When the cells of the thyroid gland begin to multiply at an unregulated rate, the condition is called thyroid cancer. The thyroid gland is shaped like a butterfly and sits below the voice box. As an important component of the endocrine system, the thyroid plays an important role in releasing the hormones that control metabolism.
The most common indication of these problems comes when an individual or their medical professional notices an unusually large or out of shape thyroid gland. This will usually happen in a physical examination or when the individual is massaging or touching the front of their neck. However, there are a variety of conditions that can result in an abrupt change in the size, texture, or shape of the thyroid gland, and cancer is not necessarily the most common. It will be necessary to perform a full array of medical evaluations to assess the function of the thyroid and delineate the shape of this gland shape will need to be performed as well.
Other conditions that can also result in an enlarged thyroid include inflammation from Hashimoto Disease and iodine deficiency.
Sometimes after the thyroid is fully evaluated, the results show the presence of thyroid nodules or tumors. Even still, 90% of these nodules are benign.
There has been an increase in thyroid diagnosis throughout the modern world, but this is most likely due to improved detection technology rather than an increase in cancer cases. Women are three times as likely to contract this form of cancer as men.
Thyroid cancer ranks the 8th most common kind of cancer in the US, with an estimated 65,000 new cases being diagnosed each year. The good news is that most of the prognostics are good and even better if they have not spread to other areas of the body, this is true for the two most common types of cancer that we will explore below.
Types:
There are four major types of thyroid cancer. Each type of cancer attacks a different region of the thyroid, and this can affect prognosis and treatment.
These are the major types of cancer:
- Papillary thyroid cancer – 80% of thyroid cancers are papillary cancer making this the most common type of cancer of them all. These cancers do not grow quickly and are not usually fatal.
- Follicular thyroid cancer – the second most common type of thyroid cancer accounts for more than 10% of all thyroid cancer cases. This condition is especially common in countries that do not have enough iodine in the diet. Hürthle cell carcinoma accounts for almost 3% of thyroid cancer cases and is a form of follicular thyroid cancer.
- Medullary thyroid cancer – accounting for 4% of all thyroid cases, medullary thyroid cancer can appear from nowhere, or the gene can be inherited. When the condition I inherited, it is because of a mutation in the RET gene and typically linked to MEN, or multiple endocrine neoplasia type 2. This type of cancer typically requires a variety of treatments and is not as easy to treat as some of the other forms of thyroid cancer.
- Anaplastic thyroid cancer – also known as undifferentiated carcinoma, is the rarest of the common types of thyroid cancer, with only 2% of thyroid cancers falling in this category. It does spread fast and is especially hard to treat.
Most cases of thyroid cancer can be treated effectively if they are caught early. Even those with follicular or papillary thyroid cancers have a positive prognosis so long as the condition is diagnosed early in its development. According to statistics by the American Cancer Society, 97% of all cases will survive10 years after the initial diagnosis.
Most thyroid cancers are now found early when they are treatable. Many people with papillary and follicular thyroid cancer have a good prognosis. According to the American Cancer Society, 97% of people with thyroid cancer are alive 10 years after diagnosis.
Causes
There are not many cases when the specific causes of thyroid cancer are known. But there are some factors, such as age, sex, radiation exposure, and genetic predisposition, that can increase the risk of contracting thyroid cancer.
In most cases, the specific causes of thyroid cancer are not known. However, there are risk factors associated with age, gender, genetics, and radiation exposure:
- Gender – as mentioned, women are two to three times more likely to contract thyroid cancer
- Age – 66% of all thyroid cancer cases occur in people between the ages of 22 and 55.
- Exposure to Radiation – X-rays, as a part of routine medical examinations, are not considered a factor in thyroid cancer. Nevertheless, there are some types of radiation exposure that can lead to a higher risk of thyroid cancer. This includes radiation treatment performed before the 1960s and those used to treat Hodgkin disease or breast cancer.
- Family History – a history of certain conditions in the family can increase the likelihood of developing thyroid cancer. This includes multiple endocrine neoplasia (MEN), medullary thyroid cancer, precancerous colon polyps, and/or goiters.
