From surgery to radioactive iodine and beyond: Hope for patients with thyroid cancer
Most patients respond well to standard therapies for thyroid cancer. The five-year survival rate is more than 98 percent, and thyroid cancer is responsible for less than 0.5 percent of all cancer-related deaths. Even in advanced stages, we have many effective weapons in the fight against thyroid cancer.
Thyroid nodules are common and generally are detected during an imaging test performed for some other reason, such as a CT scan after a car accident or during a physical exam of the patient’s neck. Nodules will then be examined by ultrasound and subsequently biopsied depending on their appearance to determine whether the nodule is cancerous, and if so, what type of cancer it is.
Determining a patient’s specific cancer type helps us plan the appropriate treatment. There are four main types of thyroid cancer:
- Papillary thyroid cancer: 80 to 85 percent of cases (a differentiated thyroid cancer)
- Follicular thyroid cancer (including Hurthle cell thyroid cancer): 10 to 15 percent of cases (a differentiated thyroid cancer)
- Medullary thyroid cancer: 1 to 2 percent of cases
- Anaplastic thyroid cancer: less than 2 percent of cases
Every case is different, and we closely work with each patient and their entire care team to determine the most effective treatment options. I’ve outlined our general approach to thyroid cancer as well as more advanced treatment options below.
LISTEN: Dr. Rao discusses treatments for standard and advanced thyroid cancer in the Medical Intel podcast.
Treatment of differentiated thyroid cancers
The type of thyroid surgery is based on the extent of the of thyroid cancer. For smaller, single-nodule thyroid cancers, often a lobectomy (removing only part of the thyroid gland) is sufficient, followed by close monitoring. However, a total thyroidectomy with or without lymph node dissection is recommended for larger, multi-foci thyroid cancers.
Following surgery, we evaluate the full pathology report and determine the specific type of thyroid cancer, the extent of the disease (including sites of local invasion), and its stage. If we confirm a diagnosis of differentiated thyroid cancer (papillary, follicular, or Hurthle cell), then, based on the extent of disease, we could recommend radioiodine therapy.
Radioiodine therapy, also known as RAI therapy, is an important treatment step in differentiated thyroid cancers. Because thyroid cells love iodine, the intent of using a radioactive form of iodine is to “kill” or “ablate” any remaining thyroid cells after surgery.
In preparation for this treatment, a patient needs to refrain from consuming foods with iodine for a few weeks in an effort to “starve” the thyroid cells of iodine, so that they will be “hungry” when the treatment dose is delivered. Additionally, we also want the thyroid stimulating hormone (TSH) to rise, either naturally by withdrawing the thyroid hormone replacement or synthetically using a drug known as Thyrogen®. This will stimulate any remnant or recurrent thyroid cells.
At the time of treatment, we begin with a low-dose of RAI and a diagnostic scan to help us identify the presence of thyroid cells that take up iodine. If the scan proves there is evidence of uptake, we proceed with the higher ablative dose of RAI. One week later, a post-treatment scan is obtained, and we often will use the results of this scan to further stage the cancer. This can show evidence of thyroid cells located outside the thyroid bed, indicating both regional and/or distant spread of the disease that hopefully will be treated with the ablation. The ablative effect on the thyroid cells may take up to six months to notice structural or biochemical changes. RAI after surgery has been shown to reduce tumor recurrence and improve patient outcomes compared with patients who don’t receive postoperative RAI treatment.
Following ablative RAI therapy, the patient must take precautions for one week to protect others from radiation exposure, especially young children and household pets. We provide detailed instructions, which can include:
- Arrange childcare for infants and young children
- Avoid public transportation
- Avoid sharing plates, cups or eating utensils
- Refrain from kissing and physical contact
After surgery and RAI therapy, we want to reduce the risk of recurrence by preventing any remaining thyroid cells from getting larger. Simultaneously, we need to replace the patient’s thyroid hormone following the removal of the thyroid gland. We accomplish both goals through thyroid-stimulating hormone (TSH) suppression therapy.
TSH suppression after thyroid cancer surgery
The dose of thyroid hormone replacement (T4) after surgery is weight based, however the calculated dose for a patient with benign disease is lower than those with thyroid cancer. The higher dose is prescribed to suppress the TSH, which is made in the pituitary, from stimulating any remnant thyroid cells after surgery and RAI therapy. Patients need regular blood tests to make sure their TSH levels are well-controlled.
Concurrently, we also are measuring the protein known as thyroglobulin (which is normally made by the thyroid cells) and the thyroglobulin antibody. In the absence of the gland after surgery and RAI therapy, a patient’s level should be low to undetectable. Hence, we use the thyroglobulin as a tumor marker for differentiated thyroid cancer.
Treatment options for recurrent thyroid cancer
The following options often are necessary to treat recurrent differentiated, medullary, or anaplastic thyroid cancer. We also may need to use these tactics for patients whose papillary or follicular thyroid cancer recurs or doesn’t respond to RAI therapy. Our treatment options in these cases include:
- Surgery: We may be able to resect medullary or anaplastic thyroid tumors or recurrent cancers that are localized in the neck, and this treatment offers the best survival.
- Alcohol ablation: This percutaneous treatment can be used to treat localized differentiated thyroid cancer that has failed the standard therapies by focally ablating the patient’s nodule with an ethanol injection.
- Radiation therapy: If the patient’s thyroid cancer metastasizes to bones, such as the spine or ribs, it can be difficult to resect the lesions surgically. Radiation therapy, though less commonly used, can target these sites.
- Targeted therapies: For cases in which the patient’s thyroid cancer recurs after RAI ablation and are considered RAI-refractory disease (which means their disease no longer responds to RAI therapy) and for disease not surgically resectable, we may turn to tyrosine kinase inhibitors, such as lenvatinib (Lenvima®) or sorafenib (Nexavar®) where these agents have been approved for use in differentiated thyroid cancer. Additionally, vandetanib (Caprelsa®) and cabozantinib (Cometriq®) have been approved for use in advanced medullary thyroid cancers. These oral chemotherapy medications provide systemic therapy for patients with rapidly progressive or metastatic disease. Patients with resectable or non-resectable cancer or anaplastic thyroid cancer should also be considered for clinical trials.
In cases of asymptomatic but persistent thyroid cancer, active surveillance is very important. Close monitoring can give the patient peace of mind and allow the doctor to quickly act if the cancer begins to grow or spread. However the decision to operate or initiate a more aggressive medication, such as those listed above, depends on several factors, including the patient’s symptoms, location of disease, and how fast the disease is growing. In many cases, especially if the patient is asymptomatic and their known sites of disease are remaining stable, it may be preferable to spare the patient the financial cost and stress of treatment for what may be little or no noticeable benefit.
There are many effective methods available to treat patients with advanced thyroid cancer. Through a team-based decision-making process that includes the patient, their endocrinologist, surgeon, nuclear medicine specialist and potentially other providers, we can create a plan that addresses each patient’s unique concerns and provides the best chance for a successful outcome.