Treatment Update: Thyroid Cancer
Each year in the United States, approximately 44,000 people are diagnosed with thyroid cancer. It is diagnosed at a younger age than most cancers, and is much more likely to develop in women than in men.
The thyroid is a butterfly-shaped gland that sits along the front of the windpipe. It absorbs a mineral called iodine from the bloodstream to produce hormones that help regulate metabolism and keep the brain, heart and other organs working as they should. Thyroid cancer starts when healthy cells in the thyroid grow out of control, causing a tumor to develop.
Thyroid cancer doesn’t always have symptoms, especially early in the disease. Symptoms, when they occur, can include:
- A lump on the neck which can be felt through the skin
- Changes to the voice, including hoarseness
- Difficulty swallowing
- Pain in the neck and throat
- Swollen lymph nodes in the neck
Diagnosis of thyroid cancer is usually made through a combination of physical exam, blood tests, imaging tests and biopsy. In a biopsy, a sample of thyroid tissue is removed using a long, thin needle and examined in a laboratory to look for cancer cells.
The American Joint Committee on Cancer has created a system that’s used to describe the stages of thyroid cancer. Called the “TNM” system, it focuses on three things:
- T (tumor): How big is the main tumor, and has it spread to other areas of the body?
- N (nodes): Has the cancer spread to nearby lymph nodes? (Lymph nodes are bean-shaped cells that help fight infection.)
- M (metastasized): Has the cancer metastasized (spread) to other areas of the body or organs, such as the lungs, liver or bones?
Papillary thyroid cancer is the most common type of thyroid cancer, accounting for approximately 85 percent of cases. It arises from follicular cells, which produce and store thyroid hormones. Papillary and follicular thyroid cancer are sometimes referred to together as differentiated thyroid cancer. Other types, which are much more rare, are anaplastic thyroid cancer and medullary thyroid cancer.
Treatment approaches for thyroid cancer depend on the type and stage of the cancer and the individual’s overall health. Tumors that are very small and have a low risk of metastasizing might not need immediate treatment. Instead, doctors may suggest “active surveillance” in which the cancer is frequently monitored through blood tests and ultrasound imaging tests.
Most treatment approaches include surgery to remove all or part of the thyroid. The type of surgery depends on the cancer’s type, size and whether it has spread beyond the thyroid.
Surgical options include:
Thyroidectomy, the removal of the entire thyroid (total thyroidectomy) or most of the thyroid (near-total thyroidectomy).
Thyroid lobectomy, in which a portion of the thyroid is removed. This option may be used when there is a slow-growing tumor in only one part of the thyroid.
Lymph node dissection, in which lymph nodes in the neck are removed at the time of thyroidectomy or lobectomy. The lymph nodes can then be examined for signs of cancer.
Radiation therapy is often given after surgery to destroy any remaining cancer cells.
Intraoperative radiation therapy (IORT) directs radiation to the tumor while sparing the healthy surrounding tissue. Another type of radiation therapy, called internal radiation therapy, uses a radioactive substance sealed in needles, seeds, wires or catheters placed directly into or near the tumor.
The administration of radioactive iodine (RAI) after surgery is standard practice in cases of papillary or follicular thyroid cancer (differentiated thyroid cancer) that has spread to the neck or other parts of the body. Given in capsule form, RAI ablates (destroys) any thyroid cancer cells not removed in surgery without harming healthy tissue.
Thyroid hormone therapy
The medication levothyroxine (Synthroid, Levoxyl) is taken for life after surgery. It supplies the levels of hormone the thyroid would normally produce. Levothyroxine also suppresses the production of thyroid-stimulating hormone (TSH). High TSH levels can stimulate the growth of any remaining cancer cells.
Targeted therapies focus on specific molecules and cell mechanisms thought to be important for cancer cell survival and growth, taking advantage of what researchers have learned in recent years about how tumors grow.
Targeted therapy in the treatment of papillary or follicular thyroid cancer (differentiated thyroid cancer)
Most cases of differentiated thyroid cancer (DTC) can be successfully treated by surgery and radioactive iodine therapy. Targeted therapy may be used if those approaches aren’t effective.
Multikinase inhibitors. Lenvatinib (Lenvima) and sorafenib (Nexavar) inhibit (block) tumors from forming new blood vessels, which tumors need to grow. These drugs also inhibit the production of proteins that help cancer cells grow.
