DIAGNOSING THYROID CANCER

Thyroid cancer diagnoses have been increasing in Canada over the past several decades, especially among women aged 40 to 60. However, mortality rates have stayed very low. The Canadian Cancer Society estimated that 130 women and 110 men will die from thyroid cancer in 2020.

Cells in the thyroid can sometimes start to grow or behave abnormally. This may lead to non-cancerous, or benign, conditions such as hypothyroidism, hyperthyroidism, thyroid nodules, thyroiditis, or goitre. Sometimes these changes can cause cancer.

There are four types of thyroid cancer: papillary, follicular, medullary, and anaplastic. Papillary is the most commonly diagnosed, but only a small proportion of these cancers behave aggressively and very few patients die.

Papillary thyroid cancer may form a nodule, but it’s important to note that thyroid nodules are extremely common – over half of people over 60 have one, according to the American Thyroid Association. Women are more likely than men to develop thyroid nodules, but most of them are benign with only 2-12 percent becoming cancerous.

The thyroid gland is a butterfly-shaped endocrine gland located in the lower front of the neck which produces hormones that control your metabolism. Lumps or bumps in this gland are called nodules. What causes them is not known, although iodine deficiency and inflammation of the thyroid can increase the risk of developing thyroid nodules.

WHAT ARE THE SYMPTOMS OF THYROID NODULES?

Changes in the thyroid may be seen or felt, but most thyroid nodules don’t cause symptoms. They are often discovered during a routine physical exam or via medical imaging, like ultrasound, performed for unrelated reasons.

Sometimes the tissue in a nodule makes too much of the thyroid hormones causing hyperthyroidism, which can be seen by performing a thyroid-stimulating hormone (TSH) blood test. However, most thyroid nodules, including those that are cancerous, are actually non-functioning, meaning tests like TSH are normal.

It’s important to see your doctor if you have:

• A persistent cough.
• Difficulty breathing.
• Difficulty swallowing or persistent sore throat.
• Hoarseness or other voice changes.
• Pain in the front of the neck
• Swelling or a lump in the neck.

WHAT DETERMINES IF A THYROID NODULE IS CANCEROUS?

The only way to definitively determine if a thyroid nodule is cancerous is to examine it under a microscope. The most common method is called fine needle aspiration (FNA) biopsy, where a very small needle is inserted into the thyroid nodule and cells are removed for microscopic examination. However, only a small percentage of nodules are cancerous, and, of those, an even smaller percentage requires treatment. Most thyroid cancers are curable and rarely cause life-threatening problems.

At Mayfair Diagnostics, we follow the American College of Radiology’s Thyroid Imaging, Reporting, and Data System (TI-RADS) for the classification and evaluation of thyroid nodules. Our thyroid ultrasound reports to your doctor describe the nodule’s features, assess the risk of malignancy, and help determine next steps, such as the need for FNA or ultrasound follow-up to monitor nodule growth or development of worrisome features.

The goal of TI-RADS is to help you and your doctor balance the benefit of identifying cancers that require treatment against the risk of biopsy and treatment of benign nodules or indolent cancers – cancers that are slow-growing and will almost certainly never be problematic.

WHAT ARE THE RISK FACTORS FOR THYROID CANCER?

Thyroid nodules and other thyroid conditions, such as goitre (enlarged thyroid) and inflammation of the thyroid, can increase the risk of thyroid cancer. Other risk factors include:

• A family history of thyroid cancer.
• A history of significant radiation to the neck.
• A personal history of thyroid cancer.
• Certain hereditary conditions, such as Multiple Endocrine Neoplasia type 2.

HOW DO I GET A THYROID ULTRASOUND?

This exam is covered under your Alberta and Saskatchewan Health Care Insurance Plans and must be requested by a health care practitioner. To determine whether it’s appropriate for you, your doctor will often review your medical and family history, risk factors, how long symptoms have been present, and how they affect daily activities. If a thyroid ultrasound is indicated as a best next course of action, your doctor will provide you with a requisition and the appointment can be booked.

Mayfair has 13 locations in Calgary, one in Cochrane and one in Regina, which offer thyroid ultrasounds. Thyroid biopsies are performed in hospitals or doctors’ offices.

REFERENCES

American Thyroid Association (2018) “Thyroid Nodules.” www.thyroid.org. Accessed June 14, 2021.

Brady, Dr. Bridget (2015) “Thyroid Nodules: Prevalence, Symptoms, Causes, Diagnosis, and Treatments.” www.endocrineweb.com. Accessed June 14, 2021.

Brenner, D. R. et al (2020) “Projected estimates of cancer in Canada in 2020.” Canadian Medical Association Journal. March 02, 2020 192 (9) E199-E205. Accessed June 14, 2021.

Canadian Cancer Society (2021) “Thyroid cancer statistics.” www.cancer.ca. Accessed June 14, 2021.

Canadian Cancer Society (2021) “What is thyroid cancer?” www.cancer.ca. Accessed June 14, 2021.

Topstad, D. and Dickinson, J. A. (2017) “Thyroid cancer incidence in Canada: a national cancer registry analysis.” Canadian Medical Association Journal. Jul-Sep; 5(3): E612–E616. Accessed June 14, 2021.

Vaccarella, S., et al. (2016) “Worldwide Thyroid-Cancer Epidemic? The Increasing Impact of Overdiagnosis.” New England Journal of Medicine, 375;7: 614-17.