Thyroid Cancer: Introduction
What is cancer?
Cancer starts when cells in the body change (mutate) and grow out of control. To help you understand what happens when you have cancer, let’s look at how your body works normally. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body doesn’t need them any longer.
Cancer is made up of abnormal cells that grow even though your body doesn’t need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby tissues. They can even spread to other parts of the body (metastasize).
What is the thyroid gland?
The thyroid gland is part of the endocrine system. It makes and helps control hormones in your body. It’s in the front of your neck, over your windpipe (trachea). It’s below your Adam’s apple and above your collarbone. You often can’t see or feel your thyroid.
It’s shaped like a butterfly with 2 lobes, a right and left lobe. The lobes are joined by a bridge of tissue, called the isthmus.
The thyroid is made up of 2 main types of cells:
Follicular cells. These use iodine to make thyroid hormones. These hormones help control your metabolism.
C cells or parafollicular cells. These make the hormone calcitonin. This helps control calcium levels and how calcium is used in your body.
What is thyroid cancer?
Thyroid cancer starts in the cells that make up the thyroid gland.
There are 5 main types of thyroid cancer (or carcinoma):
Papillary cancer. This is the most common type. It starts in the follicular cells. It tends to form in only 1 side of the thyroid gland and grow slowly.
Follicular cancer. This cancer also forms in the follicular cells of thyroid cancer. It’s the next most common types and accounts for about 10% of all cases. It’s more common in countries where people don’t get enough iodine in their diet.
Hurthle cell cancer. This is a rare form of follicular thyroid cancer. It’s harder to find and treat. It tends to not cause symptoms and has often spread to nearby lymph nodes by the time it’s found.
Medullary thyroid cancer (MTC). This is a rare type of thyroid cancer that starts in the C cells. It produces a lot of calcitonin and tends to spread.
Anaplastic cancer. This is also called undifferentiated thyroid cancer. It’s very rare. It tends to grow and spread quickly. It’s hard to treat.
Most thyroid changes are not cancer
Changes in the thyroid gland are often easy to see and feel. Lumps or bumps, called nodules, are common. Most of them are not cancer (benign). And they may not need to be treated. Growths that are not cancer don’t spread from the thyroid to other parts of your body.
Thyroid adenomas are small nodules that start in the thyroid gland. They’re not cancer. Many times they’re only found while looking at the area around the thyroid for another reason.
Some thyroid adenomas make thyroid hormone. If an adenoma makes too much thyroid hormone, it can cause hyperthyroidism. This is when there’s too much thyroid hormone in your body. It can cause severe tiredness (fatigue), sweating, tremors, and palpitations. It may need to be treated.
Some signs that a nodule may be cancer and not an adenoma or other benign nodule include:
The nodule is not making hormones
The nodule is solid instead of filled with fluid, like a cyst
The nodule grows fast
Lymph nodes around the thyroid gland are swollen
How thyroid cancer spreads
When thyroid cancer spreads outside the thyroid gland, it most often goes to nearby lymph nodes first. It can also spread to nearby blood vessels and other tissues in the neck. Over time, it can spread to distant parts of the body, such as the lungs and bones.
Talk with your healthcare provider
If you have questions about thyroid cancer, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.
Thyroid Cancer: Risk Factors
What is a risk factor?
A risk factor is anything that may increase your chance of having a disease. Risk factors for a certain type of cancer might include tobacco use, unhealthy diet, excess weight, decreased physical activity, family history, or many other things. The exact cause of someone’s cancer may not be known. But risk factors can make it more likely for a person to have cancer.
Things you should know about risk factors for cancer:
Risk factors can increase your risk, but they don’t always cause the disease.
Some people with 1 or more risk factors never get cancer. Other people with cancer have no known risk factors.
Some risk factors are very well known. But experts are studying risk factors for many types of cancer.
Some risk factors may not be in your control. This includes your family history, age, or gender. But others may be things you can change. Knowing about risk factors can help you make choices that might lower your risk. For instance, if an unhealthy diet is a risk factor, you may choose to eat healthy foods. If excess weight is a risk factor, your healthcare provider may help you lose weight.
Who is at risk for thyroid cancer?
Risk factors for thyroid cancer include:
Gender. Women are 3 times more likely than men to have thyroid cancer.
Age. Thyroid cancer can happen at any age. But it’s more common in women in their 40s and 50s, and men in their 60s and 70s.
History of radiation exposure. Your risk is higher if you had radiation treatments to your neck or throat as a child. Exposure to low doses of radiation in medical diagnostic tests as a child may increase your risk of developing thyroid cancer, too. It’s also higher if you were exposed to nuclear fallout from power plant accidents or nuclear weapons.
Iodine deficiency. A diet low in the mineral iodine raises your risk.
Family history. People with certain inherited genetic diseases that are passed down in families are at higher risk. These include familial medullary thyroid cancer (FMTC), Cowden disease, multiple endocrine neoplasia type 2A syndrome (MEN2A), and multiple endocrine neoplasia type 2B syndrome (MEN2B).
Goiter. A goiter is an enlarged thyroid. If you have had a goiter or a family history of thyroid disease, you may be at an increased risk for thyroid cancer.
What are your risk factors?
Talk with your healthcare provider about your risk factors for thyroid cancer and what you can do about them.