RET inhibitor. Some differentiated thyroid cancers exhibit changes in the RET gene that cause the production of an abnormal form of the RET kinase protein, leading to the growth of cancer cells. Selpercatinib (Retevmo) targets (attacks) the abnormal RET protein.
NTRK inhibitors. Changes in one of the NTRK genes can help cancer cells grow. Larotrectinib (Vitrakvi) and entrectinib (Rozlytrek) target and disable the abnormal proteins made by NTRK genes.
Tyrosine kinase inhibitor. Cabozantinib (Cometriq, Cabometyx) works by blocking the action of an abnormal protein that signals cancer cells to multiply. It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of DTC that has progressed after treatment with a multikinase inhibitor.
Targeted therapy in the treatment of medullary thyroid cancer
Targeted therapy is of particular value in the treatment of medullary thyroid cancer, because thyroid hormone-based treatments (including radioactive iodine therapy) are not effective against this type of cancer.
Multikinase inhibitors. Vandetanib (Caprelsa) and cabozantinib (Cometriq) stop cancer cells from growing by inhibiting proteins and stopping the growth of new blood vessels (which tumors need to grow).
RET inhibitors. As with differentiated thyroid cancer, some medullary thyroid cancers exhibit changes in the RET gene that cause the production of an abnormal form of the RET kinase protein. Selpercatinib (Retevmo) and pralsetinib (Gavreto) attack the abnormal RET protein.
Targeted therapy in the treatment of anaplastic thyroid cancer
Because most other therapies are not very effective against anaplastic thyroid cancer, targeted therapies are of significant interest in the treatment of this type of cancer.
BRAF and MEK inhibitors. Some anaplastic thyroid cancers exhibit changes in the BRAF gene, causing the creation of proteins that help cancer cells grow. Dabrafenib (Tafinlar) inhibits the BRAF protein and trametinib (Mekinist) inhibits a related protein called MEK.
RET inhibitors. As in differentiated thyroid cancer and medullary thyroid cancer, some anaplastic thyroid cancers exhibit changes in the RET gene that cause the production of an abnormal form of the RET kinase protein. Selpercatinib (Retevmo) attacks the abnormal RET protein.
NTRK inhibitors. A small number of anaplastic thyroid cancers exhibit changes in one of the NTRK genes that can help cancer cells grow. As in differentiated thyroid cancer, larotrectinib (Vitrakvi) and entrectinib (Rozlytrek) target and disable the abnormal proteins made by NTRK genes.
Chemotherapy, the use of drugs to destroy cancer cells by stopping the ability of the cells to grow and divide, isn’t commonly used in the treatment of thyroid cancer. It is sometimes recommended for people with anaplastic thyroid cancer, often in combination with radiation therapy.
All cancer treatments can cause side effects. It’s important that you report any side effects that you experience to your health care team so they can help you manage them. Report them right away—don’t wait for your next appointment. Doing so will improve your quality of life and allow you to stick with your treatment plan. It’s important to remember that not all people experience all side effects, and people may experience side effects not listed here.
Side Effects of Radiation Therapy
Fatigue is the most common side effect of intraoperative radiation therapy (IORT). Additionally, changes to the skin can frequently occur. The changes can include dryness, swelling, peeling, redness and (rarely) blistering. If a reaction occurs, contact your health care team so the appropriate treatment can be prescribed. It’s especially important to contact your health care team if there is any open skin or painful area, as this could indicate an infection. Infections can be treated with an oral antibiotic or topical antibiotic cream.
Radioactive iodine (RAI) may cause temporary side effects, including neck tenderness and swelling, swollen salivary glands, loss of taste or changes in taste, dry eyes and dry mouth.
Side Effects of Targeted Therapy
Targeted therapy doesn’t have the same effect on the body as do chemotherapy drugs, but it can still cause side effects. Side effects of targeted therapies can include diarrhea, liver problems (such as hepatitis and elevated liver enzymes), nerve damage, high blood pressure and problems with blood clotting and wound healing.
Side Effects of Chemotherapy
The side effects of chemotherapy depend on the type and dose of drugs given and the length of time they are used, and can include:
- Hair loss
- Increased risk of infection (from having too few white blood cells)
- Easy bruising or bleeding
- Changes in memory or thinking
- Peripheral neuropathy (numbness or tingling in hands and feet)
There are certain side effects that may occur across different treatment approaches. Following are tips for managing these side effects. Your health care team may have additional guidance for your specific treatment type.
