Treatment for thyroid cancer depends on the type of thyroid cancer you have, the size of the cancerous nodule or nodules, and the extent to which the cancer has spread, among other factors.
Active surveillance, or watchful waiting
Currently, some experts are recommending that if you have a very small papillary thyroid cancer, you should have active surveillance, also known as "watchful waiting," with regular ultrasounds to monitor changes to your nodule. Research shows that the prognosis is the same for these types of cancer because changes to the nodule that warrant treatment can be detected early enough for treatment.
Percutaneous ethanol injection (PEI)
In some cases, ethanol is injected into a small thyroid cancer, guided by ultrasound to allow for precise placement. This treatment is sometimes recommended for small, slow-growing thyroid cancer as an alternative to surgery, or for a recurrence limited to a small area.
Most thyroid cancer is treated with surgery to remove your thyroid — usually a full thyroidectomy. A full thyroidectomy reduces the chance of recurrence and ensures that other areas of cancer in the gland are not missed.
Less commonly, for a small, non-aggressive papillary cancer, a partial thyroidectomy, known as a lobectomy, may be recommended.
If there is suspicion or evidence that the thyroid cancer has spread to your cervical lymph nodes, they will also be removed during the surgery. This is known as central compartment neck dissection. Up to 50 percent of patients with differentiated papillary, follicular, or Hurthle cell thyroid cancer have involvement of their cervical lymph nodes.
In some cases of small, non-aggressive thyroid cancer, surgery is the only key treatment.
Radioactive iodine (RAI) remnant ablation
After surgery, radioactive iodine (RAI) treatment is often recommended to eliminate any thyroid tissue or affected lymph nodes that remain and to prevent re-growth of any cancerous cells. This is referred to as “remnant ablation.”
RAI therapy is often recommended if your cancer is more advanced, or if there is evidence that it has spread to your lymph nodes or other sites in the body. According to the American Thyroid Association, RAI is recommended when the cancer is aggressive, has spread outside the thyroid gland, or in tumors that are larger than 4 cm (about two inches).
RAI remnant ablation requires that you follow a low-iodine diet and be off any thyroid hormone replacement medication for several weeks in order for it to work best. Your TSH level needs to be above 30 mU/L for optimal absorption of the radioactive iodine
Typically, this period of hypothyroidism is accompanied by symptoms that include fatigue, brain fog, and weight gain. In some cases a different drug called Thyrogen is given, which still allows for effective RAI remnant therapy without hypothyroidism symptoms.
After RAI, there are specific precautions you need to follow, including staying away from others — especially children and pets — for a period of time. (Your doctor will determine how long that time period is.) This is to protect them from radiation exposure. After RAI, you may have some tenderness or swelling in your neck and salivary glands, a dry mouth, dry eyes, or nausea.
Thyroid hormone replacement/suppression therapy
After your thyroidectomy — and RAI if it is recommended — you will be prescribed a thyroid hormone replacement drug such as levothyroxine (Synthroid, Levoxyl, Tirosint) for life, to replace the missing thyroid hormone produced by your gland. Doctors often recommend that you are prescribed a brand name levothyroxine, rather than a generic, to ensure consistency in your dosage.
Depending on the type of cancer, you may be prescribed suppressive doses, designed to keep your TSH very low or undetectable as a way to prevent thyroid cancer recurrence.
For higher-risk patients, experts recommend suppression of TSH to levels below 0.1 mU/L, not to exceed .5 mU/L for five to 10 years. For lower-risk patients, suppression to 0.5 mU/L is recommended, not to exceed 2.0 for five to 10 years. In patients who have evidence of persistent thyroid cancer, suppression to less than 0.1 mU/L is recommended indefinitely.
Less commonly, physicians may prescribe additional liothyronine (synthetic T3 hormone) in addition to the levothyroxine, or a natural desiccated thyroid (NDT) drug like Nature-throid or Armour Thyroid for hypothyroidism symptoms that are not relieved by levothyroxine.
Targeted drug therapy
Research has found that mutations in the BRAF oncogene are common in patients with some forms of thyroid cancer. There are drugs that can target the pathways that allow expression of these genes, known as tyrosine kinase inhibitors, or TKIs.
For advanced thyroid cancers, cancers that do not respond well to RAI, or some cancers that have spread, targeted drug therapy with TKIs are frequently used. These drugs include vandetanib, cabozantinib (Cabometyx), and sorafenib.
External beam radiation
External beam radiation therapy is mainly used for advanced, extensive, or inoperable thyroid cancer. The radiation machine focuses high-energy radiation beams at specific points of your body, targeting cancerous tumors and areas. Treatment usually is performed five days a week for around five weeks, and each treatment takes a few minutes.
Recurrent thyroid cancer
If you have a suspected cancer recurrence after initial treatment, your doctor will likely follow several key steps:
- An ultrasound-guided fine needle aspiration biopsy to confirm the cancer;
- Surgery, if the tumor can be removed;
- Radioactive iodine (RAI) if a radioiodine scan shows that the cancer cells can absorb iodine.
- If the cancerous cells do not absorb iodine, external beam radiation or targeted drug therapy may be used.
Note: Medullary thyroid cancer cells do not absorb iodine, so RAI is not used to treat a recurrence or spread of this type of cancer.
Anaplastic thyroid cancer
Anaplastic thyroid cancer makes up only two percent of all thyroid cancer but is the most dangerous, aggressive, and difficult-to-treat type of thyroid cancer.
If the cancer is contained to the thyroid area, the gland and lymph nodes may be surgically removed. This is not common, however, because anaplastic thyroid cancer has typically spread — or metastasized — to the lymph nodes and other areas of the body by the time it is diagnosed.
Anaplastic cancer cells do not respond to RAI so this treatment is not used.
In some cases, external beam radiation is used, sometimes along with targeted chemotherapy. The goal is to shrink tumors before surgery, control the spread of the cancer, or to target tumors that are too large to be completely treated with surgery.
When anaplastic cancer has affected your breathing, a tracheostomy is usually recommended. This is a surgical hole placed in the neck that allows for easier breathing.
Thyroid cancer in pregnancy
If a woman is pregnant and develops thyroid cancer, or has a recurrence, the treatment process is different. RAI remnant ablation, CT scans, and PET scans are not performed during pregnancy due to the risks that radiation exposure poses to the unborn baby.
If a small, non-aggressive thyroid cancer is detected, doctors often recommend waiting until after your baby is born for further treatment.
If your nodules are affecting your breathing or swallowing, or you have a more advanced or aggressive form of thyroid cancer, a thyroidectomy will be recommended. Thyroid surgery is usually only performed during the second trimester when it poses the least risk to you and your baby.