Most of us rarely think about our thyroid, but this butterfly-shaped gland – located at the front of the neck between the larynx (voice box) and trachea (wind pipe) – plays many important roles in the human body.
The thyroid is part of the endocrine system. Thyroid hormones help regulate functions like metabolism, weight, heart rate, blood pressure and body temperature, and they also help the brain, heart, lungs and muscles function.
Thyroid disorders and diseases, such as hyperthyroidism (too much thyroid hormone), hypothyroidism (too little thyroid hormone) or the growth of nodules (lumps) can affect people of any age. Thyroid cancer can also strike at any age, but it most often develops in people 15 to 49 years old, and it’s the most commonly diagnosed cancer in people 15 to 29. Almost 80% of people diagnosed with thyroid cancer are women, and incidence rates in women have been increasing since the mid-1980s.
According to the Public Health Agency of Canada, thyroid cancer rates are rising faster than those of all other cancers (likely due, in part, to improved diagnostic techniques). It is the tenth most common cancer in Canada, and an estimated 6,300 people were predicted to receive a thyroid cancer diagnosis in 2015.
Are you at risk?
Risk factors for thyroid cancer include:
- family history of the disease
- exposure to ionizing radiation (e.g., X-rays)
- age over 40
- non-cancerous thyroid conditions
- certain hereditary conditions
- tall height
In most thyroid cancer patients, however, the cause of the disease is unknown.
To reduce your risk, the Canadian Cancer Society recommends maintaining a healthy weight, eating fruit and vegetables, and avoiding unnecessary exposure to radiation. If you think you may be at higher risk (for example, because your family has a history of thyroid cancer), talk to your physician about testing.
Signs and symptoms
The first sign of thyroid cancer is often a nodule at the front of the neck. Nodules are quite common – in most cases, they are benign (non-cancerous), but about 5% of the time, they are malignant (cancerous). A swollen lymph node or gland in the neck may also be a sign of cancer.
Other symptoms may include a hoarse throat, a feeling of fullness in the neck, difficulty swallowing or breathing, a persistent sore throat or cough, or neck pain.
If you experience any of these symptoms, see your physician – early detection increases the success of treatment.
Diagnosing thyroid cancer
Your physician may use a combination of tests to check for thyroid cancer, including a physical exam, blood tests, a biopsy of a thyroid nodule, laryngoscopy or imaging tests (ultrasound, MRI, CT scan, PET scan, chest X-ray). There is also a test called the radioactive iodine scan, also known as a radionuclide scan or radioisotope scan, that uses a small amount of radioactive material to detect nodules.
For individuals who have thyroid cancer, many of these tests also help determine the tumour’s grade (how different the cells are from normal cells, the tumour’s growth rate, and the likelihood of the cancer spreading) and its stage (a classification based on its location, size and how much it has spread). Grading and staging help physicians choose a course of treatment.
Treating thyroid cancer
Thyroid cancer has four main types: papillary, follicular, medullary and anaplastic. Papillary is the most common (80%–85% of cases), and follicular is the next most common (7%–15% of cases). These two types are “differentiated” forms of thyroid cancer, meaning that the cancer cells share some characteristics with normal cells (such as using iodine to function).
Treatment depends on the type of thyroid cancer, the cancer’s grade and stage, and the age and general health of the patient. A treatment plan may include surgery to partially or completely remove the thyroid, radiation therapy, hormone therapy, chemotherapy and, for some cases of medullary thyroid cancer, biological therapy.
The prognosis (health outcome) depends on several factors, such as a patient’s age, tumour size and whether the disease has spread beyond the thyroid. Survival rates for these cancers are very high: in Canada, the five-year survival is 98%. Medullary and anaplastic thyroid cancer are much rarer and tend to have a poorer prognosis. Again, chances of recovery will depend on factors such as tumour size and whether the cancer has metastasized (spread).
Life after thyroid cancer
Thyroid cancer can exact a heavy physical, mental and emotional toll that may linger even after treatment has ended.
After the thyroid is removed, patients must take thyroid hormone replacement pills. Without this therapy, cancer survivors are at risk of hypothyroidism (symptoms include fatigue, sleeping difficulties, weight gain, cognitive problems, anxiety, depression, joint pain and others). Physicians adjust the level of hormone based on blood tests.
Survivors must remain vigilant about regular medical check-ups and cancer screening, as the disease can return. A wellness plan, developed with help from healthcare professionals, can help people regain their strength, cope with side effects and stress, and reduce the risk of cancer recurrence.
For information and support, many people find it helpful to meet with others who have had a similar experience. To find peer support and family support groups, contact the Canadian Cancer Society office in your area or join the organization’s online community, CancerConnection.ca. Professional counselling can also help people cope with cancer, its treatment and its after-effects.