule is found or the patient has symptoms. MTC can be treated more successfully if it is diagnosed before it has spread.
There are two types of MTC:
- Sporadic MTC is more common, accounting for 85% of medullary thyroid cancers. It is found mostly in older adults and is not inherited.
- Familial MTC is inherited, and it often develops in childhood or early adulthood. If familial MTC occurs with tumors of certain other endocrine organs (parathyroid and adrenal glands), it is called multiple endocrine neoplasia type 2 (MEN 2). If you have a family history of MTC, it is important for you and your children to be tested for the gene that causes the disease.
Anaplastic thyroid cancer makes up only 1% of thyroid cancer, but is the most dangerous type. It is believed that anaplastic thyroid cancer grows from a papillary or follicular tumor that mutates further to this aggressive form. Anaplastic thyroid cancer, sometimes called undifferentiated thyroid cancer, spreads rapidly into areas such as the trachea, often causing breathing difficulties.
Thyroid cancer statistics
According to the National Cancer Institute, about 53,000 people are diagnosed with thyroid cancer each year in the United States. About 75% of these are women, making it the eighth-most-common cancer in women. Thyroid cancer is seen most often in adults, with two-thirds of the cases occurring between ages 20 and 55.
Thyroid cancer is usually a slow-growing cancer. It is one of the least dangerous cancers in most cases, and the five-year thyroid cancer survival rate is more than 98%.
What are the risk factors for thyroid cancer?
Although the exact cause of thyroid cancer has not been identified, certain risk factors have been identified. They include:
- Age: Two-thirds of thyroid cancer cases occur between ages 20 and 55.
- Gender: Women are three times as likely as men to develop thyroid cancer. Papillary thyroid cancer is found most often in women of childbearing age.
- Exposure to radiation, including X-rays, especially during childhood
- Inherited disorders: Familial medullary thyroid cancer usually is caused by an inherited mutation in the RET gene. If your parent has the gene mutation, you have a 50% chance of having it too. If you inherit the gene, you are likely to develop the cancer. Other types of thyroid cancer also may be caused by diseases that run in families.
- Iodine deficiency: This is uncommon in the United States, where iodine often is added to table salt. In other areas of the world, especially inland regions without fish and shellfish in the diet, iodine levels are sometimes too low.
Not everyone with risk factors gets thyroid cancer. However, if you have risk factors, it’s a good idea to discuss them with your doctor.
Learn more about thyroid cancer:
Some cases of thyroid cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family on our genetic testing page.
Why choose MD Anderson for thyroid cancer treatment?
At MD Anderson, you receive customized care for thyroid cancer from a team of renowned experts in the Endocrine Center. Their level of experience and expertise in treating every type of cancer is among the most impressive in the nation. This increases your chance for successful treatment.
Your personal medical team is made up of experts from several specialties. They work together, communicating and collaborating with each other and with you, to ensure you receive seamless, coordinated care.
If your treatment for thyroid cancer includes surgery, our talented surgeons use the most advanced techniques that are proven to have good results. In some cases, video-assisted or robotic surgery may be used, while minimizing or eliminating a neck scar.
We are at the forefront of research on how to better treat and prevent thyroid cancer. In fact, we led an international study that showed patients with certain types of papillary or follicular thyroid cancer do best when they are treated with surgery, radioactive iodine and thyroid hormone suppression therapy.
As leaders in thyroid cancer research, we are able to offer a number of clinical trials of innovative therapies.
Every day is a new day to live. I choose to live an incredible life no matter my diagnosis.
BY Max Nickless
In January 2017, I was diagnosed with anaplastic thyroid cancer. The disease was so advanced that I was given only a few weeks to live. So, when I first started my battle against cancer, I was just hoping to gain a bit more time. I never dreamed I’d still be here today.
Yet here I am, almost two years later. I am completely cancer-free — and I have MD Anderson to thank for it.
I knew very little about thyroid cancer or its treatment before I was diagnosed. Even now, most of the medical stuff is over my head. But one thing I do understand is hope. And I found a lot of that at MD Anderson.
My anaplastic thyroid cancer symptoms
I had a lot of swelling in my neck for several weeks before my diagnosis. I was also unusually tired and irritable. I thought it was just weight gain at first, so I didn’t go to the doctor. But when I started having trouble breathing and swallowing, I went to a local emergency room, near my home in Indiana.
The doctors there performed a CT scan, which showed a large mass in my neck, as well as several cancerous lymph nodes. The tumor was so big that it had completely surrounded one of my carotid arteries and almost flattened my windpipe. That made breathing difficult and swallowing even harder.
Why I came to MD Anderson
The size and location of the tumor made surgery impossible. My local hospital is great and its doctors are talented, but their experience with my type of cancer was extremely limited. They didn’t know of any other treatments that could help me, so the best they could offer was to keep me comfortable. My doctors suggested I get my affairs in order and recommended hospice care.
Luckily, my wife would not accept that diagnosis. She started looking around and discovered that MD Anderson was doing research on my exact type of cancer. She called and spoke to someone in the Endocrine Center. A few hours later, Dr. Maria Cabanillas called her back, and by the next morning, I had appointments scheduled at MD Anderson for the following Monday.
Considering a clinical trial
At first, Dr. Cabanillas recommended a clinical trial involving two targeted therapy drugs: dabrafenib and trametinib. The combination had already been approved as a treatment for metastatic melanoma, and it was now being studied for use in treating anaplastic thyroid cancer.
But by the time I got to MD Anderson, I couldn’t even swallow water anymore, much less a pill. So I was not eligible to participate.
Still, Dr. Cabanillas thought that particular combination of drugs could help me, so I got my first dose of dabrafenib through a feeding tube on the evening of Feb. 23, 2017. I started taking trametinib about a month later and an immunotherapy drug called pembrolizumab about a week after that.
My anaplastic thyroid cancer treatment
The idea was to shrink the tumor first, remove it once it was smaller, then kill anything left behind with radiation therapy. I had surgery on May 30, about three months after I started treatment. My surgeon, Dr. Mark Zafereo, completely removed my thyroid, as well as some diseased lymph nodes. After that, I had 30 doses of radiation therapy under Dr. Adam Garden.
I’m not sure exactly how much the drugs shrank the tumor, but I do remember seeing a side-by-side comparison of pictures taken in February and May. The difference was dramatic. Just two days after my first dose of dabrafenib, I was able to take a sip of water and swallow it. A few weeks later, breathing became easier, too. My tumor responded so quickly to the treatment that I ended up only needing the feeding tube for two weeks, instead of the six weeks my doctors had expected.
My life after thyroid cancer
I still take dabrafenib and trametinib pills daily. I also get an infusion of pembrolizumab every three weeks. And, because my thyroid was completely removed, I’ll have to take a synthetic thyroid hormone pill (levothyroxine) every day for the rest of my life.
Due to those medications, there are about six hours out of each day that I’m not allowed to eat. Sometimes, I get a fever or chills, and I can’t talk for as long as I used to. But that’s OK. Because I can still do almost everything else I did before cancer. I just don’t do them quite as fast or have as much stamina.
I used to have a very loud, projecting voice. I coached basketball for years, and could be heard all over the gymnasium. I can’t yell now, though, so coaching is a thing of the past. But I still work, hunt, play golf and roughhouse with my grandkids. And I have no trouble swallowing, so there’s nothing I can’t eat.
I realize that cancer could raise its ugly head at any time, but I’ve shown no evidence of disease since September 2017. I suspect I’ll be around for a while. My life is different now, but it’s still good. So, don’t give up, even if you’re told it’s hopeless. There is always hope. And I’m the proof.
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