Managing Digestive Tract Symptoms Nausea and Vomiting
- Eat small, frequent meals.
- Avoid food with strong odors, as well as overly sweet, greasy, fried or highly seasoned food.
- Eat meals cold or at room temperature, which often makes food more easily tolerated.
- Having something in your stomach when you take medication may help ease nausea.
- Drink plenty of water. Ask your doctor about using drinks such as Gatorade, which provide electrolytes. Electrolytes are body salts that must stay in balance for cells to work properly.
- Over-the-counter medicines such as loperamide (Imodium A-D and others) and prescription drugs are available for diarrhea but should be used only if necessary and with your health care team’s knowledge and approval. If the diarrhea is bad enough that you need medicine, contact a member of your health care team.
- Choose foods that contain soluble fiber, like beans, oat cereals and flaxseed, and high-pectin foods such as peaches, apples, oranges, bananas and apricots.
- Avoid food high in refined sugar and those sweetened with sugar alcohols such as sorbitol and mannitol.
Loss of appetite
Eating small meals throughout the day is an easy way to take in more protein and calories, which will help maintain your weight. Try to include protein in every meal. Nutrition shakes or protein drinks are a way to add calories to your daily diet.
To keep from feeling full early, avoid liquids with meals or take only small sips (unless you need liquids to help swallow). Drink most of your liquids between meals.
Keep high-calorie, high-protein snacks on hand such as hard-boiled eggs, peanut butter, cheese, ice cream, granola bars, liquid nutritional supplements, puddings, nuts, canned tuna and trail mix.
If you are struggling to maintain your appetite, talk to your health care team about whether appetite-building medication could be right for you.
There are a number of options for pain relief, including prescription and over-the-counter medications. It’s important to talk to a member of your health care team before taking any over-the-counter medication to determine if it is safe and will not interfere with your treatment. Many pain medications can lead to constipation. Your doctor can recommend over-the-counter or prescription medications that help to avoid or manage constipation.
Physical therapy, acupuncture and massage may also be of help in managing your pain. Consult with a member of your health care team before beginning any of these activities.
Fatigue (extreme tiredness not helped by sleep) is one of the most common side effects of many cancer treatments. If you are very fatigued while on treatment, your doctor may lower the dose of the drug(s), as long as it does not make the treatment less effective. If you are experiencing fatigue, talk to your doctor about whether taking a smaller dose is right for you.
There are a number of other tips for reducing fatigue:
Take several short naps or breaks during the day.
Take walks or do some light exercise, if possible.
Try easier or shorter versions of the activities you enjoy.
Ask your family or friends to help you with tasks you find difficult or tiring.
There are also prescription medications that may help, such as modafinil. Your health care team can provide guidance on whether medication is the right approach for your individual circumstances.
Q: Are there risk factors for developing thyroid cancer?
A: Although it’s not clear what causes thyroid cancer, there are factors that increase the risk of it developing:
Gender. Thyroid cancer occurs approximately three times more frequently in women than in men.
Exposure to radiation. Previous radiation therapy treatments to the head and neck increase the risk of thyroid cancer.
Genetic syndromes. Inherited genetic syndromes that increase the risk of thyroid cancer include familial medullary thyroid cancer, multiple endocrine neoplasia, Cowden’s syndrome and familial adenomatous polyposis.
Based on your family history, genetic testing may be recommended to look for genes that increase your risk of developing thyroid cancer.
Q: Is immunotherapy used as a treatment approach for thyroid cancer?
A: Our immune system is constantly working to keep us healthy. It recognizes and fights against danger, such as infections, viruses and growing cancer cells. In general terms, immunotherapy uses our own immune system as a treatment against cancer. Immunotherapy is currently being studied in clinical trials as a treatment approach for thyroid cancer.
Q: What is a treatment summary and why is it important?
A: Keeping your own records up-to-date in the form of a treatment summary can be helpful, as it allows you and your family members to have instant access to the specifics of your thyroid cancer diagnosis and treatment. A treatment summary should include:
- Your name and date of birth
- Date of diagnosis
- Prescribed therapy/therapies, including dates started and stopped and dosages when appropriate
- Dates and types of baseline and post-diagnosis testing and the results of these tests
- Other medications and supplements you are taking
- Names, affiliations and contact information of all members of your health care team
Ask the members of your health care team what they suggest be included. Take your personal record with you when you visit any doctor, not just your oncologist.