How Is Thyroid Cancer Detected?

thyroid cancer test
Thyroid cancer can be detected using a variety of diagnostic and lab tests

Thyroid cancer occurs when abnormal cells have uncontrolled growth in the thyroid gland. In addition to taking your medical history and performing a physical examination, your doctor may use a variety of diagnostic and lab tests to detect the presence of thyroid cancer.

What tests are done to check for thyroid cancer?

Fine needle aspiration (FNA)

One of the best ways to detect thyroid cancer, FNA is a type of biopsy where an extremely thin needle is used to remove (or aspirate) some cells from the thyroid nodule. The aspirated samples are sent to the lab where they are carefully examined for abnormalities. During an FNA, an ultrasound is used to make sure that samples are removed from the right place. Ultrasound-guided FNA biopsies are especially useful in cases where the thyroid nodule is small.

Surgical biopsy

Depending on the results of the FNA, a surgical biopsy may be needed. This type of biopsy is performed under general anesthesia.

Blood tests

Blood tests may be used to measure the levels of T3 and T4 (thyroid hormones), calcitonin and thyroid stimulating hormone (TSH). A blood test is also used to identify mutations of the RET gene, a factor that can cause papillary thyroid cancer and medullary thyroid cancer (MTC).

Thyroid ultrasound

Solid nodules are more likely to be cancerous. An ultrasound can help determine whether a thyroid nodule is solid or filled with fluid.

Computed tomography (CT) scan

A CT scan is an X-ray that takes many pictures of body tissue to create detailed, cross-sectional images. This scan can help identify the size and location of the cancer and show whether it has spread to other parts of the body.

Positron emission tomography (PET) scan

A PET scan can be used to look for cancerous tumor cells and determine whether it has spread beyond the thyroid.

Radioactive iodine uptake scan

This is a nuclear medicine test that involves swallowing a small amount of radioactive iodine (it can also be injected). Once the iodine is given time to be absorbed by the thyroid gland, a special camera is used to identify the location of radioactivity.

Octreotide scan

Patients with suspected medullary thyroid cancer are injected with octreotide and a radioactive substance. Imaging tests are then performed to see how much of the octreotide has been absorbed. This test helps show the location and size of the tumor.

Vocal fold function

Doctors may examine vocal fold innervations because the supplying nerve passes directly through the thyroid gland and can be damaged in the case of steady tumor growth.

What are signs and symptoms of thyroid cancer?

In addition to diagnostic and lab tests, signs and symptoms play an important role in detecting thyroid cancer. Since signs of cancer in the thyroid are not always obvious, it’s important to pay attention to any changes in your body, including:

  • Unusual nodules or bumps on the neck
  • Persistent hoarseness or other voice changes
  • Persistent, unexplained cough
  • Pain in the neck or throat
  • Sensitivity in the neck

If you have had radiation to the neck in the past, you could be at higher risk for the disease and should be particularly aware of the signs listed above.

What are the different types of thyroid cancer?

The four types of thyroid cancer are:

  1. Papillary thyroid cancer: Found in 80% of all thyroid cancer cases.While it tends to grow slowly, this type of thyroid cancer metastasizes to the lymph nodes in the neck. The chances of a favorable outcome for this type of cancer are usually high.
  2. Follicular thyroid cancer: Found in 10-15% of all thyroid cancer cases. It can metastasize to the lymph nodes and is more likely to spread into the blood vessels as well.
  3. Medullary cancer: Found in about 4% of all thyroid cancer cases. It is often detected at an early stage because it produces a hormone called calcitonin. A doctor will look for this hormone in the blood test results.
  4. Anaplastic thyroid cancer: This may be the most severe type of thyroid cancer because it’s aggressive and spreads quickly to other parts of the body. It is both rare and the most difficult to treat.

Papillary thyroid cancer is the most common type and grows slowly in the follicular cells. Follicular thyroid cancer is slightly less common, but it also grows slowly in the follicular cells. Both forms look similar to normal thyroid tissue under a microscope and account for over 90% of thyroid cancers. These two forms are often curable when found in people under 45 years of age. 

Medullary thyroid cancer develops in the C cells and is sometimes the result of genetic syndromes. This cancer does not resemble normal thyroid tissue and accounts for almost 5% of thyroid cancers. This type can be controlled if it is diagnosed before metastasis

The anaplastic form of thyroid cancer is the least common at 2%, but it is fast-growing and harder to treat.


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