Thyroid Cancer

Thyroid cancer starts in your thyroid, the small, butterfly-shaped gland at the base of your neck. As part of the endocrine system, the thyroid makes hormones that keep many of your body's basic functions running smoothly.

Thyroid cancer is relatively uncommon compared to other forms of cancer. The most common types are highly treatable and often curable. Early detection, good nutrition and attention to your overall health can make a difference in your treatment and recovery.

Learn more about the causes, symptoms, and treatments for thyroid cancer, as well as how to support your nutrition and health during treatment and recovery.

Thyroid cancer starts when abnormal cells in your thyroid gland begin growing and spreading uncontrollably. The thyroid sits in the front of your neck, below your Adam’s apple and just above your windpipe. 

The thyroid makes hormones that help regulate many important body functions, including metabolism, energy use, heart rate, body temperature, digestion, and the normal functioning of many organs and tissues throughout the body.

There are several types of thyroid cancer. Each grows and behaves differently, which can affect treatment (1):

• Papillary is the most common type, accounting for 70-80% of thyroid cancer cases. It can develop at any age and tends to grow slowly.
• Follicular accounts for 10-15% of cases and tends to affect people over 50.
• Medullary is a rare form and accounts for only about 2% of thyroid cancer cases. It may run in families.
• Anaplastic is even rarer and found in less than 2% of people with thyroid cancer. It is an aggressive type of thyroid cancer and harder to treat.

Doctors don’t know exactly what causes thyroid cancer, but these factors may increase the risk (2,3):

• Being female — Women are three times as likely as men to develop thyroid cancer.
• Age — You can get thyroid cancer at any age, but it’s most commonly diagnosed in people aged 30 through 60s, with papillary more common in younger adults and follicular/anaplastic more common in older people.
• Being overweight
• Family history
• Low iodine intake
• Radiation therapy for head and neck cancer, especially during childhood or exposure to radiation fallout
• Certain inherited syndromes are linked to medullary thyroid cancer. These include multiple endocrine neoplasia type 2A or 2B, Cowden syndrome, or familial adenomatous polyposis.

Many people develop thyroid cancer without any identifiable cause.

The most common sign of thyroid cancer is a lump or nodule in the lower part of your neck that you can see or feel. If the nodule is large or cancer has spread, you might experience (1,2,3):

• Pain in your neck, jaw, or ear
• A tickle in your throat
• Pain or difficulty swallowing
• Voice hoarseness
• Swollen lymph nodes
• Fatigue
• Unintentional weight loss

Early-stage thyroid cancer usually doesn’t cause symptoms or show up on routine thyroid blood work, so it’s important for your doctor to check your neck for any lumps or swelling during regular exams.

Most thyroid nodules are benign (not cancerous). Less than one in ten cases will be thyroid cancer, but any nodule should be checked (1). It’s much easier to treat thyroid cancer when it’s detected early.

If your doctor feels a thyroid nodule, they may order blood tests, an ultrasound or other imaging tests. If anything looks suspicious, they’ll do a fine needle biopsy to remove cells and check them for cancer.  

If you are diagnosed with thyroid cancer, doctors will determine what type of thyroid cancer it is and then stage it to help guide your treatment and predict your outlook. 

Staging describes how large the tumour is and whether it has spread (2):  

• Stage I - A very small tumour (2 cm or less) contained within the thyroid
• Stage II - A larger tumour (2-4 cm) still within the thyroid that may or may not have spread to nearby lymph nodes
• Stage III - A larger tumour (over 4 cm) that remains completely in the thyroid, or a tumour of any size that has grown outside the thyroid to the muscles around the thyroid gland. The cancer may or may not have spread to nearby lymph nodes, but not to other parts of the body
• Stage IV - Advanced cancer that has spread to nearby lymph nodes or other parts of the body

All anaplastic thyroid cancers are considered stage IV, regardless of their size, because they grow and spread quickly.

Surgery to remove part or all of your thyroid is the most common treatment for thyroid cancer. If cancer has spread to lymph nodes, your surgeon will remove these too. Depending on your type and stage of cancer, your treatment plan may also include:

• Radioactive iodine (radioiodine) therapy is a pill that contains radioactive iodine. Thyroid tissue absorbs the radioactive iodine, which kills cancerous tissue. Before treatment, you’ll follow a low-iodine diet for one to two weeks, which means avoiding foods like dairy products, eggs, seafood, and soy, as well as iodised salt. With this therapy, thyroid-stimulating hormone (TSH) needs to be stimulated through withdrawal or by recombinant TSH injection for effective radioiodine uptake. Not all thyroid cancers will benefit from radioiodine.
• Radiotherapy uses energy beams to kill or shrink tumours. It’s typically used if your cancer can’t absorb radioactive iodine from a pill.
• Thyroid hormone therapy stops new thyroid tissue from growing and cancer from returning. This may be lifelong, especially if the entire thyroid has been removed.
• Chemotherapy uses strong medicines to kill cancer cells and shrink tumours. It’s mainly used for advanced thyroid cancers.
• Targeted therapy blocks specific proteins that cancer cells need to grow. It’s also mainly used for advanced cancers.

Papillary and follicular thyroid cancer, diagnosed and treated in early stages, both have an excellent prognosis or outlook. Other types of thyroid cancer may be harder to treat and can have a higher chance of returning.

However, each person’s cancer and treatment course are different, so it’s hard to predict what may happen. Your doctor can tell you more about what you might expect during recovery and your long-term outlook.

Treatments for thyroid cancer can cause side effects like loss of appetite, nausea, or problems swallowing. It may take several weeks or months to recover from your treatment, but side effects are usually temporary. If your treatment includes removing your entire thyroid, you’ll likely need to take thyroid hormone replacement medicine for life.

Early diagnosis and treatment typically lead to better outcomes. After treatment, some early-stage thyroid cancers can be cured. The cancer may also go into remission, which means that signs and symptoms are gone and the cancer is under control but not cured. 

Sometimes, cancer returns after treatment, so it’s critical to follow your doctor’s follow-up and monitoring plan.

Unlike some other cancers affecting the head, neck, or digestive system, many people with thyroid cancer are able to continue eating normally throughout much of their treatment. However, nutrition support may still be helpful after surgery or when preparing for radioactive iodine treatment.

An oncology dietitian can create a personalised nutrition plan to help you meet your calorie, protein, and other nutritional needs and troubleshoot swallowing problems, loss of appetite, or early fullness. They may recommend:

• Soft, moist foods, easy-to-swallow foods
• Smaller, more frequent meals and snacks if you get full quickly
• Oral nutrition supplements like shakes, powders, or puddings that provide extra protein and calories in a small volume

Your medical team will support you throughout every step, from diagnosis through recovery. Stay in close contact, ask questions, and alert them to any problems or challenges you may encounter.