- Genetics – A mutation in the RET gene is the cause of some cases of medullary thyroid cancer. Those with a family history of MTC or multiple endocrine neoplasia (MEN) a blood test will reveal the presence of this mutation.
Signs and Symptoms
There are a variety of conditions that can have symptoms very similar to those caused by thyroid cancer. For example, the presence of nodules or lumps on the thyroid is common, but they are not usually cancerous.
Nevertheless, there are yet no screening services available for this type of cancer. This means that it will be up to the individual to work with their medical professional to create a plan to detect this condition early.
If you notice any of the following warning signs of thyroid cancer, you will want to let your medical practitioner know right away:
- A lump on the neck
- Neck swelling
- Voice changes, including hoarseness
- Trouble breathing
- Trouble swallowing
- Swollen lymph nodes without any respiratory conditions
Laboratory tests
Screening
Those who do not have any symptoms of thyroid cancer and have an average risk of developing this condition are not advised to seek out screening tests.
But those who do have a family history of medullary thyroid cancer (MTC) or multiple endocrine neoplasia (MEN 2), may consider getting blood tests to screen for the mutated RET gene,
Diagnosis and Staging
If you have shown some of the symptoms of thyroid cancer, your medical practitioner will look for small changes in your thyroid and lymph nodes. They may also ask you about your family history.
In the end, the only way to arrive at a definite conclusion is through performing a biopsy. But, before you are scheduled for the surgery, your medical examiner will conduct other tests to rule out the possibility that your symptoms are caused by another condition. Other blood tests will help your medical practitioner learn more about the stage and assess the function of the thyroid.
These blood tests may include:
Thyroid-stimulating hormone (TSH) – this blood test is used to assess the function of the thyroid. It works to measure the level of TSH released by the pituitary gland. This test is used to ascertain the cause of the symptoms related to thyroid cancer. If the levels of TSH are very high, this could be a symptom of hypothyroidism. A very low level of TSH could be indicative of hyperthyroidism. When the condition is cancer, the levels of TSH are usually normal to high.
T3 and Free T4 (thyroid hormones) – the levels of these thyroid hormones will also be measured along with the TSH levels. They will be normal in most cases of cancer.
Calcitonin – this hormone is used by the body to regulate the use of calcium and is formed in the C-cells of the thyroid. The cells that produce this hormone can also turn into medullary thyroid cancer. This test could be used to diagnose the condition as MTC. The presence of MTC is indicated by higher levels of this hormone.
RET oncogene – if you have a family history of MTC or your medical practitioner believes you may have this condition, they may suggest DNA testing to find the mutated RET gene. This test is considered the best way to detect MTC.
Carcinoembryonic antigen (CEA) – levels of this protein are sometimes measured to detect MTC. Those with MTC will typically present higher levels of CEA.
Biopsy – this method of examination involves removing some of the fluids or tissue from the thyroid itself and examining the sample for evidence of cancer. This is done through fine needle aspiration most of the time. A very thin needle will be inserted into the thyroid gland and guided by an ultrasound to its proper position for extracting a sample. Patients will typically leave the hospital the same day after the procedure and only require a small band-aid to cover the tiny puncture. The samples of tissue or fluids will be examined by a pathologist.
Molecular testing of biopsied tissue – as much as 30% of biopsies result in an inconclusive report. This can lead to a portion of or the entire thyroid being removed. To avoid this, especially intrusive surgery, new methods of testing are being introduced. Molecular testing can help to determine if thyroid nodules are malignant or not.
Somatic mutation testing – if the results from examining the biopsied samples are inconclusive, the same tissue can be tested for certain genetic mutations that are associated with cancerous cells. These mutations include BRAF V600E, RET/PTC, PAX8-PPARγ, and RAS. BRAF is especially important in evaluating the likelihood that papillary thyroid cancer will attack again.
miRNA analysis – miRNAs are small pieces of RNA that can impact the way certain genes behave. Some of these miRNAs are connected to cancerous growths. By detecting their presence in a biopsied tissue sample, they can help to determine if a nodule is malignant or not. Because these miRNAs can also be found in the bloodstream, there is an application for this type of testing in blood samples.
