Overview
The thyroid is a small, butterfly-shaped gland that produces and releases hormones. It sits low in the front of your neck, just behind the little dip where your collarbones meet. Thyroid cancer isn't very common and happens more often in women than in men. There are a few different types, and the kind you have will guide your treatment.
Thyroid cancer begins in the thyroid gland, a small, butterfly-shaped organ located at the front of your neck. It has two parts, called lobes, which sit on either side of your windpipe and are connected by a thin strip of tissue called the isthmus. The thyroid makes hormones that help regulate your metabolism, control your body temperature, and manage how your body uses energy and oxygen.
This type of cancer starts when cells in the thyroid begin to grow in an abnormal and uncontrolled way. These cells can build up to form a lump, also called a tumor. In most cases, thyroid cancer grows slowly and may not cause noticeable symptoms at first. Some people might discover it during a routine checkup or after noticing a painless lump in the neck. Although it can spread to nearby tissues or lymph nodes, thyroid cancer is often treatable, especially if found early.
Thyroid cancer is grouped by how closely the cancer cells resemble normal thyroid cells under a microscope, either differentiated (more like normal cells) or undifferentiated (less like normal cells). It's also classified by the type of cell it starts in. The four main types are papillary, follicular, medullary, and anaplastic.
Papillary thyroid cancer (also called papillary carcinoma) is the most common type, making up about 80% to 85% of cases. It’s a slow growing, differentiated cancer that starts in follicular cells and usually affects one or both lobes of the thyroid.
This cancer may spread to nearby lymph nodes in the neck, but with proper treatment, the long-term outlook is usually very good.
The second most common type, follicular thyroid cancer (or follicular carcinoma), is also a differentiated cancer. It tends to occur more often in areas where people don’t get enough iodine in their diet.
Follicular cancer doesn’t usually spread to lymph nodes, but it’s more likely than papillary cancer to spread to other organs like the lungs or bones. Even though it can be a bit more aggressive, most people still have a good chance of recovery with treatment. A rare subtype called Hürthle cell carcinoma (also known as oxyphil cell carcinoma) falls under follicular cancer and makes up less than 5% of all thyroid cancer cases.
Medullary thyroid cancer (or medullary carcinoma) starts in the C-cells of the thyroid, which make a hormone called calcitonin. This type is more aggressive and less differentiated than papillary or follicular cancers. It accounts for about 4% to 10% of thyroid cancer cases.
Medullary cancers are more likely to spread to lymph nodes and other parts of the body. They often produce high levels of calcitonin and CEA (carcinoembryonic antigen), which can be picked up in blood tests during diagnosis.
Anaplastic thyroid cancer (or anaplastic carcinoma) is the rarest and most aggressive form, making up around 2% to 3% of cases. It’s the most undifferentiated type, meaning the cells look very different from normal thyroid cells.
This cancer spreads quickly to the neck and other areas, and it’s the hardest to treat. Because of how fast it grows, it usually requires immediate and intensive care.
